SYSTEMS AND METHODS FOR AIR TEMPERATURE CONTROL INCLUDING R-32 SENSORS

Abstract

The present invention provides a system for detecting a quantity of R-32 refrigerant in an air temperature controller using R-32 refrigerant, and a method for installing an R-32 sensor configuration in the air temperature controller using R-32 refrigerant. The system includes an R-32 control board, a first R-32 sensor, and a second R-32 sensor. The first R-32 sensor and the second R-32 sensor are connected in series and electrically coupled to the R-32 control board. Each of the first R-32 sensor and the second R-32 sensor includes sensing components configured to detect the quantity of R-32 refrigerant.

Description

SYSTEMS AND METHODS FOR CONTROLLING AIR TEMPERATURE THAT INCLUDES R-32 SENSORS ALA / a / zu^o / uuoouu CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. application No. 17 / 164,618, filed on February 1, 2021, which is incorporated herein in its entirety by reference for all purposes. TECHNICAL FIELD The present invention relates to heating, ventilation and air conditioning (HVAC) systems, and more particularly to HVAC systems that use a refrigerant classified as “A2L” according to Standard 34 of the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) designated R-32. BACKGROUND OF THE INVENTION Modern residential and industrial buildings use HVAC systems to maintain controlled indoor climates. Generally, HVAC systems circulate air over low- or high-temperature sources and distribute the cooled or heated air throughout the building to adjust the indoor ambient air temperature. Modern HVAC systems utilize the well-known physical principle that a fluid changing from a gas to a liquid releases heat, while a fluid changing from a liquid to a gas absorbs heat, to efficiently cool or heat the air before distribution. Typical HVAC systems circulate a refrigerant fluid through a closed-loop network of pipes, using compressors and other devices to manipulate the refrigerant and cause it to change between its liquid and gaseous phases.In general, these phase transitions occur within the evaporator and condenser coils of the HVAC, which are part of the closed loop and are designed to transfer heat between the circulating refrigerant and the flowing ambient air. For a long time, HVAC systems used, and in some places still use, a chemical called R-12 or a chemical called R-22 as a refrigerant. While R-12 and R-22 are classified as A1 refrigerants under ASHRAE Standard 34, meaning they are non-flammable and have lower toxicity, both pose a significant threat to the ozone layer and the environment. Although R-22 is an improvement over R-12 because it has a much lower ozone depletion potential (ODP) (0.05 for R-22 compared to 1.0 for R-12) and global warming potential (GWP) (1,760 for R-22 compared to 10,200 for R-12), it still has adverse effects on the ozone layer and the environment. Therefore, in an attempt to solve the problem of ozone layer depletion, the industry, with the help of regulations, began the transition to the use of R410A, which is another A1 refrigerant but with an ODP of 0.However, R-410A has a GWP (2,088) that is even higher than that of R-22. Therefore, in an attempt to address the global warming problem caused by the use of older refrigerants, the industry has begun transitioning from A1 refrigerants to those classified as A2L refrigerants. This means that these refrigerants are still low in toxicity but, instead of being non-flammable, have very low flammability. Typically, these A2L refrigerants have a much lower GWP than the A1 refrigerants currently and previously in use, while still having an ODP of 0, like R-410A. Some examples of viable A2L refrigerants include, but are not limited to, R-32 and R-454b, which have an ODP of 0 and GWPs of 675 and 466, respectively. However, this now means that HVAC systems incorporating these A2L refrigerants must employ safety measures to ensure that the refrigerants do not ignite in the event of an A2L refrigerant leak.Some of the safety requirements for systems using A2L refrigerants include turning on a blower in the HVAC system while shutting down all other HVAC components within the required timeframe after detecting an A2L refrigerant leak, as mandated by A2L safety standards. Current HVAC systems not only fail to meet these requirements within the required timeframe, but they also fail to detect A2L leaks. BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a system for detecting a quantity of R-32 refrigerant in an air temperature controller using R-32 refrigerant, and a method for installing an R-32 sensor configuration in the air temperature controller using R-32 refrigerant. The system includes an R-32 control board, a first R-32 sensor, and a second R-32 sensor. The first R-32 sensor and the second R-32 sensor are connected in series and electrically coupled to the R-32 control board. Furthermore, each of the first R-32 sensor and the second R-32 sensor includes sensing components configured to detect the quantity of R-32 refrigerant. In one or more of the embodiments described herein, each of the first R-32 sensor and the second R-32 sensor includes a sensor relay electrically arranged between a bus connector input and a bus connector output.Furthermore, in one or more of the modes described herein, each of the first R-32 sensor and the second R-32 sensor performs an internal self-diagnostic test, and if the sensor passes the internal self-diagnostic test, the sensor closes the sensor relay allowing power to pass through the sensor. The method for installing the R-32 sensor configuration in an air temperature controller using R-32 refrigerant involves removing the R-32 control board, the first R-32 sensor, and the second R-32 sensor from the air temperature controller. The first R-32 sensor is electrically coupled to the R-32 control board, and the second R-32 sensor is also coupled to the R-32 control board. Furthermore, the first and second R-32 sensors are connected in series to the R-32 control board. In one or more of the modes described herein, each of the first and second R-32 sensors performs an internal self-diagnostic test. If the sensor passes the internal self-diagnostic test, it closes its sensor relay, allowing power to flow through it. The HVAC systems described herein provide components and architecture that enable the detection of R-32 refrigerant leaks and ensure compliance with safety requirements within the required timeframe. Furthermore, within these HVAC systems, the components and architecture for detecting the quantity of R-32 refrigerant, as described herein, ensure system compliance by guaranteeing that all R-32 sensors function correctly while the HVAC system is operating. Therefore, a system for detecting the quantity of R-32 refrigerant can be installed to allow HVAC systems using R-32 refrigerant to operate safely while reducing the negative environmental impact of current HVAC systems.The foregoing and other objects, features and advantages of the invention will be evident from the following more particular description of the invention, as illustrated in the accompanying drawings, where the same reference numbers represent similar parts of the invention. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the present modalities and their advantages can be obtained by consulting the following description together with the accompanying drawings, in which the same reference numbers indicate similar characteristics, and where: Figure 1 shows a non-communicating HVAC system using an A2L refrigerant, according to one or more modes; Figure 2 is a flowchart illustrating one modality of a method for operating a non-communicating HVAC system using an A2L refrigerant, according to one or more modalities; Figure 3 shows a communicating HVAC system that uses an A2L refrigerant, according to one or more modes; Figure 4 is a flowchart illustrating one modality of a method for operating a communicating HVAC system using an A2L refrigerant, according to one or more modalities; Figure 5 shows another non-communicating HVAC system using an A2L refrigerant, according to a second modality; Figure 6 is a flowchart illustrating another modality of a method for operating a non-communicating HVAC system using an A2L refrigerant, according to one or more modalities; Figure 7 shows another HVAC system with communication that uses an A2L refrigerant, according to one or more modes; Figure 8 is a flowchart that illustrates another modality of a method for operating a non-communicating HVAC system using an A2L refrigerant, according to one or more modalities; Figure 9 is an illustrative configuration of A2L sensors for use in an HVAC system using an A2L refrigerant, according to one or more modalities; and Figure 10 is a flow diagram illustrating one modality of a method for installing and testing an A2L sensor configuration for use in an illustrative configuration of A2L sensors for use in an HVAC system using an A2L refrigerant, according to one or more modalities. DETAILED DESCRIPTION OF THE INVENTION This description generally refers to HVAC systems, both with and without communication, designed to incorporate the use of an A2L refrigerant and comply with the safety standards imposed on systems using A2L refrigerants. While any ASHRAE Standard 34 A2L refrigerant may be used, in one or more configurations, the A2L refrigerant may be R-32. R-32, also known as difluoromethane, is an organic compound with the chemical formula CH₂GF₅. As discussed previously, R-32 has a GWP of 675 and an ODP of 0. In one or more configurations, all references to A2L below may specifically refer to R-32.By way of example, throughout the descriptive memory, an A2L refrigerant may be an R-32 refrigerant, an A2L sensor may be an R-32 sensor that is configured to detect quantities of R-32 refrigerant in order to detect an R-32 refrigerant leak, and an A2L control board may be a control board configured to work with R-32 sensors to implement safety measures if an R-32 refrigerant leak is detected. Figure 1 shows a non-communicating HVAC system using an A2L refrigerant, according to one or more modes. In one or more configurations, an HVAC system 100 can be used to distribute cooled or heated air throughout a building 110 to adjust the ambient air temperature within 111 the building 110. The HVAC system may include an indoor unit 120, an outdoor unit 130, a thermostat 140, an A2L control board 150, and an A2L sensor 170. Generally, in one or more configurations, the indoor unit 120 can be fluidly coupled to the outdoor unit 130 so that an A2L refrigerant can flow between the indoor unit 120 and the outdoor unit 130 to cool or heat the air inside the indoor unit 120. In addition, in one or more configurations, both the indoor unit 120 and the outdoor unit 130 can be electrically coupled to the thermostat 140.The thermostat 140 can be configured to use on / off type signals for communication and control of the indoor unit 120 and the outdoor unit 130. Additionally, in one or more modes, the A2L 150 control board can be electrically coupled directly to the indoor unit 120 and the A2L 170 sensor. The A2L 150 control board can act as a power pass-through for parts of the indoor unit 120, the outdoor unit 130, and the thermostat 140, and can be configured to block power supply to certain parts of the indoor unit 120, the outdoor unit 130, and the thermostat 140 if there is an A2L refrigerant leak in the system. Additionally, an A2L 170 sensor can be physically placed inside the indoor unit 120 and electrically coupled to the A2L 150 control board. The A2L 170 sensor can be configured to send signals to the A2L 150 control board when an A2L refrigerant leak is detected. In one or more configurations, the indoor unit 120 can be located inside building 110, unit 111. The indoor unit 120 can be configured to distribute either cooled or heated air to the rooms inside building 110, unit 111. The indoor unit 120 can be any type of HVAC system that includes a blower 121 and a heat exchanger 127 having an indoor evaporator coil 124. Therefore, in one or more configurations, the indoor unit 120 can be either a furnace or an air handler, since both types of systems include at least a blower and an indoor evaporator coil. Furthermore, the indoor evaporator coil 124 can be positioned adjacent to the blower 121, so that when the blower 121 blows air into the indoor unit 120, the air is expelled through the evaporator coil 124. Furthermore, in one or more configurations, the blower 121 may include an extractor 122 and a blower motor 123. By way of example, in one or more configurations, the blower motor 123 may be a constant torque motor, while in other configurations, the blower motor 123 may be a permanent split capacitor (PSC) motor. The blower motor 123 may be mechanically coupled to the extractor 122 so that when the blower motor 123 is switched on, the extractor 122 is configured to rotate and cause airflow out of the blower 121 and through the indoor evaporator coil 124. The indoor evaporator coil 124 may be configured to receive the A2L refrigerant on the inside of the coil, while the air from the blower 121 is blown across the outside of the coil, allowing heat to be exchanged between the A2L refrigerant and the air, or vice versa.The A2L refrigerant, after cooling or heating the air, can return to the outdoor unit 130, where it will undergo the reverse heat exchange process before returning to the indoor evaporator coil 124. In addition, the indoor unit 120 is configured to distribute the air blown from the blower 121 and through the indoor evaporator coil 124 to the rooms inside 111 of building 110 by means of the force of the blower 121. Ala / a / zu^o / uuoouu The indoor unit 120 may also include a transformer 125 and an indoor control board 126. The transformer 125 may be directly electrically coupled and configured to provide 24-volt AC power to the A2L 150 control board. Additionally, the indoor control board 126 may be electrically coupled to the A2L 150 control board so that the indoor control board 126 can receive 24-volt AC power indirectly from the transformer 125. Furthermore, the indoor control board 126 may be electrically coupled to at least the blower motor 123 and the thermostat 140. In one or more configurations, the transformer 125 may be configured to indirectly provide 24-volt AC power to both the blower motor 123 and the thermostat 140 via the indoor control board 126 and the A2L 150 control board. In one or more configurations, the motor The blower has its own power source.Therefore, although the 24-volt AC power received by the blower motor does not turn on blower motor 123, the 24-volt AC signal is needed to turn on blower motor 123. By way of example only, in one or more modes, indoor control board 126 can be configured to supply power to thermostat 140, thermostat 140 can be configured to send a signal to indoor control board 126 to turn on blower motor 123, and indoor control board 126 can be configured to supply power to blower motor 123 to turn it on. Furthermore, the outdoor unit 130 can be located outside 112 of building 110 and configured to use the outside environment to reheat or cool the A2L refrigerant after it has passed through the indoor evaporator coil 124. The outdoor unit 130 may include, but is not limited to, a heat pump or an air conditioner. Whether the outdoor unit 130 is a heat pump or an air conditioner, it may include a compressor (not shown), an outdoor coil (not shown), and an outdoor control board 131. The outdoor unit 130 can be configured to receive power through the outdoor control board 131, which in turn is configured to receive power from the transformer 125 via the thermostat 140, the indoor control board 126, and the A2L control board 150.By way of example only, in one or more modes, the outdoor control board 131 can be configured to receive power and control signals from the thermostat 140, so that the outdoor control board 131 can turn on the capacitor after receiving a signal from the thermostat 140 to do so. With reference to Figure 1, the A2L 170 sensor can be configured in one or more modes to detect an A2L refrigerant leak and send a signal to report it. In one or more modes, the A2L 170 sensor can be configured to detect an A2L refrigerant leak using one of several methods, including at least detecting a quantity or concentration of A2L refrigerant in the air that exceeds a leak threshold. The A2L 170 sensor can be electrically coupled and communicate with the A2L 150 control board. In one or more modes, the A2L 170 sensor can be electrically coupled to the A2L 150 control board by means of a first sensor connector 157. The A2L 170 sensor can be configured to communicate to the A2L 150 control board that the A2L 170 sensor is connected to the system and functioning correctly.Furthermore, when the A2L 170 sensor detects an A2L refrigerant leak, it can report the leak to the A2L 150 control board, which can be configured to receive the signal and perform the safety measures required by A2L safety standards. In one or more configurations, the A2L 170 sensor and the A2L 150 control board can be electrically coupled via an RS-485 bus; however, a person skilled in the art will understand that any type of electrical connection that allows the A2L 170 sensor to send a signal to the A2L 150 control board can be used. While the A2L 170 sensor is depicted as electrically and communicatively coupled to the A2L 150 control board via a wired connection, a person skilled in the art will understand that the A2L 170 sensor can be communicatively coupled to the A2L 150 control board wirelessly. In one or more modes, the A2L 170 sensor can be communicatively coupled to the A2L 150 control board by any wireless means, such as Wi-Fi or Bluetooth. Furthermore, in one or more configurations, the A2L 170 sensor may be arranged inside the indoor unit 120 to detect an A2L refrigerant leak occurring within the indoor evaporator coil 124 of the HVAC system 100. As depicted, in one or more configurations, the A2L 170 sensor may be positioned directly against the indoor evaporator coil to minimize the time it takes for the A2L 170 sensor to detect an A2L refrigerant leak. Additionally, although the A2L 170 sensor is depicted as being inside the indoor unit 120, a person skilled in the art will understand that the A2L 170 sensor may also be arranged inside the outdoor unit 130.Furthermore, while only one sensor is shown, a person skilled in the art will understand that multiple sensors can be incorporated into the HVAC system to ensure that an A2L refrigerant leak is detected and that the required safety measures are taken within the time frame stipulated by A2L safety standards. For example, a person skilled in the art will understand that the HVAC system may include two A2L sensors, with both A2L sensors located inside the indoor unit, both A2L sensors located inside the outdoor unit, or one A2L sensor located inside each of the indoor and outdoor units.Therefore, a person skilled in the art will understand that in one or more modes, a plurality of A2L sensors may be placed within the HVAC system with one or more A2L sensors disposed within the indoor unit and / or one or more A2L sensors disposed within the outdoor unit as deemed necessary to ensure that an A2L refrigerant leak is detected and the required A2L safety measures are taken within the time required by A2L safety standards. Furthermore, with reference to Figure 1, in one or more configurations, the A2L 150 control board may be located inside the indoor unit 120. However, a person skilled in the art will understand that, in one or more configurations, the A2L 150 control board may be located outside the indoor unit 120 and connected to or adjacent to the indoor unit 120. Additionally, besides being electrically coupled to the transformer 125, the indoor control board 126, and the A2L 170 sensor, as explained above, the A2L 150 control board may be electrically coupled to the blower motor 123.In one or more modes, the A2L 150 control board can be configured to send a signal to the blower motor 123 to operate by means of a 24-volt AC line connected to an input wire 128 on the blower motor 123, if the blower motor 123 is a constant torque motor, or by means of a line voltage supplied to the input wire 128 of the blower motor 123, if the blower motor 123 is a PSC motor. In one or more configurations, the A2L 150 control board may include a power source 151, a power input contact point 152, a first relay 153, a first power disconnect contact point 154, a second relay 155, a second power off contact point 156, a first sensor connector 157, a second sensor connector 158, a buzzer 159, a light-emitting diode (LED) 160, a dry contact relay 161, a first and second fan contact point 162a and 162b, and a fuse 163. The power source 151 may be coupled to the circuitry on the A2L 150 control board so that the A2L control board can open and close at least the first relay 153, the second relay 154, and the dry contact relay 