Low-voltage direct-current gas water heater and electric safety control system thereof

Abstract

The present application relates to gas water heater technical field, disclose a kind of low pressure direct current gas water heater and its electric safety control system, including the gas water heater main body with main controller and power adapter;Wherein, power adapter includes AC input connector, safety isolation transformer and rectifier device, voltage detection module and output control and communication module, safety isolation transformer and rectifier device are used to voltage rectification to obtain stable safety low voltage and output to main controller, voltage detection module is used to detect the AC voltage of power grid, and output control and communication module are used to load frequency signal on output voltage.The present application has the input under-voltage protection function of electric safety detection: when power adapter detects that input voltage is low, signal is sent to gas water heater main body, so that gas water heater main body actively limits maximum power;Prevent power device in power adapter from overheating and burning, also prevent power adapter from not working normally, leading to unstable output voltage.

Description

Technical Field

[0001] This invention relates to the field of gas water heater technology, and in particular to a low-voltage DC gas water heater and its electrical safety control system. Background Technology

[0002] Currently, the safety protection measures for gas water heaters are based on normal installation environments. When a water heater leaks electricity, the leakage current is mainly conducted to the ground through a protective grounding wire, and the input power is cut off by the user's residual current device (RCD). However, this cannot handle situations where the grounding wire is live. Existing water leak detection methods involve installing a water flow sensor at each of the inlet and outlet, and determining whether there is an internal leak by the difference in the readings from the two sensors. Existing gas leak detection methods involve using a natural gas detector to detect a natural gas leak and then issuing an alarm to notify the user to check.

[0003] However, in practical applications, it has been found that due to the complex installation and usage environment, existing safety protection measures still have some water, electricity, and gas-related safety hazards. For example: 1) Protection through protective grounding wires and residual current devices cannot avoid the risk of electric shock caused by live grounding wires; 2) Due to errors between water flow sensors, parameter calibration is troublesome, and small-flow leaks cannot be detected; 3) When monitoring natural gas leaks, only an alarm is issued without protective measures, and natural gas continues to accumulate in the room, posing a safety hazard; moreover, the location of the leak cannot be identified.

[0004] A Chinese invention patent application with publication number CN105823219A discloses a safe gas water heater using DC power, which includes at least a DC fan and a wire for connecting to an external power source. A power adapter is also connected between the gas water heater and the external power source, converting the AC power from the external power source to DC power to ensure electrical safety. However, the power adapter needs to meet insulation and waterproof requirements, and generally uses a plastic casing, resulting in reliance on passive heat dissipation, which can easily lead to overheating and burnout or unstable operation. Summary of the Invention

[0005] This invention proposes a low-voltage DC gas water heater with electrical safety detection and over-temperature protection, which provides at least one beneficial option or creates conditions to solve one or more technical problems existing in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A power safety control system for a low-voltage DC gas water heater includes a gas water heater body with a main controller and a power adapter for supplying power to it; wherein, the power adapter includes an AC input connector, a safety isolation transformer and rectifier, a voltage detection module, and an output control and communication module, the safety isolation transformer and rectifier are used to transform and rectify to obtain a stable safe low voltage and output it to the main controller, the voltage detection module is used to detect the AC voltage of the power grid, and the output control and communication module is used to load a frequency signal onto the output voltage.

[0008] The main controller includes a separation and decoding module and a main control chip. The separation and decoding module is used to separate the frequency signal loaded on the output voltage, and the main control chip is used to identify the frequency signal and perform power control.

[0009] During operation, the power adapter obtains AC power from the power grid through the AC input connector, and then obtains a stable safety extra-low voltage through the safety isolation transformer and rectifier. Finally, it is output from the output control and communication module. The voltage detection module detects the AC voltage U of the power grid and compares it with the set minimum voltage Umin. When the AC voltage U is lower than Umin, a high-frequency pulse signal of frequency k1 is loaded onto the output voltage through the output control and communication module. After the high-frequency pulse signal reaches the main controller, the pulse signal k1 is separated from the supply voltage by the separation and decoding module and sent to the main controller chip for identification. The main controller chip limits the maximum power of the gas water heater body to (Umin / 220V) × rated power according to the identified signal and issues an alarm for low input voltage.

