Water heater, program and control method thereof

Abstract

To monitor a combustion state of a burner regularly and execute combustion improvement thereof, regardless of a combustion mode by a hot water supply request.SOLUTION: A water heater comprises: a first burner unit (6-1) that is burnt in a first combustion mode; a second burner unit (6-2) that is burnt in a second combustion mode in a combustion amount exceeding that in the first combustion mode; and a control unit (5) that sets the combustion amount according to a hot water supply request, selects the first combustion mode or the second combustion mode, performs a hot water supply process in accordance with the continuing hot water supply request when a cumulative time of the second combustion mode during combustion reaches a certain time or more, ends the hot water supply processing when there is no longer the hot water supply request, and when the hot water supply request occurs after the completion of the hot water supply processing, burns the first burner unit so that it is burnt in the first combustion mode regardless of the content of the hot water supply request.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to combustion control that monitors and adjusts the combustion state of a combustion unit mounted in a water heater. [Background technology]

[0002] A known water heater has multiple burners divided into groups of several burners, and by combining the divided burner groups in response to hot water supply demands, it burns the number of burners necessary to obtain the required combustion amount (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-128575 Summary of the Invention [Problem to be solved by the invention]

[0004] In water heaters, the combustion state of the burner is regularly monitored. This combustion state is greatly affected by the amount of air supplied to the burner. Depending on the ratio of fuel gas to air, the amount of NOx generated by combustion changes, and there is also the risk of incomplete combustion in the burner. In water heaters, combustion improvement processing is performed based on the results of the combustion state monitoring. Flame rods are used to monitor the combustion state, but the number that can be installed in a water heater is limited due to cost, installation space, and other factors. Therefore, because the combustion section of a water heater is divided into several burners, there are sections whose combustion state cannot be monitored with a flame rod, and the combustion state of these burners cannot be adjusted. In the case of a water heater that uses only a hot water supply pipe, such as a single-pipe system, or a central hot water supply system that supplies hot water to multiple hot water loads, fluctuations in the hot water load are small, so combustion may continue only in the burner section where no flame rod is installed. In this case, the water heater may continue to be unable to monitor the combustion state of the burner or improve the combustion. Patent Document 1 does not disclose or suggest anything about such a problem, and the configuration disclosed in Patent Document 1 cannot solve such a problem.

[0005] In view of the above, an object of the present invention is to periodically monitor the combustion state of the burner and improve the combustion, regardless of the combustion mode selected in response to a hot water supply request. [Means for solving the problem]

[0006] In order to achieve the above object, according to one aspect of the water heater of the present invention, there is provided a water heater including a first burner unit that burns in a first combustion mode, a second burner unit that burns in the first combustion mode and a second combustion mode at a combustion amount exceeding that of the first burner unit, a flame sensor that is installed in the first burner unit and detects a flame, and a water heater that sets the combustion amount in response to a hot water supply request. , by combustion of the first burner section alone The first combustion mode the first combustion mode by combustion using a combination of the first burner section and the second burner section; Alternatively, the apparatus includes a control unit that selects the second combustion mode, and when the cumulative time of the second combustion mode during combustion reaches or exceeds a certain time, performs hot water supply processing in accordance with the ongoing hot water supply request, and terminates the hot water supply processing when the hot water supply request disappears, and after this termination, when a hot water supply request occurs, causes the first burner unit to burn in the first combustion mode regardless of the content of the hot water supply request, and the control unit acquires a flame current value from the flame sensor, and increases or decreases the rotation speed of the air supply fan based on the result of comparing this flame current value with an ideal value. In this water heating device, the control unit may use a combustion mode switching table to adjust combustion, including changing the number of combustion stages of the first burner unit or the second burner unit or monitoring the combustion state, to change the hot water temperature based on the limit value to which the number of combustion stages can be increased, and may select a hot water temperature that results in three-stage combustion within a range in which the hot water flow rate is greater than the limit threshold value.

[0007] In order to achieve the above object, according to one aspect of the program of the present invention, there is provided a program for controlling a water heater using a computer, the program including: a function for burning a first burner unit in a first combustion mode; a function for burning a second burner unit at a combustion amount exceeding that of the first burner unit in the first combustion mode and a second combustion mode; a function for detecting a flame with a flame sensor installed in the first burner unit; and a function for setting the combustion amount in accordance with a hot water supply request. , by combustion of the first burner section alone The first combustion mode the first combustion mode by combustion using a combination of the first burner section and the second burner section; Alternatively, the computer may select the second combustion mode, and when the cumulative time of the second combustion mode during combustion reaches or exceeds a certain time, perform hot water supply processing in accordance with the ongoing hot water supply request, and terminate the hot water supply processing when the hot water supply request disappears. After this processing is terminated, when a hot water supply request occurs, the computer may perform the following functions: burning the first burner section so that the first combustion mode is selected regardless of the content of the hot water supply request; and acquiring a flame current value from the flame sensor, and increasing or decreasing the rotation speed of the air supply fan based on the result of comparing this flame current value with an ideal value.