161.Furthermore, in one or more configurations, the first relay 153 can be electrically positioned between the power input contact point 152 and the first power disconnect contact point 154, such that when the first relay 153 is open, power from the power input contact point 152 does not reach the first power disconnect contact point 154. Additionally, the fuse 163 can be electrically positioned between the power input contact point 152 and the first relay 153. Similarly, in one or more configurations, the second relay 155 can be electrically positioned between the power contact point 152 and the second power disconnect contact point 156, such that when the second relay 155 is open, power from the power contact point 152 does not reach the second power disconnect contact point 156.Additionally, fuse 163 can be electrically connected between the power input contact point 152 and the second relay 155. For example, in one or more modes, when the first relay 153 is open, the second relay 155 is closed, and when the second relay 155 is open, the first relay 153 is closed. Furthermore, in one or more modes, in the default state, the first relay 153 is open and the second relay 155 is closed. Ala / a / zu^o / uuoouu In one or more configurations, the transformer 125 may be electrically coupled to the power input contact 152, the first power disconnect contact 154 may be electrically coupled to the indoor control board 126, and the second power disconnect contact 156 may be electrically coupled to the blower motor 123. Figure 1 shows a default state of the A2L control board 150, where 24-volt AC power from the transformer 125 is directed to the blower motor 123, causing it to operate. Furthermore, in one or more configurations, if the A2L control board 150 fails, all relays return to their default state, and therefore, if the A2L control board 150 fails, power will be directed to the blower motor 123.Furthermore, in one or more modes, when the A2L 150 control board is switched on, the second relay 154 opens immediately to prevent the blower motor 123 from running unnecessarily. Additionally, after the A2L 150 control board is switched on, when the system is ready to operate, the first relay 152 closes, switching on the HVAC system 100. Furthermore, in one or more configurations, the power supply 151 can be connected to the first sensor connector 157 and the second sensor connector 158 separately. Therefore, in one or more configurations, the A2L control board 150 can separately test one or more A2L sensors 170 before closing the first relay 153 and powering up the HVAC system 100. This allows the A2L control board 150 to ensure that the sensors 170 are functioning correctly and that there are no A2L refrigerant leaks before starting the system. Although two separate sensor connectors are depicted, a person skilled in the art will understand that the A2L control board may instead include a sensor signal input contact and a sensor signal output contact, and the one or more sensors may operate in series rather than in parallel. Therefore, when the A2L 150 control board receives a signal from the A2L 170 sensor indicating an A2L refrigerant leak, the A2L 150 control board can be configured to carry out the safety measures required by A2L safety standards. More specifically, in one or more modes, if a leak is detected, the A2L 150 control board can be configured to cut power to the indoor control board 126 by opening the first relay 153, while directing power directly to the blower motor 123 by closing the second relay 155. Since the indoor unit 120, thermostat 140, and outdoor unit 130 receive power from the indoor control board 126, when the A2L sensor detects an A2L refrigerant leak and the A2L 150 control board cuts power to the indoor control board 126, the entire HVAC system 100, in addition to the blower motor 123, is configured to lose power and shut down.This allows the HVAC 100 system to meet A2L safety requirements within the required time after the detection of an A2L refrigerant leak. iA / a / ¿u¿ó / uuoouu Furthermore, as discussed previously, in one or more configurations, the A2L 150 control board may include a buzzer 159, an LED 160, a dry contact relay 161, and first and second fan contact points 162a and 162b. In one or more configurations, the dry contact relay 161 may be electrically coupled to a fan (not shown), such that when the A2L 150 control board receives an A2L refrigerant leak signal from the A2L sensor 170, the dry contact relay 161 will switch and turn on the fan. Additionally, in one or more configurations, when the A2L control board receives an A2L refrigerant leak signal from the A2L sensor, the LED 160 and the buzzer 159 will be energized. Upon receiving power, LED 160 will display an error code and buzzer 159 will sound to give visual and audible alarms that the HVAC 100 system is experiencing an A2L refrigerant leak. With reference now to Figure 2, a flow diagram of one modality of a method 200 for installing and operating a non-communicating HVAC system using an A2L refrigerant is illustrated, as described above with respect to Figure 1, according to one or more modalities.Starting with an HVAC system 100 in which the indoor unit 120 has been disposed of inside 111 of a building 110, the outdoor unit 130 has been disposed of outside 112 of the building 110, the indoor control board 126 has been electrically coupled to the thermostat 140 and a blower motor 123 of the blower 121, and the outdoor control board 131 has been electrically coupled to the thermostat 140, method 200 may include one or more of the following: (step 210) installing the A2L control board 150 and the A2L sensor 170 in the HVAC system 100, (step 220) testing the A2L sensor 170, (step 230) starting operation of the HVAC system 100, (step 240) checking for refrigerant leaks A2L, and (stage 250) taking safety measures upon detecting an A2L refrigerant leak. In step 210, an A2L 150 control board and an A2L 170 sensor can be installed in the HVAC system 100. The installation of the A2L 150 control board and the A2L 170 sensor may include, at least, (step 211) physically attaching the A2L 170 sensor to the indoor evaporator coil 124 of the indoor unit 120, (step 212) electrically attaching the A2L 170 sensor to the A2L 150 control board, (step 213) electrically attaching the A2L 150 control board to the indoor control board 126, (step 214) electrically attaching the A2L 150 control board to the blower motor 123, (step 215) electrically attaching the A2L control board 150 to transformer 125, and (stage 216) turn on the A2L control board 150 and open the second relay 155. In one or more configurations, in step 211, the A2L 170 sensor can be placed inside the indoor unit 120 so that it is adjacent to or connected to the indoor evaporator coil 124, enabling the A2L 170 sensor to detect an A2L refrigerant leak if one occurs. Furthermore, in step 212, the A2L 170 sensor can be electrically coupled to the A2L 150 control board, allowing bidirectional communication between the A2L 170 sensor and the A2L 150 control board. For example, in one or more configurations, an A2L 170 sensor can be electrically coupled to a sensor connector 157 on the A2L 150 control board via an RS-485 bus. An expert in the field will appreciate that in other configurations, any other electrical coupling that allows bidirectional communication between the A2L 170 sensor and the A2L 150 control board can be used. In step 213, the A2L 150 control board can be electrically coupled to the internal control board 126. In one or more configurations, a cable capable of carrying 24-volt AC power can be electrically coupled at one end to a power input terminal inside the internal control board 126 and at the other end to a first power disconnect contact 154 of the A2L 150 control board. Therefore, once a transformer 125 is electrically coupled to the A2L 150 control board, providing 24-volt AC power to the A2L 150 control board, and a first relay 153 is closed, the internal control board 126 can receive the 24-volt AC power. In step 214, the A2L 150 control board can be electrically coupled to the blower motor 123. In one or more configurations, a cable capable of carrying 24-volt AC power can be electrically connected at one end to an input cable 128 on the blower motor 123 and at the other end to a second power disconnect contact 156 on the A2L 150 control board. Therefore, once a transformer 125 is electrically coupled to the A2L 150 control board, providing 24-volt AC power to the A2L 150 control board, the blower motor 123 can receive 24 volts of AC power as long as the second relay 155 is closed. In one or more configurations, the default state for the second relay 155 may be closed. However, while the HVAC system is running and no A2L leak is detected, the second relay 155 remains open.Additionally, in the event of an A2L refrigerant leak, the second relay 155 closes so that the blower motor 123 can receive 24-volt AC power even though the rest of the HVAC system is off. In step 215, the A2L 150 control board can be electrically coupled to the transformer 125. In one or more configurations, a cable capable of carrying 24-volt AC power can be electrically coupled at one end to a power disconnect terminal inside the transformer 125 and at the other end to a power input contact 152 on the A2L 150 control board. Therefore, once the transformer 125 is electrically coupled to the A2L 150 control board, the A2L control board has 24-volt AC power that it can distribute to the indoor control board 126 or to the blower motor 123. Ala / a / zu^o / uuoouu In stage 216, the A2L 150 control board can be powered on and the second relay 155 can be opened. In one or more modes, when the A2L 150 control board is powered on, the relays are in their default state, which includes the second relay 155 being closed. Therefore, to ensure that power is not unnecessarily diverted to the blower motor 123, in one or more modes, when the A2L 150 control board is powered on, the A2L 150 control board opens the second relay 155. In stage 220, the A2L 170 sensor can be evaluated to confirm it is functioning correctly. Once electrically coupled to the A2L 150 control board in one or more modes, the A2L 170 sensor can perform an internal diagnostic check to ensure it is functioning correctly and can detect an A2L refrigerant leak. If the diagnostic check is successful, the A2L 170 sensor can communicate the successful check to the A2L 150 control board, which can then begin operating the HVAC 100 system. If the A2L 170 sensor fails the diagnostic check, it will communicate the failed check to the A2L 150 control board, which will remain in its default settings, preventing the HVAC 100 system from operating until the A2L sensor is repaired or replaced. In stage 230, the A2L 150 control board can begin operating the HVAC 100 system. To begin operation, in one or more modes, the A2L 150 control board can close the first relay 153. Closing the first relay 153 allows the 24-volt AC power that the A2L 150 control board receives from transformer 125 to pass to the indoor control board 126 and power the rest of the HVAC 100 system. In step 240, while the HVAC system is operating in one or more modes, the A2L 170 sensor can check for A2L refrigerant leaks. The A2L 170 sensor can continuously check for A2L refrigerant leaks while the HVAC 100 system is running. If a check is negative for an A2L refrigerant leak, the A2L 170 sensor repeats step 240. However, if the A2L 170 sensor detects an A2L leak, it reports the leak to the A2L control board, and the HVAC system proceeds to step 250. At stage 250, the HVAC 100 system, through the A2L 150 control board, can perform safety measures to eliminate the threat of detected A2L refrigerant leak. Specifically, HVAC system 100 can (step 252) open the first relay 153, (step 253) close the second relay 155, (step 254) close the dry contact relay 161, (step 256) turn on the LED 160, and (step 258) turn on the buzzer 159. In step 252, opening the first relay 153 prevents the 24-volt AC power that the A2L control board 150 receives from the transformer 125 from passing to the indoor control board 126. Removing the 24-volt AC power from the indoor control board 126, in turn, removes power from the entire HVAC system 100 since the blower motor 123, thermostat 140, and outdoor unit 130 are configured to receive power. 24-volt AC, either directly or indirectly, from the internal control board 126.Additionally, in step 253, closing the second relay 155 causes the 24-volt AC power received by the A2L control board 150 from the transformer 125 to flow directly to the blower motor 123. This 24-volt AC power going directly to the blower motor 123 causes the blower motor 123 to operate even though the indoor control board 126 and thermostat 140 are unpowered and off. Furthermore, although listed as separate steps, a person skilled in the art will appreciate that in one or more configurations, step 252 or step 253 may occur before the other, or in other configurations, steps 252 and 253 may occur simultaneously. Additionally, a person skilled in the art will appreciate that both steps 252 and 253 can be completed within the time required after the detection of an A2L refrigerant leak, as required by A2L safety standards. In stage 254, in one or more modes, the A2L 150 control board can close the dry contact relay 161, which turns on a fan. In one or more modes, a fan can be connected to the HVAC 100 system via the first and second fan contact points 162a and 162b on the A2L 150 control board. Therefore, when the A2L 170 sensor detects a leak, the A2L 150 control board can close the dry contact relay 161, allowing power to flow directly to the fan and turn it on. Additionally, in step 256, when the A2L 150 control board receives the A2L refrigerant leak communication, the A2L 150 control board can supply power to LED 160. Also, in step 258, when the A2L 150 control board receives the A2L refrigerant leak communication, the A2L 150 control board can supply power to buzzer 159. Therefore, in one or more modes, in response to a communication from the A2L 170 sensor that an A2L refrigerant leak has been detected, the A2L 150 control board may shut down the entire HVAC 100 system, except for the blower motor 123, which is on, turn on a fan if the HVAC 100 system has one, and turn on the visual and audible alarms that an A2L refrigerant leak has been detected. Although Method 200 is described with respect to an HVAC 100 system that includes a single A2L 170 sensor, a person skilled in the art will understand that any number of sensors can be used in the system and the method may include electrically coupling the additional sensors to the control board, evaluating the additional sensors, and communicating with the additional sensors as the additional sensors check for A2L refrigerant leaks. Figure 3 shows a communicating HVAC system using an A2L refrigerant, according to one or more modes. In one or more modes, an A2L system can be used. HVAC 300 to distribute cooled or heated air throughout a building 310 to adjust the ambient air temperature inside 311 of the building 310. The HVAC system may include an indoor unit 320, an outdoor unit 330, a thermostat 340, an A2L control board 350, an A2L sensor 370, an outdoor relay 380 and a high pressure switch 390. Generally, in one or more configurations, the indoor unit 320 can be seamlessly coupled to the outdoor unit 330 so that an A2L refrigerant can flow between the indoor unit 320 and the outdoor unit 330 to cool or heat the air inside the indoor unit 320. Additionally, in one or more configurations, both the indoor unit 320 and the outdoor unit 330 can be communicatively coupled to each other via an RS485 communication system. The thermostat 340 can be either a communication or non-communication thermostat and can be electrically coupled to the indoor unit 320 via a 24-volt AC connection or an R-485 communication system. Furthermore, in one or more configurations, the A2L control board 350 can be electrically coupled directly to the indoor unit 320 and electrically coupled indirectly to the outdoor unit 330 via the outdoor relay 380 and the high-pressure switch 390.The A2L 350 control board can act as a power supply path for the 320 indoor unit and can be configured to cut off power to certain parts of the 320 indoor unit if there is an A2L refrigerant leak in the system. Additionally, the A2L 350 control board can be configured to shut down the outdoor unit by establishing electrical connections between the A2L 350 control board, the 380 outdoor relay, the 390 high-pressure switch, and the 320 outdoor unit. Furthermore, the A2L 370 sensor can be physically installed inside the 320 indoor unit and electrically connected to the A2L 350 control board. The A2L 370 sensor can be configured to send signals to the A2L 350 control board when an A2L refrigerant leak is detected. In one or more configurations, the indoor unit 320 can be located inside building 310, unit 311. The indoor unit 320 can be configured to distribute either cooled or heated air to the rooms inside building 310, unit 311. The indoor unit 320 can be any type of HVAC system that includes a blower 321 and a heat exchanger 327 having an indoor evaporator coil 324. Therefore, in one or more configurations, the indoor unit 320 can be either a furnace or an air handler, since both types of systems include at least a blower and an indoor evaporator coil. Furthermore, the indoor evaporator coil 324 can be positioned adjacent to the blower 321, so that when the blower 321 blows air into the indoor unit 320, the air is expelled through the evaporator coil 324. Furthermore, in one or more embodiments, the blower 321 may include an extractor 322 and a blower motor 323. By way of example, in one or more embodiments, the blower motor 323 may be a constant torque motor, while in other embodiments, the blower motor 323 may be a permanent split capacitor (PSC) motor. The blower motor 323 can be mechanically coupled to the extractor 322 so that when the blower motor 323 is switched on, the extractor 322 is set to rotate and cause air movement out of the blower 321 and through the indoor evaporator coil 324. The indoor evaporator coil 324 can be set up to receive the A2L refrigerant on the inside of the coil, while the air from the blower 321 is blown across the outside of the coil, allowing heat to be exchanged between the A2L refrigerant and the air or vice versa.The A2L refrigerant, after cooling or heating the air, can return to the outdoor unit 330, where it will undergo the reverse heat exchange process before returning to the indoor evaporator coil 324. In addition, the indoor unit 320 is configured to distribute the air blown from the blower 321 and through the indoor evaporator coil 324 to the rooms inside 311 of the building 310 by means of the force of the blower 321. The indoor unit 320 may also include a transformer 325 and an indoor control board 326. The transformer 325 may be directly electrically coupled and configured to provide 24-volt AC power to the A2L 350 control board. Additionally, the indoor control board 326 may be electrically coupled to the A2L 350 control board so that the indoor control board 326 can receive 24-volt AC power indirectly from the transformer 325. Furthermore, the indoor control board 326 may be electrically coupled to at least the blower motor 323 and the thermostat 340. In one or more configurations, the transformer 325 may be configured to indirectly provide 24-volt AC power to the blower motor 323 via the indoor control board 326 and the A2L 350 control board. In one or more configurations, the blower motor has its own power source. energy.Therefore, although the 24-volt AC power received by the blower motor does not turn on blower motor 323, the 24-volt AC signal is needed to turn on blower motor 323. In addition, the indoor control board 326 can be electrically coupled to the thermostat by means of a 24-volt AC power connection or by means of an R-485 communication system depending on whether the thermostat is a communication or non-communication thermostat, respectively. In addition, the outdoor unit 330 can be placed outside 312 of building 310 and configured to use the outside environment to reheat or cool the A2L refrigerant after it has passed through the indoor evaporator coil 324. The outdoor unit 330 may include, but is not limited to, a heat pump or an air conditioner. Whether the outdoor unit 330 is a heat pump or an air conditioner, it may include a compressor (not shown), an outdoor coil (not shown), and an outdoor control board 331. The outdoor unit 330 can be configured to communicate with the indoor unit 320 via the RS-485 communication system between the indoor control board 326 and the outdoor control board 331. Furthermore, the outdoor control board 331 can be electrically coupled to the A2L 350 control board as discussed below. With reference to Figure 3, in one or more modes, the A2L 370 sensor can be configured to detect an A2L refrigerant leak and send a