[0010] More preferably, the power adapter includes a temperature probe used to detect the internal ambient temperature T of the power adapter and compare it with a set maximum temperature Tmax.

[0011] When T is greater than Tmax, a high-frequency pulse signal of frequency k2 is applied to the output voltage through the output control and communication module. After the high-frequency pulse signal reaches the main controller, the separation and decoding module separates the pulse signal k2 from the supply voltage and sends it to the main controller chip for identification. The main controller chip reduces the overall power by one percentage based on the identified signal and issues an alarm. After waiting for a period of time, the internal ambient temperature T of the power adapter is detected again. If the temperature T is still higher than Tmax, the overall power is reduced by one percentage until T is less than Tmax. When the internal ambient temperature T of the power adapter is detected to be less than the set minimum temperature Tmin, the power of the gas water heater body is restored to 100%.

[0012] More preferably, the percentage is 3%-10%.

[0013] More preferably, the duration of the waiting period is 0.5-5 minutes.

[0014] On the other hand, the present invention also provides a low-voltage DC gas water heater, which has an electrical safety control system for a low-voltage DC gas water heater as described above.

[0015] More preferably, a leak detection probe connected to the main controller is installed on the main body of the gas water heater. The leak detection probe includes an insulated terminal base and a detection terminal installed on the terminal base.

[0016] The leak detection probe is installed at the bottom of the metal casing of the gas water heater body and fixed to the metal casing of the water heater by metal screws; the detection terminal is insulated from the metal casing by the terminal base; the main controller is connected to the detection terminal by wire and applies a high-level signal to the detection terminal, and the main controller connects the signal ground wire to the metal casing, so that the metal screw and the signal ground wire are electrically connected through the metal casing.

[0017] When the main body of the gas water heater leaks, the water will gather at the bottom of the metal casing. When the water gathers to a certain extent, an electrical connection is formed between the detection terminal and the metal screw through the water, thereby pulling the high-level signal of the detection terminal low. When the main controller detects that the potential of the leak detection probe is low, it determines that a leak has occurred.

[0018] More preferably, a raised platform is provided on the terminal base, and the detection terminal is mounted on the raised platform and raised thereon.

[0019] More preferably, two or more leak detection probes are installed on the metal casing of the gas water heater body; when the gas water heater body leaks, the number of leak detection probes with low potential is determined. If the number is 1, only a leak alarm is issued; if the number is 2 or more, hot water use is prohibited and a leak alarm is issued.

[0020] More preferably, a natural gas detector and a fan connected to the main controller are installed on the main body of the gas water heater; when the natural gas detector detects that the concentration Q of natural gas in the environment exceeds the standard, the fan is started to exhaust gas and a gas leak alarm is issued.

[0021] More preferably, if the natural gas concentration Q decreases to Q1 within time t, it is determined that there is a gas leak inside the main body of the gas water heater; if the natural gas concentration Q does not decrease to Q1 within time t, it is determined that there is a gas leak outside the main body of the gas water heater.

[0022] The technical solution provided by this invention has at least the following technical effects or advantages.

[0023] 1. Input undervoltage protection function with electrical safety detection: When the power adapter detects that the input voltage is too low, it sends a signal to the main body of the gas water heater, causing the main body of the gas water heater to actively limit the maximum power; to prevent the power devices in the power adapter from overheating and burning out, and also to prevent the output voltage from being unstable due to abnormal operation of the power adapter.

[0024] II. Over-temperature protection with electrical safety detection: The power adapter, needing to meet insulation and waterproofing requirements, uses a plastic casing, resulting in passive heat dissipation. An internal temperature probe detects the temperature, and when it exceeds a set value, a signal is sent to the water heater, causing it to actively adjust its power output. This prevents the power components inside the adapter from overheating and burning out, and also prevents unstable output voltage caused by abnormal adapter operation.

[0025] 3. It has a gas leak detection function: after detecting a natural gas leak, it starts the fan to vent the gas and tests the venting efficiency. This can determine whether the gas leak is inside or outside the water heater, helping users to solve the gas leak problem more quickly.