signal to report it. In one or more modes, the A2L 370 sensor can be configured to detect an A2L refrigerant leak by one of several methods, including at least detecting a quantity or concentration of A2L refrigerant in the air that exceeds a leak threshold. The A2L 370 sensor can be electrically coupled to and communicate with the A2L 350 control board. In one or more modes, the A2L 370 sensor can be electrically coupled to the A2L 350 control board by means of a first sensor connector 357. The A2L 370 sensor can be configured to communicate to the A2L 350 control board that the A2L 370 sensor is connected to the system and functioning correctly.Furthermore, when the A2L 370 sensor detects an A2L refrigerant leak, it can report the leak to the A2L 350 control board, which can be configured to receive the signal and perform the safety measures required by A2L safety standards. In one or more configurations, the A2L 370 sensor and the A2L 350 control board can be electrically coupled via an RS-485 bus; however, a person skilled in the art will understand that any type of electrical connection that allows the A2L 370 sensor to send a signal to the A2L 350 control board can be used. While the A2L 370 sensor is depicted as electrically and communicatively coupled to the A2L 350 control board via a wired connection, a person skilled in the art will understand that the A2L 370 sensor can be communicatively coupled to the A2L 350 control board wirelessly. In one or more modes, the A2L 370 sensor can be communicatively coupled to the A2L 350 control board by any wireless means, such as Wi-Fi or Bluetooth. Furthermore, in one or more configurations, the A2L 370 sensor can be arranged inside the indoor unit 320 to detect an A2L refrigerant leak occurring within the indoor evaporator coil 324 of the HVAC system 300. As depicted, in one or more configurations, the A2L 370 sensor can be positioned directly against the indoor evaporator coil to minimize the time it takes for the A2L 370 sensor to detect an A2L refrigerant leak. Additionally, although the A2L 370 sensor is depicted as being inside the indoor unit 320, a person skilled in the art will understand that the A2L 370 sensor can also be arranged inside the outdoor unit 330.Furthermore, although only one sensor is shown, a person skilled in the art will understand that multiple sensors can be incorporated into the HVAC system to ensure that an A2L refrigerant leak is detected and that the required safety measures are taken within the time frame stipulated by A2L safety standards. For example, a person skilled in the art will understand that the HVAC system may include two A2L sensors. A2L, with both A2L sensors arranged inside the indoor unit, both A2L sensors arranged inside the outdoor unit, or one A2L sensor arranged inside each of the indoor and outdoor units. Therefore, a person skilled in the art will understand that in one or more of these configurations, a plurality of A2L sensors may be placed within the HVAC system, with one or more A2L sensors arranged inside the indoor unit and / or one or more A2L sensors arranged inside the outdoor unit, as deemed necessary to ensure that an A2L refrigerant leak is detected and the required safety measures are taken within the time frame required by A2L safety standards. Furthermore, with reference to Figure 3, in one or more configurations, the A2L 350 control board may be located inside the indoor unit 320. However, a person skilled in the art will understand that, in one or more configurations, the A2L 350 control board may be located outside the indoor unit 320 and connected to or adjacent to the indoor unit 320. Additionally, besides being electrically coupled to the transformer 325, the indoor control board 326, and the A2L 370 sensor, as explained above, the A2L 350 control board may be electrically coupled to the outdoor control board 331 by means of the outdoor relay 380 and the high-pressure switch 390. In one or more configurations, the outdoor relay 380 and the high-pressure switch 390 may be electrically coupled in series between the A2L 350 control board and the outdoor control board 331. 331.In one or more configurations, the outdoor relay 380 can be electrically coupled directly to the A2L 350 control board so that the outdoor relay 380 is configured to open upon receiving a 24-volt AC power signal from the A2L 350 control board. Additionally, in one or more configurations, the high-pressure switch 390 is electrically coupled to the outdoor control board 331 so that when the high-pressure switch 390 opens, the outdoor unit 330 shuts down completely. Furthermore, in one or more configurations, the opening of the outdoor relay 380 causes the high-pressure switch 390 to open, resulting in the outdoor unit 330 shutting down completely. In one or more configurations, the A2L 350 control board may include a power source 351, a power input contact point 352, a first relay 353, a first power disconnect contact point 354, a second relay 355, a second power off contact point 356, a first sensor connector 357, a second sensor connector 358, a buzzer 359, an LED 360, a dry contact relay 361, a first and second fan contact point 362a and 362b, and a fuse 363. The power source 351 may be coupled to the circuitry on the A2L 350 control board so that the A2L control board can open and close at least the first relay 353, the second relay 354, and the dry contact relay 361.Furthermore, in one or more configurations, the first relay 353 can be electrically positioned between the power input contact point 352 and the first power disconnect contact point 354, such that when the first relay 353 is open, power from the power input contact point 352 does not reach the first power disconnect contact point 354. Additionally, the fuse 363 can be electrically positioned between the power input contact point 352 and the first relay 353. Similarly, in one or more configurations, the second relay 355 can be electrically positioned between the power contact point 352 and the second power disconnect contact point 356, such that when the second relay 355 is open, power from the power contact point 352 does not reach the second power disconnect contact point 356.Additionally, fuse 363 can be electrically connected between the power input contact point 352 and the second relay 355. For example, in one or more modes, when the first relay 353 is open, the second relay 355 is closed, and when the second relay 355 is open, the first relay 353 is closed. Furthermore, in one or more modes, in the default state, the first relay 353 is open and the second relay 355 is closed. In one or more configurations, transformer 325 may be electrically coupled to power input contact 352, the first power disconnect contact 354 may be electrically coupled to the indoor control board 326, and the second power disconnect contact 356 may be electrically coupled to the outdoor relay 380. Figure 3 shows a default state of the A2L 350 control board, where 24-volt AC power from transformer 325 is directed to the outdoor relay 380. Furthermore, in one or more configurations, if the A2L 350 control board fails, all relays return to their default state. Therefore, if the A2L 350 control board fails, power will be directed to the outdoor relay 380, causing it to open, thereby opening the high-pressure switch 390 and shutting down the outdoor unit 330.Furthermore, in one or more modes, when the A2L 150 control board is switched on, the second relay 154 opens immediately to prevent power from being unnecessarily supplied to the external relay 380 before it is needed. Additionally, after the A2L 350 control board is switched on, when the system is ready to operate, the first relay 352 closes, switching on the HVAC 300 system. Furthermore, in one or more configurations, the power supply 351 can be connected to the first sensor connector 357 and the second sensor connector 358 separately. Therefore, in one or more configurations, the A2L control board 350 can separately test one or more A2L sensors 370 before closing the first relay 353 and powering up the HVAC system 300. This allows the A2L control board 350 to ensure that the sensors 370 are functioning correctly and that there are no A2L refrigerant leaks before starting the system. Although two separate sensor connectors are depicted, a person skilled in the art will understand that the A2L control board may instead include a sensor signal input contact and a sensor signal output contact, and the one or more sensors may operate in series instead of in parallel. Therefore, when the A2L 350 control board receives a signal from the A2L 370 sensor indicating an A2L refrigerant leak, the A2L 350 control board can be configured to implement the safety measures required by A2L safety standards. More specifically, in one or more modes, if a leak is detected, the A2L 350 control board can be configured to cut power to the indoor control board 326 by opening the first relay 353, while simultaneously directing power directly to the outdoor relay 380 by closing the second relay 355. Since the indoor unit 320 receives power from the indoor control board 326, when the A2L sensor detects an A2L refrigerant leak and the A2L 350 control board cuts power to the indoor control board 326, the indoor unit 320 is configured to lose power and shut down.Additionally, in one or more modes, the blower motor 323 can be configured so that if it loses the signal from the indoor control board 326, it will start and remain on. Therefore, when the A2L control board 350 disconnects power to the indoor control board 326 in response to a detected A2L refrigerant leak, the blower motor 323 will lose the signal from the indoor control board 326 and start. Furthermore, closing the second relay 355 in response to an detected A2L refrigerant leak causes power to be diverted directly to the outdoor relay 380. Additionally, in one or more modes, the power diverted directly to the outdoor relay 380 causes the outdoor relay 380 to open. Furthermore, the opening of the outdoor relay 380 is configured to cause the high-pressure switch 390 to open.Additionally, the outdoor unit 330 is configured to shut down completely if the high-pressure switch 390 opens. Therefore, the opening of the second relay 355 is configured to completely shut down the outdoor unit 330. This allows the HVAC system 300 to meet A2L safety requirements within the required time after the detection of an A2L refrigerant leak. While Figure 3 depicts one or more embodiments of the present invention that utilize an outdoor relay 380 and a high-pressure switch 390 to shut down the outdoor unit in the event of an A2L refrigerant leak, a person skilled in the art will understand that any means of shutting down the outdoor unit compressor will function to adequately meet the A2L safety requirements. By way of example, in one or more embodiments, the HVAC system may include an A2L control board that is electrically coupled to a contactor, wherein the contactor is configured to contact the outdoor control board so that the outdoor unit shuts down in the event of an A2L refrigerant leak.In addition, in other configurations, the A2L control board can be communicatively coupled to the outdoor control board via RS-485 system communication, enabling the A2L control board to instruct the outdoor control board to shut down the outdoor unit if an A2L leak is detected. Furthermore, in one or more configurations, the A2L control board can be electrically coupled to a relay, where the relay is positioned between the outdoor control board and the outdoor unit's compressor. When the relay opens, power from the outdoor control board is cut off to the compressor, and the compressor shuts down. Furthermore, while in one or more modes the A2L control board uses a 24-volt AC signal to communicate with the outdoor relay to shut down the outdoor unit, a person skilled in the art will understand that, in one or more modes, the A2L control board can send digital signals to the outdoor relay. A person skilled in the art will understand that these digital signals can also be used with a contactor or any other relay connected to the outdoor control board to shut down the outdoor unit. Additionally, in one or more modes, the A2L control board can be wirelessly connected to the outdoor control board so that wireless signals can be used to shut down the outdoor unit. Furthermore, as discussed previously, in one or more configurations, the A2L 350 control board may include a buzzer 359, an LED 360, a dry contact relay 361, and first and second fan contact points 362a and 362b. In one or more configurations, the dry contact relay 361 may be electrically coupled to a fan (not shown), such that when the A2L 350 control board receives an A2L refrigerant leak signal from the A2L sensor 370, the dry contact relay 361 will switch and turn on the fan. Additionally, in one or more configurations, when the A2L control board receives an A2L refrigerant leak signal from the A2L sensor, the LED 360 and the buzzer 359 will be energized. Upon receiving power, LED 360 will display an error code and buzzer 359 will sound to give visual and audible alarms that the HVAC 300 system is experiencing an A2L refrigerant leak. With reference now to Figure 4, a flow diagram of one modality of a Method 400 for the installation and operation of a communicating HVAC system using an A2L refrigerant is illustrated, as described above with respect to Figure 3, according to one or more modalities.Beginning with an HVAC system 300 in which the indoor unit 320 has been disposed of inside 311 of a building 310, the outdoor unit 330 has been disposed of outside 312 of the building 310, the indoor control board 326 has been electrically coupled to the thermostat 340 and a blower motor 323 of the blower 321, and the outdoor control board 331 has been communicatively coupled to the indoor control board 326, method 400 may include one or more of the following: (step 410) installing the A2L control board 350 and the A2L sensor 370 in the HVAC system 300, (step 420) testing the A2L sensor 370, (step 430) starting operation of the HVAC system 300, (step 440) checking for leaks of A2L refrigerant, and (stage 450) taking safety measures upon detecting a leak of A2L refrigerant. In step 410, an A2L 350 control board and an A2L 370 sensor can be installed in the HVAC 300 system. Installation of the A2L 350 control board and the A2L 370 sensor may include, at least, (step 411) physically attaching the A2L 370 sensor to the indoor evaporator coil 324 of the indoor unit 320, (step 412) electrically attaching the A2L 370 sensor to the A2L 350 control board, (step 413) electrically attaching the A2L 350 control board to the indoor control board 326, (step 414) electrically attaching the A2L 350 control board to the outdoor control board 331, (step 415) electrically attaching the control board of A2L 350 to transformer 325, and (stage 416) turn on the A2L 150 control board and open the second relay 155. In one or more configurations, in step 411, the A2L 370 sensor can be placed inside the indoor unit 320 so that it is adjacent to or connected to the indoor evaporator coil 324, enabling the A2L 370 sensor to detect an A2L refrigerant leak should one occur. Additionally, in step 412, the A2L 370 sensor can be electrically coupled to the A2L 350 control board, allowing bidirectional communication between the A2L 370 sensor and the A2L 350 control board. For example, in one or more configurations, an A2L 370 sensor can be electrically coupled to a first sensor connector 357 on the A2L 350 control board via an RS-485 bus. An expert in the field will appreciate that in other configurations, any other electrical coupling that allows bidirectional communication between the A2L 370 sensor and the A2L 350 control board can be used. In stage 413, the A2L 350 control board can be electrically coupled to the internal control board 326. In one or more configurations, a cable capable of carrying 24-volt AC power can be electrically coupled at one end to a power input terminal inside the internal control board 326 and at the other end to a first power disconnect contact 354 of the A2L 350 control board. Thus, once a transformer 325 is electrically coupled to the A2L 350 control board, providing 24-volt AC power to the A2L 350 control board, and a first relay 353 is closed, the internal control board 326 can receive the 24-volt AC power. In step 414, the A2L 350 control board can be electrically coupled to the external control board 331. In one or more configurations, the high-pressure switch 390 can be electrically coupled to the external control board 331 such that when the high-pressure switch 390 opens, the external control board 331 is switched off. Additionally, the external relay 380 can be electrically coupled to the high-pressure switch 390 such that when the external relay opens, the high-pressure switch opens. Furthermore, the external relay 380 can be electrically coupled to a second power disconnect contact 356 of the A2L 350 control board by means of a cable capable of carrying 24-volt AC power.Therefore, once transformer 325 is electrically coupled to the A2L 350 control board, providing 24-volt AC power to the A2L 350 control board, closing the second relay 355 opens the outdoor relay 380, which opens the high-pressure switch 390, causing the outdoor control board 331 to shut down the outdoor unit 330. In one or more modes, the default setting for the second relay 355 may be closed; however, while the HVAC system is operating and no A2L leak is detected, the second relay 355 remains open. Furthermore, if an A2L refrigerant leak is detected, the second relay 355 closes, causing the outdoor unit 330 to shut down completely. In stage 415, the A2L 350 control board can be electrically coupled to the transformer 325. In one or more configurations, a cable capable of carrying 24-volt AC power can be electrically coupled at one end to a power disconnect terminal inside the transformer 325 and at the other end to a power input contact 352 on the A2L 350 control board. Therefore, once the transformer 325 is electrically coupled to the A2L 350 control board, the A2L control board has 24-volt AC power that it can distribute to the internal control board 326 or the external relay 380. In stage 416, the A2L 350 control board can be powered on and the second relay 355 can be opened. In one or more modes, when the A2L 350 control board is powered on, the relays are in their default state, which includes the second relay 355 being closed. Therefore, to ensure that power is not unnecessarily diverted to the blower motor 323, in one or more modes, when the A2L 350 control board is powered on, the A2L 350 control board opens the second relay 355. In step 420, the A2L 370 sensor can be evaluated to confirm it is functioning correctly. Once electrically coupled to the A2L 350 control board in one or more modes, the A2L 370 sensor can perform an internal diagnostic check to ensure it is functioning correctly and can detect an A2L refrigerant leak. If the diagnostic check is successful, the A2L 370 sensor can communicate the successful check to the A2L 350 control board, which can then begin operating the HVAC 300 system. If the A2L 370 sensor fails the diagnostic check, it will communicate the failed check to the A2L 350 control board, which will remain in its default settings, preventing the HVAC 300 system from operating until the A2L sensor is repaired or replaced. In step 430, the A2L 350 control board can begin operating the HVAC 300 system. To begin operation, in one or more modes, the A2L 350 control board can close the first relay 353. Closing the first relay 353 allows the 24-volt AC power that the A2L 350 control board receives from transformer 325 to pass to the indoor control board 326 and turn on the indoor unit 320. In step 440, while the HVAC system is operating in one or more modes, the A2L 370 sensor can check for A2L refrigerant leaks. The A2L 370 sensor can continuously check for A2L refrigerant leaks while the HVAC 300 system is running. If a check is negative for an A2L refrigerant leak, the A2L 370 sensor repeats step 440. However, if the A2L 370 sensor detects an A2L leak, it reports the leak to the A2L control board, and the HVAC system proceeds to step 450. At stage 450, the HVAC 300 system, through the A2L 350 control board, can perform safety measures to eliminate the threat of detected A2L refrigerant leak. Specifically, the HVAC system 300 can (step 452) open the first relay 353, (step 453) close the second relay 355, (step 454) close the dry contact relay 361, (step 456) turn on the LED 360, and (step 458) turn on the buzzer 359. In step 452, opening the first relay 353 prevents the 24-volt AC power that the A2L control board 350 receives from the transformer 325 from passing to the indoor control board 326, thus cutting off the 24-volt AC power to the indoor unit 320. As discussed earlier, disconnecting the power to the indoor unit 320 causes the blower motor 323 to lose its signal from the indoor control board 326, causing the blower motor 323 to turn on and remain on.Additionally, in step 453, closing the second relay 355 allows the 24-volt AC power supplied to the A2L control board 350 from transformer 325 to flow to the external relay 380. As discussed earlier, the 24-volt AC power directed to the external relay 380 causes it to open, which in turn opens the high-pressure switch 390, causing the external control board 331 to shut down completely. Furthermore, although listed as separate steps, a person skilled in the art will appreciate that in one or more configurations, either step 452 or step 453 may occur before the other, or in other configurations, steps 452 and 453 may occur simultaneously. Additionally, an expert in the technique will appreciate that both steps 452 and 453 can be completed within the required time after the detection of an A2L refrigerant leak as required by A2L safety standards. In stage 454, in one or more modes, the A2L 350 control board can close the dry contact relay 361, which turns on a fan. In one or more modes, a fan can be connected to the HVAC 300 system via the first and second fan contact points 362a and 362b on the A2L 350 control board. Therefore, when the A2L 370 sensor detects a leak, the A2L 350 control board can close the dry contact relay 361, allowing power to flow directly to the fan and turn it on. Additionally, in step 456, when the A2L 350 control board receives the A2L refrigerant leak communication, the A2L 350 control board can supply power to LED 360. Also, in step 458, when the A2L 350 control board receives the A2L refrigerant leak communication, the A2L 350 control board can supply power to buzzer 359. Therefore, in one or more modes, in response to a communication from the A2L 370 sensor that an A2L refrigerant leak has been detected, the A2L 350 control board may turn off the indoor unit 320 and the outdoor unit 330, except for the blower motor 323, which is turned on by the loss of signal from the indoor control board 326, turn on a fan if the HVAC system 300 has one, and turn on the visual and audible alarms that an A2L refrigerant leak has been detected. Although Method 400 is described with respect to an HVAC 300 system that includes a single A2L 370 sensor, a person skilled in the art will understand that any number of sensors can be used in the system and the method may include electrically coupling the additional sensors to the control board, evaluating the additional sensors, and communicating with the additional sensors as the additional sensors check for A2L refrigerant leaks. Figure 5 shows a non-communicating HVAC system using an A2L refrigerant, according to one or more modes. In one or more configurations, an HVAC system 500 can be used to distribute cooled or heated air throughout a building 510 to adjust the ambient air temperature within 511 of the building 510. The HVAC system may include an indoor unit 520, an outdoor unit 530, a thermostat 540, an A2L control board 550, and an A2L sensor 570. Generally, in one or more configurations, the indoor unit 520 can be fluidly coupled to the outdoor unit 530 so that an A2L refrigerant can flow between the indoor unit 520 and the outdoor unit 530 to cool or heat the air inside the indoor unit 520. Additionally, in one or more configurations, the indoor unit 520 can be electrically coupled indirectly to the thermostat 540, while the outdoor unit 530 can be electrically coupled directly to the thermostat 540.The 540 thermostat can be configured to use on / off signals for communication and control of the 520 indoor unit and the 530 outdoor unit. Additionally, in one or more modes, the A2L 550 control board can be electrically coupled directly between the 520 indoor unit and the 540 thermostat, so that any communication or signal between the two must pass through the A2L 550 control board. Therefore, in one or more modes, the A2L 550 control board can act as a power pass-through for parts of the 520 indoor unit, the 530 outdoor unit, and the 540 thermostat, and can be configured to block power supply to certain parts of the 520 indoor unit, the 530 outdoor unit, and the 540 thermostat if there is an A2L refrigerant leak in the system. In addition, an A2L 570 sensor can be physically placed inside the 520 indoor unit and electrically coupled to the A2L 550 control board.The A2L 570 sensor can be configured to send signals to the A2L 550 control board when an A2L refrigerant leak is detected. In one or more configurations, the indoor unit 520 can be located inside building 511. The indoor unit 520 can be configured to distribute either cooled or heated air to the rooms inside building 511. The indoor unit 520 can be any type of HVAC system that includes a blower 521 and a heat exchanger 527 having an indoor evaporator coil 524. Therefore, in one or more configurations, the indoor unit 520 can be either a furnace or an air handler, since both types of systems include at least a blower and an indoor evaporator coil. Furthermore, the indoor evaporator coil 524 can be located adjacent to the blower 521, so that when the blower 521 blows air into the indoor unit 520, the air is expelled through the evaporator coil 524. Furthermore, in one or more configurations, the blower 521 may include an extractor 522 and a blower motor 523. By way of example, in one or more configurations, the blower motor 523 may be a constant torque motor, while in other configurations, the blower motor 523 may be a permanent split capacitor (PSC) motor. The blower motor 523 may be mechanically coupled to the extractor 522 so that when the blower motor 523 is switched on, the extractor 522 is configured to rotate and cause airflow out of the blower 521 and through the indoor evaporator coil 524. The indoor evaporator coil 524 may be configured to receive the A2L refrigerant on the inside of the coil, while the air from the blower 521 is blown across the outside of the coil, allowing heat to be exchanged between the A2L refrigerant and the air, or vice versa.The A2L refrigerant, after cooling or heating the air, can return to the outdoor unit 530, where it will undergo the reverse heat exchange process before returning to the indoor evaporator coil 524. In addition, the indoor unit 520 is configured to distribute the air blown from the blower 521 and through the indoor evaporator coil 524 to the rooms inside 511 of the building 510 by means of the force of the blower 521. The indoor unit 520 may also include a transformer 525 and an indoor control board 526. The transformer 525 can be directly electrically coupled and configured to provide 24 volt AC power to the indoor control board 526. In addition, the indoor control board 526 can be electrically coupled to at least the A2L control board 550 and the blower motor 523. Furthermore, the outdoor unit 530 can be placed outside 512 of the building 510 and configured to use the outside environment to reheat or cool the A2L refrigerant after it has passed through the indoor evaporator coil 524. The outdoor unit 530 may include, but is not limited to, a heat pump or an air conditioner. Whether the outdoor unit 530 is a heat pump or an air conditioner, the outdoor unit 530 may include a compressor (not shown), an outdoor coil (not shown), and an outdoor control board 531. The outdoor unit 530 can be configured to receive power through the outdoor control board 531, which in turn is configured to receive power from the transformer 525 through the thermostat 540, the indoor control board 526, and the A2L control board 550.By way of example only, in one or more modes, the outdoor control board 531 can be configured to receive power and control signals from the thermostat 540, so that the outdoor control board 531 can turn on the capacitor after receiving a signal from the thermostat 540 to do so. With reference to Figure 5, in one or more modes, the A2L 570 sensor can be configured to detect an A2L refrigerant leak and send a signal to report it. In one or more modes, the A2L 570 sensor can be configured to detect an A2L refrigerant leak by one of several methods, including at least detecting a quantity or concentration of A2L refrigerant in the air that exceeds a leak threshold. The A2L 570 sensor can be electrically coupled to and communicate with the A2L 550 control board. In one or more modes, the A2L 570 sensor can be electrically coupled to the A2L 550 control board by means of a sensor connector 560. The A2L 570 sensor can be configured to communicate to the A2L 550 control board that the A2L 570 sensor is connected to the system and functioning correctly.Furthermore, when the A2L 570 sensor detects an A2L refrigerant leak, it can report the leak to the A2L 550 control board, which can be configured to receive the signal and perform the safety measures required by A2L safety standards. In one or more configurations, the A2L 570 sensor and the A2L 550 control board can be electrically coupled via an RS-485 bus; however, a person skilled in the art will understand that any type of electrical connection that allows the A2L 570 sensor to send a signal to the A2L 550 control board can be used. While the A2L 570 sensor is depicted as electrically and communicatively coupled to the A2L 550 control board via a wired connection, a person skilled in the art will understand that the A2L 570 sensor can be communicatively coupled to the A2L 550 control board wirelessly. In one or more modes, the A2L 570 sensor can be communicatively coupled to the A2L 550 control board by any wireless means, such as Wi-Fi or Bluetooth. Furthermore, in one or more configurations, the A2L 570 sensor may be arranged inside the indoor unit 520 to detect an A2L refrigerant leak occurring within the indoor evaporator coil 524 of the HVAC system 500. As depicted, in one or more configurations, the A2L 570 sensor may be positioned directly against the indoor evaporator coil to minimize the time it takes for the A2L 570 sensor to detect an A2L refrigerant leak. Additionally, although the A2L 570 sensor is depicted as being inside the indoor unit 520, a person skilled in the art will understand that the A2L 570 sensor may also be arranged inside the outdoor unit 530.Furthermore, while only one sensor is shown, a person skilled in the art will understand that multiple sensors can be incorporated into the HVAC system to ensure that an A2L refrigerant leak is detected and that the required safety measures are taken within the time frame stipulated by A2L safety standards. For example, a person skilled in the art will understand that the HVAC system may include two A2L sensors, with both A2L sensors located inside the indoor unit, both A2L sensors located inside the outdoor unit, or one A2L sensor located inside each of the indoor and outdoor units.Therefore, a person skilled in the art will understand that in one or more modalities, a plurality of A2L sensors may be placed within the HVAC system with one or more A2L sensors disposed within the indoor unit and / or one or more A2L sensors disposed within the outdoor unit as deemed necessary to ensure that an A2L refrigerant leak is detected and the required safety measures are taken within the time required by A2L safety standards. Furthermore, with reference to Figure 5, in one or more configurations, the A2L 550 control board may be located inside the indoor unit 520. However, a person skilled in the art will understand that, in one or more configurations, the A2L 550 control board may be located outside the indoor unit 520 and connected to or adjacent to the indoor unit 520. In addition, as discussed above, the A2L 550 control board may be electrically coupled to the indoor control board 526, the thermostat 540, and the A2L 570 sensor. In one or more configurations, the A2L 550 control board may include a power source (not shown), a first terminal block 551, a second terminal block 552, a wire relay R 553, a wire relay G 554, a wire relay W1 555, a wire relay W2 556, a wire relay Y1 557, a wire relay Y2 558, an alarm relay 559, a first sensor connect 560, a second sensor connect 561, a buzzer 562, an LED 563, a dry contact relay 564, and the first and second fan contact points 565a and 565b. The power source can be coupled to the circuit system on the A2L 550 control board so that the A2L control board can open and close at least the R 553 wire relay, the G 554 wire relay, the W1 555 wire relay, the W2 556 wire relay, the Y1 557 wire relay, the Y2 558 wire relay, the alarm relay 559, and the dry contact relay 564. In one or more modes, the thermostat 540 can be electrically coupled to the first terminal block 551, and the indoor control board 526 can be electrically coupled to the second terminal block 552. In addition, in one or more modes, any signal received by the A2L control board 550 from the thermostat 540 can be passed unchanged, through the A2L control board 550, to the indoor control board 530 via the second terminal block 552. In one or more configurations, wire relay R 553 can be electrically connected between the power supply and the wire connection R of the first terminal block 551. Therefore, when wire relay R 553 is closed, 24-volt AC power can be supplied from the A2L control board 550 to the thermostat 540 via the first terminal block 551, which switches on the thermostat 540. Furthermore, when wire relay R 553 is open, power cannot reach the thermostat, and therefore the thermostat, and indirectly the outdoor unit 530, are completely switched off. Additionally, as shown in Figure 5, in one or more configurations, the default state for wire relay R 553 is open. In one or more configurations, wire relay G 554 can be electrically placed between the power source and wire connection G of the second terminal block 552. Therefore, when wire relay G 554 is closed, 24-volt AC power can be supplied from the A2L control board 550 to the indoor control board 526 via the first terminal block 551, signaling the indoor control board 526 to turn on blower motor 523. Furthermore, when wire relay G 554 is open, no signal is sent along wire G to the indoor control board 526, and therefore blower motor 523 is turned off. Additionally, as depicted in Figure 5, in one or more configurations, the default state for wire relay G 554 is closed. In one or more configurations, the wire relay W1 555 can be electrically arranged between the power source and wire connection W1 of the second terminal block 552, and the wire relay W2 556 can be electrically arranged between the power source and wire connection W2 of the second terminal block 552. Therefore, when the wire relay W1 555 and the wire relay W2 556 are closed, 24-volt AC power can be supplied from the A2L control board 550 to the indoor control board 526 via the first terminal block 551, which signals the indoor control board 526 to operate the first and second stages of the heating system, respectively. Furthermore, when wire relay W1 555 and wire relay W2 556 are open, no signal is sent along wires W1 or W2 to the indoor control board 526, and therefore the heating system is switched off.Additionally, as depicted in Figure 5, in one or more modes, the default states for wire relay W1 555 and wire relay W2 556 must be open. In one or more configurations, wire relay Y1 557 can be electrically arranged between the power source and wire connection Y1 of the second terminal block 552, and wire relay Y2 558 can be electrically arranged between the power source and wire connection Y2 of the second terminal block 552. Therefore, when wire relay Y1 557 and wire relay Y2 558 are closed, 24-volt AC power can be supplied from control board A2L 550 to the indoor control board 526 via the first terminal block 551, which signals the indoor control board 526 to operate the first and second stages of the cooling system, respectively. Furthermore, when wire relay Y1 557 and wire relay Y2 558 are open, no signal is sent along wires Y1 or Y2 to the indoor control board 526, and therefore the cooling system shuts down.Additionally, as depicted in Figure 5, in one or more modes, the default states for wire relay Y1 557 and wire relay Y2 558 must be closed. Additionally, in one or more configurations, alarm relay 559 can be electrically arranged between the power source and an alarm (not shown), which includes, in part, buzzer 562 and LED 563. Therefore, when alarm relay 559 is closed, 24-volt AC power can be supplied to the alarm on the A2L control board 550, which turns on at least buzzer 562 and LED 563. Furthermore, when alarm relay 559 is open, no power is supplied to the alarm on the A2L control board, and it remains off. Additionally, as depicted in Figure 5, in one or more configurations, the default state for alarm relay 559 is closed. Finally, in one or more configurations, dry contact relay 564 may be electrically arranged between the power source and a fan (not shown) if the HVAC 500 system includes a fan, which is electrically coupled to the A2L 550 control board via the first and second fan contact points 565a and 565b. Therefore, when dry contact relay 564 is closed, 24-volt AC power can be supplied to the fan, turning it on. Furthermore, when dry contact relay 564 is open, no power is supplied to the fan, and it remains off. Additionally, as depicted in Figure 5, in one or more configurations, the default state for dry contact relay 564 is closed. Additionally, in one or more modes, once the system is powered on, the A2L 550 control board can be configured to open all relays except wire relay R 553, which can be configured to close in order to provide 24-volt AC power to thermostat 540 and turn on thermostat 540. Furthermore, as discussed previously, in one or more modes, the A2L 550 control board can be configured to act as a pass-through for any signal sent by the thermostat during system operation. For example, if the HVAC 500 system is required to cool the interior of a building, the thermostat can send signals along wires G and Y1 to the A2L 550 control board.The A2L 550 control board can be configured to receive these signals and, consequently, close wire relay G 554 and wire relay Y1 557 so that a 24-volt AC signal can pass to the indoor control board 526 along wire G and wire Y1. Once received, the indoor control board 526 can be configured to turn on the blower motor 523 and operate the cooling system as required by a signal on wire G and wire Y1. Furthermore, in one or more modes, the power supply can be connected to the first sensor connector 560 and the second sensor connector 561 separately. Therefore, in one or more modes, the A2L 550 control board can test one or more A2L 570 sensors separately before closing the R-wire relay 553 and switching on the thermostat 540 and the outdoor unit 530. This allows the A2L 550 control board to ensure that the 570 sensors are functioning correctly and that there are no A2L refrigerant leaks before starting the system. Although two separate sensor connectors are shown, a person skilled in the art will understand that the A2L control board may instead include a sensor signal input contact and a sensor signal output contact, and the one or more sensors may operate in signal rather than in parallel. Therefore, when the A2L 550 control board receives a signal from the A2L 570 sensor indicating an A2L refrigerant leak, the A2L 550 control board can be configured to implement the safety measures required by A2L safety standards. More specifically, in one or more modes, if a leak is detected, the A2L 550 control board can be configured to cut power to the thermostat 540 and, consequently, to the outdoor unit 530, by opening wire relay R 553. Furthermore, if a leak is detected, the A2L 550 control board can be configured to cut power to all parts of the indoor unit 520 except the blower motor 523 by opening at least wire relays W1 555 and W2 556 and closing at least wire relay G 554.Opening wire relay W1 555 and wire relay W2 556 will ensure that all heating functions are turned off, while closing wire relay G 554 will ensure that the blower motor 523 is on. In one or more modes, wire relays Y1 557 and Y2 558 may also be closed, as cutting power to the outdoor unit 530 ensures that all cooling functions are turned off, but the signal on wires Y1 and Y2 causes the indoor control board 526 to increase the speed of the blower motor 523 so that it blows more air, faster. This allows the HVAC system 500 to meet A2L safety requirements within the required time after the detection of an A2L refrigerant leak. Additionally, in one or more modes, if a leak is detected, the A2L 550 control board can close alarm relay 559 and dry contact relay 564. Closing alarm relay 559 will trigger the alarm on the A2L 550 control board, which will include, at a minimum, turning on buzzer 562 and LED 563 to provide audible and visual alerts that a leak has been detected. Furthermore, if the HVAC 500 system includes a fan, closing dry contact relay 564 will turn on the fan, which will help remove any concentration of A2L refrigerant that may have leaked into the HVAC 500 system. Furthermore, in one or more modes, if the A2L 550 control board fails, all relays