[0026] IV. Leakage Detection Function: Based on the design of gas water heaters without a protective ground wire, a leakage detection method is proposed. The metal casing of the water heater forms an electrical connection, making the structure of the leakage detection probe simple, easy to install, and suitable for multiple probes to be installed together for judgment, thereby realizing the judgment of the degree of leakage.

[0027] 5. The external power adapter is connected to the gas water heater via two wires, enabling power supply and communication. Since the main body of the gas water heater uses extra-low voltage, it can be considered that the main body of the gas water heater is not electrified, and there is no need to install a protective ground wire. This avoids the safety hazards caused by the ground wire of the power grid being electrified and the signal interference to electrical components. Attached Figure Description

[0028] Figure 1 The diagram shown is a structural schematic of the low-voltage DC gas water heater provided by the present invention.

[0029] Figure 2 The diagram shows the power adapter supplying power to the water heater and communicating with it.

[0030] Figure 3 The diagram shown is a flowchart of the input undervoltage protection process.

[0031] Figure 4 The diagram shown is a flowchart of the power adapter over-temperature protection process.

[0032] Figure 5 The diagram shown is a structural schematic of a water leakage detection terminal.

[0033] Figure 6 The diagram shown is a flowchart for leak detection.

[0034] Figure 7 The diagram shows a schematic of a multi-point leak detection system.

[0035] Figure 8 The flowchart shown is for multi-point leak detection.

[0036] Figure 9 The flowchart shown is for leak detection and protection.

[0037] Explanation of the reference numerals in the attached figures.

[0038] 1: Power adapter, 2: Water heater body, 3: Main controller, 4: Leakage detection probe, 5: Metal screw, 6: Signal ground wire, 7: Water flow sensor, 8: Natural gas detector, 9: DC fan.

[0039] 1-1: AC input connector; 1-2: Safety isolation transformer and rectifier; 1-3: Voltage detection module; 1-4: Output control and communication module; 1-5: Temperature probe.

[0040] 3-1: Separate decoding module; 3-2: Main controller chip.

[0041] 4-1: Detection terminal; 4-2: Terminal base.

[0042] 41: First leakage detection terminal; 42: Second leakage detection terminal. Detailed Implementation

[0043] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings, making the technical solution and beneficial effects of the present invention clearer and more explicit. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0044] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention.

[0045] Reference Figure 1 As shown, a low-voltage DC gas water heater includes a gas water heater body 2, and a main controller 3, a leak detection probe 4, a water flow sensor 7, a natural gas detector 8, and a fan 9 installed on the gas water heater body 2. The main controller 3 is connected to the leak detection probe 4, the water flow sensor 7, the natural gas detector 8, and the fan 9. A power adapter 1 for supplying power is also connected to the main controller 3.

[0046] Since the AC220V from the power grid is converted into a safe extra-low DC voltage via the power adapter 1, and then connected to the main controller 3 via two wires to the water heater body 2, there is no need to ground the metal casing of the water heater body 2, thus avoiding various dangers caused by a live ground wire in the user's home. The signal ground wire 6 of the main controller 3 is fixed to the metal casing of the water heater body 2 through direct connection or indirect connection via series resistor, preventing static electricity from accumulating on the metal casing; it also provides a reference ground for internal electrical signals.

[0047] Reference Figure 2 As shown, the power adapter 1 includes an AC input connector 1-1, a safety isolation transformer and rectifier 1-2, a voltage detection module 1-3, an output control and communication module 1-4, and a temperature probe 1-5. The AC input connector 1-1 is used to obtain AC power from the power grid. The safety isolation transformer and rectifier 1-2 is used to transform and rectify to obtain a stable, safe low voltage. The voltage detection module 1-3 is used to detect the AC voltage of the power grid. The output control and communication module 1-4 is used to apply a frequency signal to the output voltage. The temperature probe 1-5 is used to detect the temperature of the power adapter 1. The main controller 3 includes a separation and decoding module 3-1 and a main control chip 3-2. The separation and decoding module 3-1 is used to separate the frequency signal applied to the output voltage. The main control chip 3-2 is used to identify the frequency signal and perform power control.