return to their default state. As discussed earlier and illustrated in Figure 5, in a default state, wire relay G 554, wire relay Y1 557, wire relay Y2 558, alarm relay 559, and dry contact relay 564 may be closed, while wire relay R 553, wire relay W1 555, and wire relay W2 556 may be open. Therefore, if the A2L 550 control board fails, power to the thermostat 540, and consequently to the outdoor unit 530, will be cut off. The only signals the indoor unit 520 will receive and act upon will cause the blower motor 523 to start as fast as it can. Additionally, if the A2L 550 control board fails, the alarm will sound and the fan will turn on. With reference now to Figure 6, a flow diagram of one modality of a 600 method of installing and operating a non-communicating HVAC system using an A2L refrigerant is illustrated, as described above with respect to Figure 5, according to one or more modalities.Beginning with an HVAC system 500 in which the indoor unit 520 has been disposed of inside 511 of a building 510, the outdoor unit 530 has been disposed of outside 512 of the building 510, the indoor control board 526 has been electrically coupled to a blower motor 523 of the blower 521, and the outdoor control board 531 has been electrically coupled to the thermostat 540, method 600 may include one or more of the following: (step 610) installing the A2L control board 550 and the A2L sensor 570 in the HVAC system 500, (step 620) testing the A2L sensor 570, (step 630) starting operation of the HVAC system 500, (step 640) checking for A2L refrigerant leaks, and (step 650) taking safety measures upon detecting an A2L refrigerant leak. In step 610, an A2L 550 control board and an A2L 570 sensor can be installed in the HVAC 500 system. Installation of the A2L 550 control board and the A2L 570 sensor may include, at least, (step 611) physically attaching the A2L 570 sensor to the indoor evaporator coil 524 of the indoor unit 520, (step 612) electrically attaching the A2L 570 sensor to the A2L 550 control board, (step 613) electrically attaching the A2L 550 control board to the indoor control board 526, (step 614) electrically attaching the A2L 550 control board to the thermostat 540, and (step 615) turning on the A2L 550 control board and opening the G 554 wire relay, the Y1 557 wire relay, the Y2 558 wire relay, the alarm relay 559 and the dry contact relay 564. Ala / a / zu^o / uuoouu In one or more configurations, in step 611, the A2L 570 sensor can be placed inside the indoor unit 520 so that it is adjacent to or connected to the indoor evaporator coil 524, enabling the A2L 570 sensor to detect an A2L refrigerant leak if one occurs. Additionally, in step 612, the A2L 570 sensor can be electrically coupled to the A2L 550 control board, allowing bidirectional communication between the A2L 570 sensor and the A2L 550 control board. For example, in one or more configurations, an A2L 570 sensor can be electrically coupled to a first sensor connector 557 on the A2L 550 control board via an RS-485 bus. An expert in the field will appreciate that in other configurations, any other electrical coupling that allows bidirectional communication between the A2L 570 sensor and the A2L 550 control board can be used. In step 613, the A2L 550 control board can be electrically coupled to the indoor control board 526. In one or more configurations, wires R, C, G, W1, W2, Y1, Y2, O, and Dehum can be electrically coupled at one end to a terminal block inside the indoor control board 526 and at the other end to the second terminal block 552 of the A2L 550 control board. Furthermore, in step 614, the A2L 550 control board can be electrically coupled to the thermostat 540. In one or more configurations, wires R, C, G, W1, W2, Y1, Y2, O, and Dehum can be electrically coupled at one end to a terminal block inside the thermostat 540 and at the other end to the first terminal block 551 of the A2L 550 control board. Therefore, in one or more In these modes, the A2L 550 control board can be configured to receive control signals from the thermostat 540 and send those same control signals to the indoor control board 526.Additionally, in one or more modes, the A2L 550 control board can be configured to supply power to the thermostat 540 via the R wire to turn on the thermostat, which in turn turns on the outdoor unit 530. In one or more modes, the power supplied to the thermostat 540 by the A2L 550 control board is 24-volt AC power. In stage 615, the A2L 550 control board can be powered on, and wire relay G 554, wire relay Y1 557, wire relay Y2 558, alarm relay 559, and dry contact relay 564 can be opened. In one or more modes, when the A2L 550 control board is powered on, the relays are in their default state, which includes wire relay G 554, wire relay Y1 557, wire relay Y2 558, alarm relay 559, and dry contact relay 564 closed. Therefore, to ensure that no unnecessarily signals are provided to the indoor control board 526 to turn on the blower motor 523 and that the alarm and fan are not unnecessarily activated, in one or more modes, when the A2L control board 550 is turned on, the A2L control board opens wire relay G 554, wire relay Y1 557, wire relay Y2 558, alarm relay 559, and dry contact relay 564. Ala / a / zu^o / uuoouu In step 620, the A2L 570 sensor can be evaluated to confirm it is functioning correctly. Once electrically coupled to the A2L 550 control board in one or more modes, the A2L 570 sensor can perform an internal diagnostic check to ensure it is functioning correctly and can detect an A2L refrigerant leak. If the diagnostic check is successful, the A2L 570 sensor can communicate the successful check to the A2L 550 control board, which can then begin operating the HVAC 500 system. If the A2L 570 sensor fails the diagnostic check, it will communicate the failed check to the A2L 550 control board, which will remain in its default settings, preventing the HVAC 500 system from operating until the A2L sensor is repaired or replaced. In stage 630, the A2L 550 control board can begin operating the HVAC 500 system. To initiate operation, in one or more modes, the A2L 550 control board can close wire relay R 553. Closing wire relay R 553 allows 24-volt AC power from the A2L 550 control board to flow to thermostat 540 and then to outdoor unit 530. Once thermostat 540 is turned on, it can send signals to indoor unit 520, via the A2L 550 control board, as well as to outdoor unit 530, and the HVAC 500 system can become fully operational. In step 640, while the HVAC system is operating in one or more modes, the A2L 570 sensor can check for A2L refrigerant leaks. The A2L 570 sensor can continuously check for A2L refrigerant leaks while the HVAC 500 system is running. If a check is negative for an A2L refrigerant leak, the A2L 570 sensor repeats step 640. However, if the A2L 570 sensor detects an A2L leak, it reports the leak to the A2L control board, and the HVAC system proceeds to step 650. In stage 650, the HVAC 500 system, via the A2L 550 control board, can implement safety measures to eliminate the threat of a detected A2L refrigerant leak. Specifically, the HVAC 500 system (stage 652) can open wire relay R 553, (stage 653) close wire relay G 554, (stage 654) open wire relays W1 555 and W2 556, (stage 655) close wire relays Y1 557 and Y2 558, (stage 656) close dry contact relay 564, and (stage 657) close alarm relay 559. In step 652, opening wire relay R 553 prevents the A2L control board 550 from distributing 24-volt AC power to thermostat 540. Removing 24-volt AC power from thermostat 540, in turn, removes power from the outdoor unit 530, which is configured to receive 24-volt AC power signals directly from the thermostat. Additionally, in step 653, closing wire relay G 554 causes the A2L control board 550 to send 24-volt AC power along wire G to the indoor control board. 526, which starts the blower motor 523 when it receives the signal along wire G. Additionally, in stage 654, opening wire relay W1 555 and wire relay W2 556 ensures that no signal is sent to the indoor control board 526 and therefore heating operations are not performed while the system experiences a coolant leak. Additionally, in stage 655, closing wire relay Y1 557 and wire relay Y2 558 causes the A2L control board 550 to send 24-volt AC power along wires Y1 and Y2 to the indoor control board 526. The indoor control board 526 interprets the signals along wires Y1 and Y2 to request first- and second-stage cooling operations, but because the compressor in the outdoor unit 530 is off, the only effect is that the indoor control board 526 runs the motor fan 532 at its highest speed. Furthermore, in step 656, closing the dry contact relay 564 causes the 24-volt AC power from the A2L 550 control board to turn on an attached fan if the HVAC 500 system includes a fan. Additionally, in step 657, closing the alarm relay 559 causes the 24-volt AC power from the A2L 550 control board to activate the alarm, which includes, at a minimum, turning on visual and audible alarms in the form of buzzer 562 and LED 563. Furthermore, although listed as separate steps, a person skilled in the art will appreciate that in one or more of the procedures, steps 652–657 can occur in any order, or in other procedures, steps 652–657 can occur simultaneously. Additionally, a person skilled in the art will appreciate that all steps 652–657 can be completed within the time required after the detection of an A2L refrigerant leak, as required by A2L safety standards. Therefore, in one or more modes, in response to a communication from the A2L sensor 570 that an A2L refrigerant leak has been detected, the A2L control board 550 can shut down the outdoor unit 530, turn on a fan if the HVAC system 500 has one, turn on the visual and audible alarms that an A2L refrigerant has been detected, and ensure that the only signals the indoor unit 520 receives and acts upon will cause the blower motor 523 to start as quickly as possible. Although Method 600 is described with respect to an HVAC 500 system that includes a single A2L 570 sensor, a person skilled in the art will understand that any number of sensors can be used in the system and the method may include electrically coupling the additional sensors to the control board, evaluating the additional sensors, and communicating with the additional sensors as the additional sensors check for A2L refrigerant leaks. Figure 7 shows a communicating HVAC system using an A2L refrigerant, according to one or more modes. In one or more modes, an A2L system can be used. HVAC 700 to distribute cooled or heated air throughout a building 710 to adjust the ambient air temperature inside 711 of the building 710. The HVAC system may include an indoor unit 720, an outdoor unit 730, a thermostat 740, an A2L control board 750, an A2L sensor 770, an outdoor relay 780 and a high pressure switch 790. Generally, in one or more configurations, the indoor unit 720 can be seamlessly coupled to the outdoor unit 730 so that an A2L refrigerant can flow between the indoor unit 720 and the outdoor unit 730 to cool or heat the air inside the indoor unit 720. Furthermore, in one or more configurations, both the indoor unit 720 and the outdoor unit 730 can be communicatively coupled to each other via an RS485 communication system. Additionally, in one or more configurations, the A2L 750 control board can be directly electrically and / or communicatively coupled to the indoor unit 720 and the thermostat 740, and also indirectly electrically coupled to the outdoor unit 730 via the outdoor relay 780 and the high-pressure switch 790.The thermostat 740 can be electrically coupled to the A2L 750 control board so that it can send communications and signals to the indoor unit 720 via the A2L 750 control board. Therefore, the A2L 750 control board can be configured to directly affect the operation of the indoor unit 720 through these communications and signals, and can also be configured to directly affect the operation of the outdoor unit 730 via the outdoor relay 780 and the high-pressure switch 790. Furthermore, the A2L 770 sensor can be physically installed inside the indoor unit 720 and electrically coupled to the A2L 750 control board. The A2L 770 sensor can be configured to send signals to the A2L 750 control board when an A2L refrigerant leak is detected. While the A2L 750 control board is depicted as electrically and communicatively coupled to the 720 indoor unit, the 740 thermostat, and the A2L 770 sensor via a wired connection, those skilled in the art will understand that the 720 indoor unit, the 740 thermostat, and the A2L 770 sensor can be communicatively coupled to the A2L 750 control board wirelessly. In one or more modes, the 720 indoor unit, the 740 thermostat, and the A2L 770 sensor can be communicatively coupled to the A2L 750 control board by any wireless means, such as Wi-Fi or Bluetooth. In one or more configurations, the indoor unit 720 can be located inside 711 of building 710. The indoor unit 720 can be configured to distribute either cool or warm air to the rooms inside 711 of building 710. The indoor unit 720 can be any type of HVAC system that includes a blower 721 and a heat exchanger 727 having an indoor evaporator coil 724. Therefore, in one or more configurations, the indoor unit 720 can be either a furnace or an air handler, since both types of systems include at least a blower and an indoor evaporator coil. In addition, the evaporator coil 724 can be placed next to the blower 721, so that when the blower 721 blows air into the indoor unit 720, the air is expelled through the evaporator coil 724. Furthermore, in one or more configurations, the blower 721 may include an extractor 722 and a blower motor 723. By way of example, in one or more configurations, the blower motor 723 may be a constant torque motor, while in other configurations, the blower motor 723 may be a permanent split capacitor (PSC) motor. The blower motor 723 may be mechanically coupled to the extractor 722 so that when the blower motor 723 is switched on, the extractor 722 is configured to rotate and cause airflow out of the blower 721 and through the indoor evaporator coil 724. The indoor evaporator coil 724 may be configured to receive the A2L refrigerant on the inside of the coil, while the air from the blower 721 is blown across the outside of the coil, allowing heat to be exchanged between the A2L refrigerant and the air, or vice versa.The A2L refrigerant, after cooling or heating the air, can return to the outdoor unit 730, where it will undergo the reverse heat exchange process before returning to the indoor evaporator coil 724. In addition, the indoor unit 720 is configured to distribute the air blown from the blower 721 and through the indoor evaporator coil 724 to the rooms inside 711 of the building 710 by means of the force of the blower 721. The indoor unit 720 may also include a transformer 725 and an indoor control board 726. The transformer 725 can be directly electrically coupled and configured to provide 24 volt AC power to the indoor control board 726. In addition, the indoor control board 726 can be electrically coupled to at least the A2L control board 750 and the blower motor 723. Furthermore, the outdoor unit 730 can be located outside 712 of building 710 and configured to use the outside environment to reheat or cool the A2L refrigerant after it has passed through the indoor evaporator coil 724. The outdoor unit 730 may include, but is not limited to, a heat pump or an air conditioner. Whether the outdoor unit 730 is a heat pump or an air conditioner, it may include a compressor (not shown), an outdoor coil (not shown), and an outdoor control board 731. The outdoor unit 730 can be configured to communicate with the indoor unit 720 via the RS-485 communication system between the indoor control board 726 and the outdoor control board 731. Additionally, the outdoor control board 731 can be electrically coupled to the A2L control board 750 as discussed below. With reference to Figure 7, the A2L 770 sensor can be configured in one or more modes to detect an A2L refrigerant leak and send a signal to report it. In one or more modes, the A2L 770 sensor can be configured to detect an A2L refrigerant leak using one of several methods, including at least detecting a quantity or concentration of A2L refrigerant in the air that exceeds a leak threshold. The A2L 770 sensor can be electrically coupled and communicate with the A2L 750 control board. In one or more modes, the A2L 770 sensor can be electrically coupled to the A2L 750 control board by means of a 760 sensor connector. The A2L 770 sensor can be configured to communicate to the A2L 750 control board that the A2L 770 sensor is connected to the system and functioning correctly.Furthermore, when the A2L 770 sensor detects an A2L refrigerant leak, it can report the leak to the A2L 750 control board, which can be configured to receive the signal and perform the safety measures required by A2L safety standards. In one or more configurations, the A2L 770 sensor and the A2L 750 control board can be electrically coupled via an RS-485 bus; however, a person skilled in the art will understand that any type of electrical connection that allows the A2L 770 sensor to send a signal to the A2L 750 control board can be used. Furthermore, in one or more configurations, the A2L 770 sensor can be arranged inside the indoor unit 720 to detect an A2L refrigerant leak occurring within the indoor evaporator coil 724 of the HVAC system 700. As depicted, in one or more configurations, the A2L 770 sensor can be positioned directly against the indoor evaporator coil to minimize the time it takes for the A2L 770 sensor to detect an A2L refrigerant leak. Additionally, although the A2L 770 sensor is depicted as being inside the indoor unit 720, a person skilled in the art will understand that the A2L 770 sensor can also be arranged inside the outdoor unit 730.Furthermore, while only one sensor is shown, a person skilled in the art will understand that multiple sensors can be incorporated into the HVAC system to ensure that an A2L refrigerant leak is detected and that the required safety measures are taken within the time frame stipulated by A2L safety standards. For example, a person skilled in the art will understand that the HVAC system may include two A2L sensors, with both A2L sensors located inside the indoor unit, both A2L sensors located inside the outdoor unit, or one A2L sensor located inside each of the indoor and outdoor units.Therefore, a person skilled in the art will understand that in one or more modalities, a plurality of A2L sensors may be placed within the HVAC system with one or more A2L sensors disposed within the indoor unit and / or one or more A2L sensors disposed within the outdoor unit as deemed necessary to ensure that an A2L refrigerant leak is detected and the required safety measures are taken within the time required by A2L safety standards. Furthermore, with reference to Figure 7, in one or more configurations, the A2L 750 control board may be located inside the indoor unit 720. However, a person skilled in the art will understand that, in one or more configurations, the A2L 750 control board may be located outside the indoor unit 720 and connected to or adjacent to the indoor unit 720. Additionally, besides being electrically coupled to the indoor control board 726, the thermostat 740, and the A2L 770 sensor, as explained above, the A2L 750 control board may be electrically coupled to the outdoor control board 731 by means of the outdoor relay 780 and the high-pressure switch 790. In one or more configurations, the outdoor relay 780 and the high-pressure switch 790 may be electrically coupled in series. between the A2L 750 control board and the 731 external control board.In one or more configurations, the outdoor relay 780 can be electrically coupled directly to the A2L 750 control board so that the outdoor relay 780 is configured to open upon receiving a 24-volt AC power signal from the A2L 750 control board. Additionally, in one or more configurations, the high-pressure switch 790 is electrically coupled to the outdoor control board 731 so that when the high-pressure switch 790 opens, the outdoor unit 730 shuts down completely. Furthermore, in one or more configurations, the opening of the outdoor relay 780 causes the high-pressure switch 790 to open, resulting in the outdoor unit 730 shutting down completely. In one or more configurations, the A2L 750 control board may include a power supply (not shown), a first terminal block 751, a second terminal block 752, a wire relay R 753, a wire relay G 754, a wire relay W1 755, a wire relay W2 756, a wire relay Y1 757, a wire relay Y2 758, an alarm relay 759, a first sensor connector 760, a second sensor connector 761, a buzzer 762, an LED 763, a dry contact relay 764, the first and second fan contact points 765a and 765b, and an outdoor unit relay 766. The power supply may be coupled to the circuitry on the A2L 750 control board so that the A2L control board can open and close, minus, cable relay R 753, cable relay G 754, cable relay W1 755, cable relay W2 756, cable relay Y1 757, cable relay Y2 758, alarm relay 759, dry contact relay 764 and outdoor unit relay 766. In one or more modes, the thermostat 740 can be electrically coupled to the first terminal block 751, and the indoor control board 726 can be electrically coupled to the second terminal block 752. In addition, in one or more modes, any signal received by the A2L 750 control board from the thermostat 740 can be passed unchanged, through the A2L 750 control board, to the indoor control board 730 via the second terminal block 752. In one or more configurations, wire relay R 753 can be electrically placed between the power source and the wire connection R of the first terminal block 751. Therefore, when wire relay R 753 is closed, 24-volt AC power can be supplied from the A2L control board 750 to the thermostat 740 through the first terminal block 751, which turns on the thermostat 740. Furthermore, when wire relay R 753 is open, power cannot reach the thermostat, and therefore the thermostat turns off completely. Additionally, as depicted in Figure 7, in one or more configurations, the default state for wire relay R 753 is open. In one or more configurations, wire relay G 754 can be electrically placed between the power supply and the wire connection G of the second terminal block 752. Therefore, when wire relay G 754 is closed, 24-volt AC power can be supplied from the A2L control board 750 to the indoor control board 726 via the first terminal block 751, signaling the indoor control board 726 to turn on blower motor 723. Furthermore, when wire relay G 754 is open, no signal is sent along wire G to the indoor control board 726, and therefore blower motor 723 is turned off. Additionally, as depicted in Figure 7, in one or more configurations, the default state for wire relay G 754 is closed. In one or more configurations, the wire relay W1 755 can be electrically arranged between the power source and wire connection W1 of the second terminal block 752, and the wire relay W2 756 can be electrically arranged between the power source and wire connection W2 of the second terminal block 752. Therefore, when the wire relay W1 755 and the wire relay W2 756 are closed, 24-volt AC power can be supplied from the control board A2L 750 to the indoor control board 726 via the first terminal block 751, which signals the indoor control board 726 to operate the first and second stages of the heating system, respectively. Furthermore, when wire relay W1 755 and wire relay W2 756 are open, no signal is sent along wires W1 or W2 to the indoor control board 726, and therefore the heating system is switched off.Additionally, as depicted in Figure 7, in one or more modes, the default states for wire relay W1 755 and wire relay W2 756 must be open. In one or more configurations, wire relay Y1 757 can be electrically arranged between the power source and wire connection Y1 of the second terminal block 752, and wire relay Y2 758 can be electrically arranged between the power source and wire connection Y2 of the second terminal block 752. Therefore, when wire relay Y1 757 and wire relay Y2 758 are closed, 24-volt AC power can be supplied from the A2L control board 750 to the indoor control board 726 via the first terminal block 751, which signals the indoor control board 726 to operate the first and second stages of the cooling system, respectively. Furthermore, when wire relay Y1 757 and wire relay Y2 758 are open, no signal is sent along wires Y1 or Y2 to the indoor control board 726 and therefore the cooling system is turned off.Additionally, as depicted in Figure 7, in one or more modes, the default states for wire relay Y1 757 and wire relay Y2 758 must be closed. Furthermore, in one or more configurations, alarm relay 759 can be electrically arranged between the power source and an alarm (not shown), which includes, in part, buzzer 762 and LED 763. Therefore, when alarm relay 759 is closed, 24-volt AC power can be supplied to the alarm on the A2L 750 control board, which turns on at least buzzer 762 and LED 763. Additionally, when alarm relay 759 is open, no power is supplied to the alarm on the A2L control board, and it remains off. Furthermore, as depicted in Figure 7, in one or more configurations, the default state for alarm relay 759 is closed. In addition, in one or more configurations, dry contact relay 764 may be electrically arranged between the power source and a fan (not shown) if the HVAC 700 system includes a fan, which is electrically coupled to the A2L 750 control board via the first and second fan contact points 765a and 765b. Therefore, when dry contact relay 764 is closed, 24-volt AC power can be supplied to the fan, turning it on. Furthermore, when dry contact relay 764 is open, no power is supplied to the fan, and it remains off. Additionally, as depicted in Figure 7, in one or more configurations, the default state for dry contact relay 764 is closed. Additionally, in one or more configurations, the outdoor unit relay 766 can be electrically connected between the power supply and a contact point on the outdoor unit 767. In one or more configurations, the outdoor unit relay 780 can be electrically coupled to the A2L 750 control board via the outdoor unit contact point 767. Therefore, when the outdoor unit relay 766 is closed, 24-volt AC power can be supplied to the outdoor unit relay 780, causing it to open, thereby opening the high-pressure switch 790 and shutting down the outdoor unit 730. Furthermore, when the outdoor unit relay 766 is open, power is not supplied to the outdoor unit relay 780, and the outdoor unit 730 continues to operate. Additionally, as shown in Figure 7, in one or more configurations, the default state for the outdoor unit relay 766 is closed. Additionally, in one or more modes, once the system is powered on, the A2L 750 control board can be configured to open all relays except wire relay R 753, which can be configured to close in order to provide 24-volt AC power to thermostat 740 and turn on thermostat 740. Furthermore, as discussed previously, in one or more modes, the A2L 750 control board can be configured to act as a pass-through for any signal sent by the thermostat during system operation. For example, if the HVAC 700 system is required to cool the interior of a building, the thermostat can send signals along wires G and Y1 to the A2L 750 control board.The A2L 750 control board can be configured to receive these signals and, consequently, close wire relay G 754 and wire relay Y1 757 so that a 24-volt AC signal can pass to the indoor control board 726 along wire G and wire Y1. Once received, the indoor control board 726 can be configured to turn on the blower motor 723 and operate the cooling system as required by a signal on wire G and wire Y1. Furthermore, in one or more configurations, the power supply can be connected to the first sensor connector 760 and the second sensor connector 761 separately. Therefore, in one or more configurations, the A2L 750 control board can test one or more A2L 770 sensors separately before closing the R-wire relay 753 and turning on the thermostat 740. This allows the A2L 750 control board to ensure that the 770 sensors are functioning correctly and that there are no A2L refrigerant leaks before starting the system. Although two separate sensor connectors are shown, a person skilled in the art will understand that the A2L control board may instead include a sensor signal input contact and a sensor signal output contact, and the one or more sensors may operate in series instead of parallel. Therefore, when the A2L 750 control board receives a signal from the A2L 770 sensor indicating an A2L refrigerant leak, the A2L 750 control board can be configured to implement the safety measures required by A2L safety standards. More specifically, in one or more modes, if a leak is detected, the A2L 750 control board can be configured to cut power to the thermostat 740 by opening wire relay R 753 and to shut down the outdoor unit 730 by closing the outdoor unit relay 766. Furthermore, if a leak is detected, the A2L 750 control board can be configured to cut power to all parts of the indoor unit 720 except the blower motor 723 by opening at least wire relays W1 755 and W2 756 and closing at least wire relay G 754.Opening wire relays W1 755 and W2 756 will ensure that all heating functions are switched off, while closing wire relay G 754 will ensure that the blower motor 723 is switched on. In one or more modes, wire relays Y1 757 and Y2 758 may also be closed, as cutting power to the outdoor unit 730 ensures that all cooling functions are switched off, but the signal on wires Y1 and Y2 may cause the indoor control board 726 to increase the speed of the blower motor 723 so that it blows more air, faster. Additionally, closing the outdoor unit relay 766 in response to the detection of an A2L refrigerant leak causes power to be applied directly to the outdoor relay 780. Applying power directly to the outdoor relay 780 causes it to open. Ala / a / zu^o / uuoouu Furthermore, the opening of outdoor relay 780 is configured to open high-pressure switch 790. Additionally, outdoor unit 730 is configured to shut down completely if high-pressure switch 790 opens. Therefore, the closing of outdoor unit relay 766 is configured to completely shut down outdoor unit 730. This allows the HVAC 700 system to meet A2L safety requirements within the required time after the detection of an A2L refrigerant leak. While Figure 7 depicts one or more embodiments of the present invention that utilize an outdoor relay 780 and a high-pressure switch 790 to shut down the outdoor unit in the event of an A2L refrigerant leak, a person skilled in the art will understand that any means of shutting down the outdoor unit compressor will function to adequately meet the A2L safety requirements. By way of example, in one or more embodiments, the HVAC system may include an A2L control board that is electrically coupled to a contactor, wherein the contactor is configured to contact the outdoor control board so that the outdoor unit shuts down in the event of an A2L refrigerant leak.In addition, in other configurations, the A2L control board can be communicatively coupled to the outdoor control board via RS-485 system communication, enabling the A2L control board to instruct the outdoor control board to shut down the outdoor unit if an A2L leak is detected. Furthermore, in one or more configurations, the A2L control board can be electrically coupled to a relay. This relay is positioned between the outdoor control board and the outdoor unit's compressor, so that when the relay opens, power from the outdoor control board is cut off to the compressor, causing it to shut down. Furthermore, while in one or more modes the A2L control board uses a 24-volt AC signal to communicate with the outdoor relay to shut down the outdoor unit, a person skilled in the art will understand that, in one or more modes, the A2L control board can send digital signals to the outdoor relay. A person skilled in the art will understand that these digital signals can also be used with a contactor or any other relay connected to the outdoor control board to shut down the outdoor unit. Additionally, in one or more modes, the A2L control board can be wirelessly connected to the outdoor control board so that wireless signals can be used to shut down the outdoor unit. Additionally, in one or more modes, if a leak is detected, the A2L 750 control board can close alarm relay 759 and dry contact relay 764. Closing alarm relay 759 will trigger the alarm on the A2L 750 control board, which will include, at a minimum, turning on buzzer 762 and LED 763 to provide audible and visual alerts that a leak has been detected. Furthermore, if the HVAC 700 system includes a fan, closing dry contact relay 764 will turn on the fan, which will help remove any concentration of A2L refrigerant that may have leaked into the HVAC 700 system. Furthermore, in one or more modes, if the A2L 750 control board fails, all relays return to their default state. As discussed earlier and illustrated in Figure 7, in a default state, wire relay G 754, wire relay Y1 757, wire relay Y2 758, alarm relay 759, dry contact relay 764, and outdoor unit relay 766 may all be closed, while wire relay R 753, wire relay W1 755, and wire relay W2 756 may all be open. Therefore, if the A2L 750 control board fails, the outdoor unit 730 will shut down via the open high-pressure switch, and the only signals received and acted upon by the indoor unit 720 will cause the blower motor 723 to start as fast as it can. Additionally, if the A2L 750 control board fails, the alarm will sound and the fan will turn on. With reference now to Figure 8, a flow diagram of one modality of an 800 method of installation and operation of a communicating HVAC system using an A2L refrigerant is illustrated, as described above with respect to Figure 7, according to one or more modalities.Starting with an HVAC 700 system in which the indoor unit 720 has been disposed of inside 711 of a building 710, the outdoor unit 730 has been disposed of outside 712 of building 710, the indoor control board 726 has been electrically coupled to the transformer 725 and a blower motor 723 of the blower 721, and the outdoor control board 731 has been communicatively coupled to the indoor control board 726, method 800 may include one or more of the following: (step 810) installing the A2L 750 control board and the A2L 770 sensor in the HVAC 700 system, (step 820) testing the A2L 770 sensor, (step 830) starting operation of the HVAC 700 system, (step 840) checking for leaks of A2L refrigerant, and (stage 850) taking safety measures upon detecting an A2L refrigerant leak. In step 810, an A2L 750 control board and an A2L 770 sensor can be installed in the HVAC 700 system. Installation of the A2L 750 control board and the A2L 770 sensor may include, at least, (step 811) physically attaching the A2L 770 sensor to the indoor evaporator coil 724 of the indoor unit 720, (step 812) electrically attaching the A2L 770 sensor to the A2L 750 control board, (step 813) electrically attaching the A2L 750 control board to the indoor control board 726, (step 814) electrically attaching the A2L 750 control board to the outdoor control board 731, (step 815) electrically attaching the control board of A2L 750 to thermostat 740, and (step 816) turn on the A2L 750 control board and open wire relay G 754, wire relay Y1 757, wire relay Y2 758, alarm relay 759, dry contact relay 764, and outdoor unit relay 766. In one or more configurations, in step 811, the A2L 770 sensor can be placed inside the indoor unit 720 so that it is adjacent to or connected to the indoor evaporator coil 724, enabling the A2L 770 sensor to detect an A2L refrigerant leak if one occurs. Furthermore, in step 812, the A2L 770 sensor can be electrically coupled to the A2L 750 control board, allowing bidirectional communication between the A2L 770 sensor and the A2L 750 control board. For example, in one or more configurations, an A2L 770 sensor can be electrically coupled to a first sensor connector 757 on the A2L 750 control board via an RS-485 bus. An expert in the field will appreciate that in other configurations, any other electrical coupling that allows bidirectional communication between the A2L 770 sensor and the A2L 750 control board can be used. In step 813, the A2L 750 control board can be electrically coupled to the indoor control board 726. In one or more configurations, wires R, C, G, W1, W2, Y1, Y2, O, and Dehum can be electrically coupled at one end to a terminal block inside the indoor control board 726 and at the other end to the second terminal block 752 of the A2L 750 control board. Furthermore, in step 815, the A2L 750 control board can be electrically coupled to the thermostat 740. In one or more configurations, wires R, C, G, W1, W2, Y1, Y2, O, and Dehum can be electrically coupled at one end to a terminal block inside the thermostat 740 and at the other end to the first terminal block 751 of the A2L 750 control board. Therefore, in one or more In these modes, the A2L 750 control board can be configured to receive control signals from the thermostat 740 and send those same control signals to the indoor control board 726.Additionally, in one or more modes, the A2L 750 control board can be configured to supply power to the 740 thermostat via the R wire to turn on the 740 thermostat. In one or more modes, the power supplied to the 740 thermostat by the A2L 750 control board is 24-volt AC power. In step 814, the A2L 750 control board can be electrically coupled to the outdoor control board 731. In one or more configurations, the high-pressure switch 790 can be electrically coupled to the outdoor control board 731 so that when the high-pressure switch 790 opens, the outdoor control board 731 switches off. Additionally, the outdoor relay 780 can be electrically coupled to the high-pressure switch 790 so that when the outdoor relay opens, the high-pressure switch opens. Furthermore, the outdoor relay 780 can be electrically coupled to a contact point on the outdoor unit 767 of the A2L 750 control board by means of a cable capable of carrying 24-volt AC power.Therefore, by way of example, if the outdoor unit relay 766 of the A2L 750 control board closes, a 24-volt AC signal will be provided to the outdoor relay 780 causing the outdoor relay 780 to open, which causes the high-pressure switch 790 to open, which turns off the outdoor unit 730, which includes the outdoor control board 731. In stage 816, the A2L 750 control board can be powered on, and the G 754 wire relay, Y1 757 wire relay, Y2 758 wire relay, alarm relay 759, dry contact relay 764, and outdoor unit relay 766 can be opened. In one or more modes, when the A2L 750 control board is powered on, the relays are in their default state, which includes the G 754 wire relay, Y1 757 wire relay, Y2 758 wire relay, alarm relay 759, dry contact relay 764, and outdoor unit relay 766 closed.Therefore, to ensure that signals are not unnecessarily provided to the indoor control board 726 to turn on the blower motor 723, the outdoor unit 730 is not unnecessarily shut down by the high-pressure switch, and the alarm and fan are not unnecessarily activated, in one or more modes, when the A2L control board 750 is turned on, the A2L control board opens wire relay G 754, wire relay Y1 757, wire relay Y2 758, alarm relay 759, dry contact relay 764, and the outdoor unit relay 766. In step 820, the A2L 770 sensor can be evaluated to confirm it is functioning correctly. Once electrically coupled to the A2L 750 control board in one or more modes, the A2L 770 sensor can perform an internal diagnostic check to ensure it is functioning correctly and can detect an A2L refrigerant leak. If the diagnostic check is successful, the A2L 770 sensor can communicate the successful check to the A2L 750 control board, which can then begin operating the HVAC 700 system. If the A2L 770 sensor fails the diagnostic check, it will communicate the failed check to the A2L 750 control board, which will remain in its default settings, preventing the HVAC 700 system from operating until the A2L sensor is repaired or replaced. In stage 830, the A2L 750 control board can begin operating the HVAC 700 system. To initiate operation, in one or more modes, the A2L 750 control board can close wire relay R 753. Closing wire relay R 753 allows 24-volt AC power from the A2L 750 control board to flow to thermostat 740. Once thermostat 740 is turned on, it can send signals to the indoor unit 720 via the A2L 750 control board, and the HVAC 700 system can become fully operational. In step 840, while the HVAC system is operating in one or more modes, the A2L 770 sensor can check for A2L refrigerant leaks. The A2L 770 sensor can continuously check for A2L refrigerant leaks while the HVAC 700 system is operating, so if a check is negative for an A2L refrigerant leak, the A2L 770 sensor repeats step 840. However, if the A2L 770 sensor detects an A2L leak, then the A2L 770 sensor reports the A2L refrigerant leak to the A2L control board, and the HVAC system continues to step 850. In step 850, the HVAC 700 system, via the A2L 750 control board, can implement safety measures to eliminate the threat of a detected A2L refrigerant leak. Specifically, the HVAC 700 system can (step 852) open wire relay R 753, (step 853) close wire relay G 754, (step 854) open wire relays W1 755 and W2 756, (step 855) close wire relays Y1 757 and Y2 758, (step 856) close dry contact relay 764, (step 857) close alarm relay 759, and (step 858) close outdoor unit relay 766. In step 852, opening wire relay R 753 prevents the A2L control board 750 from distributing 24-volt AC power to thermostat 740. Removing 24-volt AC power from thermostat 740 ensures that only signals passing from the A2L control board 750 can reach the indoor control board 726, and therefore, safety measures can be implemented by the HVAC system 700. Additionally, in step 853, closing wire relay G 754 causes the A2L control board 750 to send 