[0048] Combination Figure 3 As shown, this is a process for input undervoltage protection via power adapter 1. Power adapter 1 obtains AC power from the power grid through AC input connector 1-1, then obtains a stable safety extra-low voltage through a safety isolation transformer and rectifier 1-2, and finally outputs it from the output control and communication module 1-4. The voltage detection module 1-3 detects the AC voltage U of the power grid and compares it with the minimum value Umin. When the AC voltage U is lower than Umin, the output control and communication module 1-4 applies a high-frequency pulse signal of frequency k1 to the output voltage. This high-frequency pulse signal reaches the main controller 3, where the separation and decoding module 3-1 separates the pulse signal k1 from the supply voltage and sends it to the main controller chip 3-2 for identification. The main controller chip 3-2 limits the maximum power of the water heater to (Umin / 220V) × rated power to prevent power devices from overheating and burning out due to high current, and issues an input voltage undervoltage alarm.

[0049] Combination Figure 4The diagram illustrates the over-temperature protection process of the power adapter. Since the power adapter 1 has a plastic casing, it relies solely on passive heat dissipation. Therefore, the ambient temperature T inside the power adapter is detected by temperature probes 1-5. When T exceeds Tmax, it indicates that the internal ambient temperature is approaching the maximum operating temperature of the electronic components. At this point, a high-frequency pulse signal of frequency k2 is applied to the output voltage via the output control and communication module 1-4. This high-frequency pulse signal reaches the main controller 3, where it is separated from the supply voltage by the decoupling and decoding module 3-1 and sent to the main controller chip 3-2 for identification. The main controller chip 3-2 reduces the overall power by 5% and issues an alarm, waiting 1 minute before re-detecting the internal temperature T of the power adapter. If the temperature T is still higher than Tmax, the overall power is further reduced until T is less than Tmax, effectively extending the lifespan of the electronic components. When the detected temperature T is less than Tmin, the power of the water heater body is restored to 100%.

[0050] It should be noted that the selection of product models and connection circuit design for safety isolation transformers, rectifiers, voltage detection modules, output control and communication modules, separation and decoding modules, main control chips, and temperature probes are all common technical knowledge mastered by those skilled in the art, and will not be elaborated here.

[0051] Leak detection.

[0052] Combination Figure 5 As shown, the leak detection probe 4 is installed at the bottom of the water heater's metal casing and fixed to it with metal screws 5. The detection terminal 4-1 of the leak detection probe 4 is insulated from the water heater's metal casing via a terminal base 4-2. The main controller 3 connects to the detection terminal 4-1 via a wire and applies a high-level signal to it. Furthermore, the main controller 3 connects the signal ground wire 6 to the metal casing of the water heater body 2, thus electrically connecting the metal screws 5 and the signal ground wire 6 through the metal casing.

[0053] Combination Figure 6 As shown, when the gas water heater body 2 leaks, the water will gather at the bottom of the metal casing. Because water is a conductor, when the water gathers to a certain level, an electrical connection is formed between the detection terminal 4-1 and the metal screw 5 through the water. Since the metal screw 5 and the signal ground wire 6 are electrically connected, a connection is also formed between the detection terminal 4-1 and the signal ground wire 6, causing the high-level signal of the detection terminal 4-1 to be pulled low. When the main controller 3 detects that the potential of the leak detection probe 4 is low, it determines that a leak has occurred, prohibits the use of hot water, and issues a leak alarm.

[0054] In this embodiment, the leak detection probe 4 consists of a detection terminal 4-1 and an insulated terminal base 4-2. During installation, it is simply fixed to the metal casing of the gas water heater body 2 using metal screws 5. The leak detection probe has a simple installation structure, small size, and allows for the installation of multiple probes to form multi-point leak detection. Simultaneously, the terminal base 4-2 of the leak detection probe has a raised platform that elevates the detection terminal 4-1. Only when the leak reaches a certain level can an electrical connection be formed between the detection terminal 4-1 and the metal screw 5 through water. This prevents false alarms caused by condensation droplets.

[0055] Combination Figure 7 , Figure 8 As shown, a first leak detection terminal 41 and a second leak detection terminal 42 are preferably installed on the metal casing of the gas water heater body 2. When the water heater leaks, a connection is formed between the detection terminal 41 and the signal ground wire 6. At this time, the number of leak detection probes with low potential is determined. If the number is one, it indicates a minor leak, and only a leak alarm is issued, allowing the user to use hot water while waiting for repairs. If the number is two, it indicates a major leak, prohibiting the use of hot water and issuing a leak alarm. Obviously, those skilled in the art can also set three, four, or even more leak detection terminals according to different actual needs, and are not limited to this embodiment.

[0056] Leak detection.

[0057] Combination Figure 9 As shown, when the natural gas detector 8 detects that the concentration of natural gas Q in the environment exceeds the standard, it considers a natural gas leak to have occurred, starts the fan to ventilate, and issues a leak alarm. If the natural gas concentration Q decreases to Q1 within time t, it indicates a leak inside the water heater, and the user is notified. If the natural gas concentration Q does not decrease to Q1, it indicates poor venting, meaning a leak occurs outside the water heater, and the user is notified.

[0058] In this embodiment, the natural gas detector 8 is preferably installed at the highest possible position inside the gas water heater body 2, so that natural gas leaks can be detected more quickly.

[0059] It should be noted that the specific values ​​of time t and natural gas concentration Q1 are obtained by those skilled in the art based on experience or limited experiments, and are common technical knowledge possessed by those skilled in the art.

[0060] Compared with the prior art, the low-voltage DC gas water heater provided in this embodiment has the following characteristics: 1) The external power adapter 1 outputs a safe extra-low voltage to power the water heater through a safety isolation transformer, so that no protective ground wire needs to be installed inside the water heater. When the ground wire in the user's home is live, the current cannot form an electrical connection between the power adapter 1 and the metal casing of the water heater, so it will not interfere with the internal circuit of the water heater, nor will it cause any leakage risk to the metal casing.

[0061] 2) Leakage detection: The leakage detection probe uses the metal casing of the water heater for electrical connection to detect leaks. It has a simple structure and is suitable for installing multiple probes for combined judgment to determine the degree of leakage.

[0062] 3) Input undervoltage protection for electrical safety detection: When the power adapter detects a low input voltage, it sends a signal to the water heater, causing the water heater to actively limit its maximum power. This prevents the power components inside the power adapter from overheating and burning out, and also prevents unstable output voltage caused by abnormal operation of the power adapter.

[0063] 4) Over-temperature protection for electrical safety: The power adapter needs to meet insulation and waterproof requirements, so it uses a plastic casing, which means it can only rely on passive heat dissipation. An internal temperature probe detects the temperature, and when the temperature exceeds a set value, it sends a signal to the water heater, causing the water heater to actively adjust its power. This prevents the power components inside the power adapter from overheating and burning out, and also prevents unstable output voltage caused by abnormal operation of the power adapter.

[0064] 5) Gas Leak Detection: After detecting a natural gas leak, the fan is started to vent the gas and the venting efficiency is tested. This can determine whether the leak is inside or outside the water heater, helping users resolve gas leak problems more quickly.

[0065] It should also be noted that in the description of this invention, directional terms such as "center," "lateral," "longitudinal," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0066] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "at least" means one or more, unless otherwise explicitly specified.

[0067] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0068] In this invention, unless otherwise specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "below," and "over" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Above," "below," and "below" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0069] Based on the above description of the structure and principles, those skilled in the art should understand that this invention is not limited to the specific embodiments described above. Improvements and substitutions made using techniques known in the art based on this invention all fall within the scope of protection of this invention, which should be defined by the claims and their equivalents. Parts not described in the specific embodiments are all prior art or common knowledge.