24-volt AC power along wire G to the indoor control board 726, which starts the blower motor 723 when it receives the signal along wire G. Furthermore, in step 854, opening wire relays W1 755 and W2 756 ensures that no signal is sent to the internal control board 726 and therefore heating operations are not performed while the system experiences a coolant leak.Additionally, in stage 855, closing wire relay Y1 757 and wire relay Y2 758 causes the A2L control board 750 to send 24-volt AC power along wires Y1 and Y2 to the indoor control board 726. The indoor control board 726 interprets the signals along wires Y1 and Y2 to request first- and second-stage cooling operations, but because the compressor in the outdoor unit 730 is also shutting down in this stage as discussed later, the only effect is that the indoor control board 726 runs the blower motor 732 at its highest level. Additionally, in step 858, closing the outdoor unit relay 766 causes a 24-volt AC signal to travel to the outdoor relay 780, which causes the outdoor relay 780 to open, which causes the high-pressure switch 790 to open, which causes the outdoor unit 730 to shut down completely. Furthermore, in step 856, closing the dry contact relay 764 causes the 24-volt AC power from the A2L 750 control board to turn on an attached fan if the HVAC 700 system includes one. Additionally, in step 857, closing the alarm relay 759 causes the 24-volt AC power from the A2L 750 control board to activate the alarm, which includes, at a minimum, turning on visual and audible alarms in the form of buzzer 762 and LED 763. Ala / a / zu^o / uuoouu Furthermore, although listed as separate steps, a person skilled in the art will appreciate that in one or more of the procedures, steps 852–858 can occur in any order, or in other procedures, steps 852–858 can occur simultaneously. Additionally, a person skilled in the art will appreciate that all steps 852–858 can be completed within the time required after the detection of an A2L refrigerant leak, as required by A2L safety standards. Therefore, in one or more modes, in response to a communication from the A2L 770 sensor that an A2L refrigerant leak has been detected, the A2L 750 control board can shut down the outdoor unit 730, turn on a fan if the HVAC system 700 has one, turn on the visual and audible alarms that an A2L refrigerant has been detected, and ensure that the only signals the indoor unit 720 receives and acts upon will cause the blower motor 723 to start as quickly as possible. Although Method 800 is described with respect to an HVAC 700 system that includes a single A2L 770 sensor, a person skilled in the art will understand that any number of sensors can be used in the system and the method may include electrically coupling the additional sensors to the control board, evaluating the additional sensors, and communicating with the additional sensors as the additional sensors check for A2L refrigerant leaks. With reference to Figure 9, an illustrative configuration of A2L sensors for use in HVAC systems using an A2L refrigerant is shown, according to one or more of the following configurations. As mentioned previously, while any ASHRAE Standard 34 refrigerant classified as A2L can be used, in one or more configurations, the A2L refrigerant may be R-32. Furthermore, in one or more configurations, all references to A2L may specifically relate to R-32. For example, with reference to Figures 9 and 10, an A2L refrigerant may be R-32, an A2L sensor may be an R-32 sensor configured to detect quantities of R-32 refrigerant in order to detect an R-32 leak, and an A2L control board may be a control board configured to work with R-32 sensors to implement safety measures if an R-32 leak is detected. In one or more configurations, an HVAC 900 system may include, in part, an A2L 950 control board and one or more A2L 970a, 970b, or 970c sensors. Furthermore, as discussed earlier with respect to Figures 1, 3, 5, and 7, the A2L 970a, 970b, and 970c sensors may be electrically coupled to the A2L 950 control board, so that the A2L 970a, 970b, and 970c sensors can communicate an A2L refrigerant leak to the A2L 950 control board if one is detected. Furthermore, in one or more modes, a 4-wire RS-485 harness can be used to connect at least the first A2L 970a sensor to a first A2L 957 sensor connector on the A2L 950 control board. In addition, although an RS-485 connection can be used, a person skilled in the art will understand that any method of communicative and electrical coupling of the A2L sensors to the A2L control board can be used.Additionally, in one or more modes, a feedback cable can be used to electrically couple a final A2L 970c sensor to a second A2L 958 sensor connector on the A2L 950 control board. While each A2L 970a, 970b, 970c sensor and the A2L 950 control board are depicted as electrically and communicatively coupled to each other via a wired connection, a person skilled in the art will understand that each A2L 970a, 970b, 970c sensor and the A2L 950 control board can simply be coupled wirelessly. In one or more modes, each A2L 970a, 970b, 970c sensor and the A2L 950 control board can be coupled wirelessly using any wireless means, such as Wi-Fi or Bluetooth. In one or more configurations, each of the A2L sensors 970a, 970b, and 970c may include sensing components 971, a bus connect input 972, a bus connect output 973, a sensor relay 974, and a sensor feedback port 975. The sensing components 971 may be configured to detect an A2L gas in the air and report the detected level. Additionally, the sensing components 971 may be configured to perform internal diagnostic checks to ensure that the sensor is still operational. Furthermore, the input of bus connector 972 and the output of bus connector 973 can be physical connectors through which the sensor can be communicatively coupled to another sensor or to the A2L 950 control board. For example, on the first sensor 970a, the input of bus connector 972 can be located where a 4-wire RS-485 harness is connected to the first sensor of A2L 970a, so that the first sensor of A2L 970a is electrically coupled to the A2L 950 control board. Similarly, for example, a bus connector output of 973 on the first sensor of A2L 970a can be located where another 4-wire RS-485 harness is connected to the first sensor of A2L 970a, so that the first sensor of A2L 970a is electrically coupled to the second sensor of A2L 970b. Additionally, in one or more modes, each A2L sensor may include a sensor relay 974. The sensor relay 974 may be electrically arranged between the input of bus connector 972 and the output of bus connector 973 such that when the sensor relay 974 is open, power cannot flow from the input of bus connector 972 to the output of bus connector 973. Therefore, when the sensor relay 974 is closed, power can flow from the input of bus connector 972 to the output of bus connector 973 and then to whatever is electrically coupled to the output of bus connector 973. In one or more modes, the default position of the sensor relay 974 may be open. Furthermore, in one or more modes, the sensor relay 974 may be configured to open if the sensor fails a diagnostic check.Therefore, in one or more modes, the A2L 950 control board can know that a sensor has failed by means of a loss of signal from the feedback wire coupled to a last A2L 970c sensor, and then the A2L control board can respond by shutting down the functionality of the HVAC 900 system. Additionally, in one or more configurations, each A2L sensor may include a sensor feedback port 975. In one or more configurations, the sensor feedback port 975 may be used to send sensor feedback via a feedback cable. More specifically, in one or more configurations, the signal, which may be analog or digital and wired or wireless, sent back to the A2L 950 control board through the sensor feedback port 975 may indicate that all sensors in the network have successfully completed their internal checks, are functioning correctly, and there are no more sensors in the chain. The sensor feedback port 975 may be arranged on the sensor such that the sensor relay 974 is electrically positioned between the sensor feedback port 975 and the bus connector input 972.Therefore, when sensor relay 974 is open, power cannot travel from bus connector input 972 to sensor feedback port 975. Furthermore, when sensor relay 974 is closed, power can travel from bus connector input 972 to sensor feedback port 975 and then to whatever is electrically connected to sensor feedback port 975. In one or more configurations, as shown in Figure 9, the first A2L 970a sensor, the second A2L 970b sensor, and the last A2L 970c sensor can be connected in series and electrically coupled to the A2L 950 control board. For example, the A2L 950 control board can be electrically coupled directly to the first A2L sensor by means of a 4-wire RS-485 harness connected between the first sensor connector 957 and the bus connector input 972 of the first A2L 970a sensor. Furthermore, the first A2L 970a sensor can be directly coupled to the second A2L 970b sensor by means of a 4-wire RS-485 harness coupled between the output of bus connector 973 of the first A2L 970a sensor and the input of bus connector 972 of the second A2L 970b sensor.Furthermore, the second A2L 970b sensor can be directly coupled to the last A2L 970c sensor via a 4-wire RS-485 harness connected between the output of bus connector 973 on the second A2L 970b sensor and the input of bus connector 972 on the last A2L 970c sensor. Additionally, the last A2L 970c sensor can be directly coupled to the A2L 950 control board via a feedback cable connected between the feedback port of sensor 975 on the last A2L 970c sensor and the connector of the second A2L 970c sensor. 958 of the A2L control board. A person skilled in the art, using common sense, will understand that the configuration of the A2L 970a, 970b, and 970c sensors, as described above with respect to Figure 9, can be used in any of the HVAC 100, 300, 500, and 700 systems described above with respect to Figures 1-8. Furthermore, although only one sensor architecture is shown in Figure 9, a person skilled in the art, using common sense, will understand that any A2L sensor can be used. Additionally, a person skilled in the art will understand that the sensor configuration shown in Figure 9 works with any A2L sensor that has a power input and a power output separated by any type of switch that prevents power from reaching the power output until the sensor has passed its internal diagnostics.Additionally, while the sensor architecture is described using a 4-wire RS-485 harness in several places, a person skilled in the art will understand that any method of connecting the sensors and the A2L control board that allows bidirectional communication—whether digital or analog, and wired or wireless—can be used. Furthermore, although three sensors are shown in Figure 9, a person skilled in the art will understand that two sensors can be used in series as described above, or a single sensor can be used instead. With reference to Figure 10, a flowchart of an installation and testing method for an A2L sensor configuration, as described above with respect to Figure 9, is illustrated for an HVAC system using an A2L refrigerant, according to one or more of the following modes. Method 1000 may include one or more of the following: (step 1010) placing the A2L sensors 970a, 970b, 970c inside the HVAC system 900; (step 1020) connecting the A2L sensors 970a, 970b, 970c to the A2L control board 950; (step 1030) powering on each of the A2L sensors 970a, 970b, 970c and running internal diagnostics; (step 1040) send confirmation to the A2L 950 control board that all A2L sensors are installed and functioning correctly. In step 1010, each of the A2L 970a, 970b, and 970c sensors can be placed within the HVAC 900 system as needed to ensure that any A2L refrigerant leaks are detected almost immediately. For example, placing the A2L 970a, 970b, and 970c sensors within the HVAC 900 system might include, at a minimum, finding a distinct location for each sensor adjacent to an evaporator coil of the HVAC 900 system's indoor unit and attaching each sensor to it. Furthermore, in step 1020, the A2L 970a, 970b, and 970c sensors can be coupled to the A2L 950 control board. Coupled to the A2L 970a, 970b, and 970c sensors may include, at least: (step 1021) connecting the first A2L iA / a / zu¿ó / uuoouu sensor 970a to the A2L 950 control board; (step 1022) connect the second A2L 970b sensor to the first A2L 970a sensor; (step 1023) connect the last A2L 970c sensor to the second A2L 970b sensor; and (step 1024) connect the last A2L 970c sensor to the A2L 950 control board. In step 1021, the first sensor of A2L 970a can be connected to the A2L 950 control board. Connecting the first sensor of A2L 970a to the A2L 950 control board may involve connecting an RS-485 bus at one end to a first sensor connector 957 on the A2L 950 control board and at the other end to a bus connector input 972 on the first sensor of A2L 970a. Additionally, in step 1022, the first sensor of A2L 970a can be connected to the second sensor of A2L 970b. In one or more modes, connecting the first A2L 970a sensor to the second A2L 970b sensor may involve connecting an RS-485 bus at one end to a bus connector output 973 of the first A2L 970a sensor and at the other end to a bus connector input 972 of the second A2L 970b sensor. Additionally, in step 1023, the second A2L 970b sensor may be connected to the last A2L 970c sensor.In one or more modes, connecting the second A2L 970b sensor to the last A2L 970c sensor may involve connecting an RS-485 bus at one end to a bus connector output 973 on the second A2L 970b sensor and at the other end to a bus connector input 972 on the last A2L 970c sensor. Additionally, in step 1024, the last A2L 970c sensor may be connected to the A2L 950 control board. In one or more modes, connecting the last A2L 970c sensor to the A2L 950 control board may involve connecting a feedback line at one end to a sensor feedback port 975 on the last A2L 970c sensor and at the other end to a second sensor connector 958 on the A2L 950 control board. In stage 1030, each of the A2L 970a, 970b, 970c sensors can be powered on and run internal diagnostics.The power-up and evaluation of each of the A2L sensors may include, at least: the first A2L 970a sensor (step 1031) receiving power from the A2L 950 control board (step 1032) runs an internal diagnostic test and, if it passes the internal diagnostic test, (step 1033) closes sensor relay 974 of the first A2L 970a sensor; the second A2L 970b sensor (step 1034) receiving power from the first A2L 970a sensor, (step 1035) runs an internal diagnostic test and, if it passes the internal diagnostic test, (step 1036) closes sensor relay 974 of the second A2L 970b sensor; The last A2L 970c sensor (step 1037) receives power from the second A2L 970b sensor, (step 1038) which runs an internal diagnostic test and, if it passed the internal diagnostic test, (step 1039) closes the sensor relay 974 of the last A2L 970c sensor. In step 1031, once the A2L 970a, 970b, and 970c sensors are physically coupled to the A2L 950 control board, the A2L 950 control board can send power to the first A2L 970a sensor, which the first A2L 970a sensor can receive and use to power up. Furthermore, in step 1032, the first A2L 970a sensor can perform an internal diagnostic check of the 971 sensing components, confirming whether the 971 sensing components are functioning correctly. Additionally, in step 1033, if the first A2L sensor 970a passed the internal diagnostic check, then the first sensor 970a can close the sensor relay 974, allowing power to travel from the input of bus connector 972 to the output of bus connector 973 and the feedback port of sensor 975. In step 1034, once the first A2L 970a sensor closes its sensor relay 974, it can send power to the second A2L 970b sensor, which the second A2L 970b sensor can receive and use to power itself on. Furthermore, in step 1035, the second A2L 970b sensor can perform an internal diagnostic check of the sensing components 971, confirming whether these components are functioning correctly. Additionally, in step 1036, if the second A2L 970b sensor passes the internal diagnostic check, it can close its sensor relay 974, allowing power to flow from the input of bus connector 972 to the output of bus connector 973 and the feedback port of sensor 975. In step 1037, once the second A2L 970b sensor closes its sensor relay 974, the second A2L 970b sensor can send power to the last A2L 970c sensor, which the last A2L 970c sensor can receive and use to power on. Furthermore, in step 1038, the last A2L 970c sensor can perform an internal diagnostic check of the sensing components 971, confirming whether the sensing components 971 are functioning correctly. Additionally, in step 1039, if the last A2L 970c sensor passes the internal diagnostic check, it can close the sensor relay 974, allowing power to flow from the input of bus connector 972 to the output of bus connector 973 and the feedback port of sensor 975. In stage 1040, once the last A2L 970c sensor closes its sensor relay 974, the last A2L 970c sensor can send power to the A2L 950 control board via the feedback line connected between the last A2L 970c sensor's feedback port 975 and the second sensor connector 958 on the A2L 950 control board. Receiving this feedback signal from the last A2L 970c sensor notifies the A2L 950 control board that all sensors in the network have successfully completed their internal checks, are functioning correctly, and there are no more sensors in the chain that need to be connected and evaluated.This is because, at any point in the sensor chain, if a sensor fails, the sensor relay will not close, and therefore all subsequent sensors in the chain and the feedback port of the last sensor in the chain will not receive power, and the A2L control board will not receive the feedback it needs. A person skilled in the art, using common sense, will understand that Method 1000 for installing and evaluating A2L sensors 970a, 970b, and 970c, as described above with respect to Figure 10, can be used with any of Methods 200, 400, 600, and 800 described above with respect to Figures 1–8. Furthermore, although only one sensor architecture is described in the method in Figure 10, a person skilled in the art, using common sense, will understand that any A2L sensor can be used. Additionally, a person skilled in the art will understand that the sensor configuration described in Method 1000 of Figure 10 works with any A2L sensor that has a power input and a power output separated by any type of switch that prevents power from reaching the power output until the sensor has passed its internal diagnostics.Additionally, while the sensor architecture is described using a 4-wire RS-485 harness in various places, a person skilled in the art will understand that any method of connecting the sensors and the A2L control board that allows bidirectional communication—whether digital or analog, and wired or wireless—can be used. Furthermore, although the installation and evaluation of three sensors is described using Method 1000, a person skilled in the art will understand that two sensors can be used in series in the same manner as described above, or a single sensor can be used instead. In this document, “or” is inclusive and not exclusive, unless expressly stated otherwise or indicated by the context. Therefore, in this document, A or B means A, B, or both, unless expressly stated otherwise or indicated by the context. Furthermore, “and” means both jointly and separately, unless expressly stated otherwise or indicated by the context. Therefore, in this document, A and B means A and B, jointly or separately, unless expressly stated otherwise or indicated by the context. The scope of this description encompasses all changes, substitutions, variations, alterations, and modifications to the example modalities described or illustrated herein that would be understood by a person of ordinary skill in the art. The scope of this description is not limited to the example modalities described or illustrated herein. Furthermore, although this description describes and illustrates the respective modalities herein that include particular components, elements, features, functions, operations, or steps, any of these modalities may include any combination or permutation of any of the components, elements, features, functions, operations, or steps described or illustrated anywhere herein that would be understood by a person of ordinary skill in the art.Furthermore, the reference in the appended claims to an apparatus or system or a component of an apparatus or system that is adapted, arranged for, capable of, configured for, enabled for, operable or operational for performing a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, switched on or unlocked, provided that such apparatus, system or component is adapted, arranged, capable, configured, enabled, operable or operational.