Claims

1. An electrical safety control system for a low-voltage DC gas water heater, comprising a gas water heater body with a main controller and a power adapter for supplying power to it; characterized in that, The power adapter includes an AC input connector, a safety isolation transformer and rectifier, a voltage detection module, and an output control and communication module. The safety isolation transformer and rectifier are used to transform and rectify to obtain a stable safe low voltage and output it to the main controller. The voltage detection module is used to detect the AC voltage of the power grid. The output control and communication module is used to load a frequency signal onto the output voltage. The main controller includes a separation and decoding module and a main control chip. The separation and decoding module is used to separate the frequency signal loaded on the output voltage, and the main control chip is used to identify the frequency signal and perform power control. During operation, the power adapter obtains AC power from the power grid through the AC input connector, and then obtains a stable safety extra-low voltage through the safety isolation transformer and rectifier. Finally, it is output from the output control and communication module. The voltage detection module detects the AC voltage U of the power grid and compares it with the set minimum voltage Umin. When the AC voltage U is lower than Umin, a high-frequency pulse signal of frequency k1 is loaded onto the output voltage through the output control and communication module. After the high-frequency pulse signal reaches the main controller, the pulse signal k1 is separated from the supply voltage by the separation and decoding module and sent to the main controller chip for identification. The main controller chip limits the maximum power of the gas water heater body to (Umin / 220V) × rated power according to the identified signal and issues an alarm for low input voltage.

2. The electrical safety control system for a low-voltage DC gas water heater according to claim 1, characterized in that, The power adapter includes a temperature probe, which is used to detect the internal ambient temperature T of the power adapter and compare it with the set maximum temperature Tmax. When T is greater than Tmax, a high-frequency pulse signal of frequency k2 is applied to the output voltage through the output control and communication module. After the high-frequency pulse signal reaches the main controller, the separation and decoding module separates the pulse signal k2 from the supply voltage and sends it to the main controller chip for identification. The main controller chip reduces the overall power by one percentage based on the identified signal and issues an alarm. After waiting for a period of time, the internal ambient temperature T of the power adapter is detected again. If the temperature T is still higher than Tmax, the overall power is reduced by one percentage until T is less than Tmax. When the internal ambient temperature T of the power adapter is detected to be less than the set minimum temperature Tmin, the power of the gas water heater body is restored to 100%.

3. The electrical safety control system for a low-voltage DC gas water heater according to claim 2, characterized in that, The percentage is 3%-10%.

4. The electrical safety control system for a low-voltage DC gas water heater according to claim 2, characterized in that, The waiting period is 0.5-5 minutes.

5. A low-voltage DC gas water heater, characterized in that, The device has an electrical safety control system for a low-voltage DC gas water heater as described in any one of claims 1-4.

6. A low-voltage DC gas water heater according to claim 5, characterized in that, A leak detection probe connected to the main controller is installed on the main body of the gas water heater. The leak detection probe includes an insulated terminal base and a detection terminal installed on the terminal base. The leak detection probe is installed at the bottom of the metal casing of the gas water heater body and is fixed to the metal casing of the water heater by metal screws; the detection terminal is insulated from the metal casing by the terminal base; the main controller is connected to the detection terminal by wire and applies a high-level signal to the detection terminal, and the main controller connects the signal ground wire to the metal casing, so that the metal screw and the signal ground wire are electrically connected through the metal casing; When the main body of the gas water heater leaks, the water will gather at the bottom of the metal casing. When the water gathers to a certain extent, an electrical connection is formed between the detection terminal and the metal screw through the water, thereby pulling the high-level signal of the detection terminal low. When the main controller detects that the potential of the leak detection probe is low, it determines that a leak has occurred.

7. A low-voltage DC gas water heater according to claim 6, characterized in that, A raised platform is provided on the terminal base, and the detection terminal is mounted on the raised platform and raised by it.

8. A low-voltage DC gas water heater according to claim 6, characterized in that, Two or more leakage detection probes are installed on the metal casing of the gas water heater body; When the main body of the gas water heater leaks, the number of leak detection probes with low potential is determined. If the number is 1, only a leak alarm is issued. If the number is 2 or more, hot water use is prohibited, and a leak alarm is issued.

9. A low-voltage DC gas water heater according to claim 5, characterized in that, A natural gas detector and a fan connected to the main controller are installed on the main body of the gas water heater; when the natural gas detector detects that the concentration Q of natural gas in the environment exceeds the standard, the fan is started to exhaust gas and a gas leak alarm is issued.

10. A low-voltage DC gas water heater according to claim 9, characterized in that, If the natural gas concentration Q decreases to Q1 within time t, it is determined that there is an internal gas leak in the main body of the gas water heater; if the natural gas concentration Q does not decrease to Q1 within time t, it is determined that there is an external gas leak in the main body of the gas water heater.

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