Claims

1. A system for detecting a quantity of R-32 refrigerant in an air temperature controller using an R-32 refrigerant, wherein the system comprises: an R-32 control board; and a first R-32 sensor and a second R-32 sensor electrically coupled to the R-32 control board, wherein each of the first R-32 sensor and the second R-32 sensor includes: sensing components configured to detect the quantity of R-32 refrigerant, wherein the first R-32 sensor and the second R-32 sensor are coupled in series to the R-32 control board.

2. The system of claim 1, wherein each of the first R-32 sensor and the second R-32 sensor further includes: a bus connector input; a bus connector output; a sensor relay electrically arranged between the bus connector input and the bus connector output; and a sensor feedback port electrically arranged between the bus connector input and the sensor feedback port.

3. The system of claim 2, wherein: the R-32 control board includes a first sensor connector and a second sensor connector; the bus connector input of the first R-32 sensor is electrically and communicatively coupled to the first sensor connector of the R-32 control board; the bus connector output of the first R-32 sensor is electrically and communicatively coupled to the bus connector input of the second R-32 sensor; and the sensor feedback port of the second R-32 sensor is electrically coupled to the second sensor connector of the R-32 control board.

4. The system of claim 3, wherein: the bus connector input of the first R-32 sensor is electrically and communicatively coupled to the first sensor connector of the R-32 control board by means of a first RS-485 connection; the bus connector output of the first R-32 sensor is electrically and communicatively coupled to the bus connector input of the second R-32 sensor by means of a second RS-485 connection; and the sensor feedback port of the second R-32 sensor is electrically coupled to the second sensor connector of the R-32 control board by means of a 24-volt AC connection.

5. The system of claim 3, wherein the system further comprises: an indoor unit located inside a building, wherein the indoor unit has a heat exchanger using R-32 refrigerant; a blower disposed within and electrically coupled to the indoor unit; and an outdoor unit located outside the building, wherein the outdoor unit is electrically connected to the indoor unit, and wherein the R-32 control board is electrically coupled to the indoor unit and the blower.

6. The system of claim 2, wherein: a first default state of the sensor relay of the first R-32 sensor is open; a second default state of the sensor relay of the second R-32 sensor is open; 7. The system of claim 6, wherein: the first R-32 sensor is configured to close the sensor relay of the first R-32 sensor if the first R-32 sensor passes an internal self-diagnostic test; and the second R-32 sensor is configured to close the sensor relay of the second R-32 sensor if the second R-32 sensor passes an internal self-diagnostic test.

8. The system of claim 7, wherein the second R-32 sensor does not receive power to turn on until the first R-32 sensor passes the internal self-diagnostic test and the sensor relay of the first R-32 sensor is closed.

9. The system of claim 8, wherein: the R-32 control board is configured to turn on the air temperature controller when it receives a feedback signal from the sensor feedback port of the second R-32 sensor; and the sensor feedback port of the second R-32 sensor does not receive power to send the feedback signal until the second R-32 sensor passes the internal self-diagnostic test and the sensor relay of the second R-32 sensor is closed.

10. The system of claim 1, wherein the first R-32 sensor is configured to communicate with the R-32 control board if the first R-32 sensor detects that the amount of R-32 refrigerant exceeds a leakage threshold, and wherein the second R-32 sensor is configured to communicate with the R-32 control board if the second R-32 sensor detects that the amount of leaking R-32 refrigerant exceeds a leakage threshold.

11. A method for installing an R-32 sensor configuration in an air temperature controller using an R-32 refrigerant, wherein the method comprises: placing an R-32 control board, a first R-32 sensor, and a second R-32 sensor in an air temperature controller; electrically coupling the first R-32 sensor to the R-32 control board; and electrically coupling the second R-32 sensor to the R-32 control board, wherein the first R-32 sensor and the second R-32 sensor each include sensing components configured to detect a quantity of R-32 refrigerant, and wherein the first R-32 sensor and the second R-32 sensor are coupled in series to the R-32 control board.

12. The method of claim 11, wherein: each of the first R-32 sensor and the second R-32 sensor further includes: a bus connector input; a bus connector output; a sensor relay electrically arranged between the bus connector input and the bus connector output; and a sensor feedback port electrically arranged between the bus connector input and the sensor feedback port; and the R-32 control board includes a first sensor connector and a second sensor connector.

13. The system of claim 12, further comprising: electrically and communicatively coupling the bus connector input of the first R-32 sensor to the first sensor connector of the R-32 control board; electrically and communicatively coupling the bus connector output of the first R-32 sensor to the bus connector input of the second R-32 sensor; and electrically coupling the sensor feedback port of the second R-32 sensor to the second sensor connector of the R-32 control board.

14. The device of claim 13, wherein: electrically and communicatively coupling the bus connector input of the first R-32 sensor to the first sensor connector of the R-32 control board by means of a first RS-485 connection; electrically and communicatively coupling the bus connector output of the first R-32 sensor to the bus connector input of the second R-32 sensor by means of a second RS-485 connection; and electrically coupling the sensor feedback port of the second R-32 sensor to the second sensor connector of the R-32 control board by means of a 24-volt AC connection.

15. The system of claim 13, further comprising: placing an indoor unit inside a building, wherein the indoor unit has a heat exchanger using R-32 refrigerant; placing a blower inside the indoor unit and electrically coupling the blower to the indoor unit; placing an outdoor unit outside the building and electrically coupling the outdoor unit to the indoor unit; and electrically coupling the R-32 control board to the indoor unit and the blower.

16. The system of claim 12, wherein: a first default state of the sensor relay of the first R-32 sensor is open; a second default state of the sensor relay of the second R-32 sensor is open; 17. The system of claim 16, further comprising: performing a first internal self-diagnostic test on the first R-32 sensor; closing the sensor relay of the first R-32 sensor if the first R-32 sensor passes the first internal self-diagnostic test; performing a second internal self-diagnostic test on the second R-32 sensor; and closing the sensor relay of the second R-32 sensor if the second R-32 sensor passes the second internal self-diagnostic test.

18. The system of claim 17, wherein the second R-32 sensor does not receive power to turn on until the first R-32 sensor passes the first internal self-diagnostic test and the sensor relay of the first R-32 sensor is closed.

19. The system of claim 18, further comprising: Turning on the air temperature controller by means of the R-32 control board when the R-32 control board receives a feedback signal from the sensor feedback port of the second R-32 sensor, wherein the R-32 control board does not receive the feedback signal from the sensor feedback port of the second R-32 sensor until the second R-32 sensor passes the second internal self-diagnostic test and the sensor relay of the second R-32 sensor closes.

20. The system of claim 11, wherein the first R-32 sensor is configured to communicate with the R-32 control board if the first R-32 sensor detects that the amount of R-32 refrigerant exceeds a leakage threshold, and wherein the second R-32 sensor is configured to communicate with the R-32 control board if the second R-32 sensor detects that the amount of R-32 refrigerant exceeds a leakage threshold.

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