[0008] In order to achieve the above object, one aspect of the method for controlling a water heater of the present invention includes a step of burning a first burner unit in a first combustion mode, a step of burning a second burner unit in the first combustion mode and a second combustion mode at a combustion amount exceeding that of the first burner unit, a step of detecting a flame with a flame sensor installed in the first burner unit, and a step of setting the combustion amount in accordance with a hot water supply request. , by combustion of the first burner section alone The first combustion mode the first combustion mode by combustion using a combination of the first burner section and the second burner section;Alternatively, the method includes a step of selecting the second combustion mode, and when the cumulative time of the second combustion mode during combustion reaches or exceeds a certain time, performing hot water supply processing in accordance with the ongoing hot water supply request, and terminating the hot water supply processing when the hot water supply request disappears, and when a hot water supply request occurs after this is completed, burning the first burner section so that the first combustion mode is selected regardless of the content of the hot water supply request, and a step of acquiring a flame current value from the flame sensor, and increasing or decreasing the rotation speed of the air supply fan based on the result of comparing this flame current value with an ideal value. [Effects of the Invention]

[0009] According to the present invention, one of the following effects can be obtained. (1) If combustion continues in the second combustion mode where the flame sensor cannot detect the combustion state, the combustion mode can be changed and the amount of air contained in the mixture to the burner can be adjusted based on the detection output of the flame sensor, thereby improving the safety of the water heater and reducing the environmental impact caused by combustion.

[0010] (2) By using a flame sensor installed in part of the first burner section and performing monitoring processing according to the first combustion mode or the second combustion mode based on the hot water supply request, it is possible to grasp the combustion state of the burner while reducing the number of parts.

[0011] (3) Regardless of the combustion control based on the hot water supply request, the combustion state can be monitored periodically or quantitatively, thereby improving the reliability of the combustion control.

[0012] (4) In the combustion state monitoring process, the hot water supply temperature can be prevented from dropping or rising below the set temperature, and the outlet hot water temperature can be stabilized. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of a configuration of a water heater according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing an example of a switching state of the number of combustion stages. [Figure 3] 10 is a flowchart illustrating an example of a hot water supply process. [Figure 4] FIG. 10 is a diagram illustrating an example of the configuration of a water heater according to a second embodiment. [Figure 5] 10 is a flowchart illustrating an example of a hot water supply process. [Figure 6] 1 is a diagram illustrating a configuration example of a water heater according to a first embodiment. [Figure 7] FIG. 2 is a diagram illustrating an example of the configuration of a control device. [Figure 8] FIG. 10 is a diagram showing an example of a monitoring process of a combustion state by a flame rod. [Figure 9] FIG. 4 is a diagram showing an example of the timing of a combustion state monitoring process. [Figure 10] 10 is a flowchart illustrating an example of a hot water supply process. [Figure 11] 4 is a flowchart showing an example of a combustion improvement process. [Figure 12] FIG. 10 is a diagram illustrating a configuration example of a water heater according to a second embodiment. [Figure 13] FIG. 4 is a diagram showing an example of a combustion mode switching table. [Figure 14] 10 is a flowchart illustrating an example of a hot water supply process. [Figure 15] 10 is a flowchart showing an example of a hot water supply process according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] [First embodiment] <Hot water supply device 2> Fig. 1 shows an example of the configuration of a water heater according to the first embodiment. The configuration shown in Fig. 1 is just an example, and the present invention is not limited to this configuration. 1, water heater 2 includes a combustion unit 4 that burns fuel gas to generate high-temperature combustion exhaust, and a control unit 5 that has at least the functions of controlling the combustion of combustion unit 4, monitoring the combustion state, and adjusting the operation. Water heater 2 may have combustion unit 4 and control unit 5 housed in the same housing, or control unit 5 may be installed outside a housing that houses combustion unit 4 and a hot water supply function unit (not shown).

[0015] The combustion unit 4 is equipped with a plurality of burners that discharge a mixture of, for example, fuel gas G and air, and ignite and burn the discharged mixture. These burners may have the same or different discharge holes for the mixture, for example, in number and size. The combustion unit 4 adjusts the combustion amount by adjusting the number and type of burners that discharge and burn the mixture, and the flow rate of the mixture discharged from the burners. The burners of the combustion section 4 include a first burner section 6-1 and a second burner section 6-2, which are formed by grouping a plurality of burners into sections each having a different number of burners.

[0016] The water heater 2 supplies hot water, cold water, or a heat transfer medium to be heated by exchanging heat with the combustion exhaust gas generated by either or both of the first burner unit 6-1 and the second burner unit 6-2, or supplies heat to heat bathwater or other heat loads. The first burner unit 6-1 and the second burner unit 6-2 are equipped with different numbers of burners. As a result, the first burner unit 6-1 and the second burner unit 6-2 have different combustion capacities, and by burning each burner alone or in combination, they can provide hot water supply capacity that meets hot water demands.

[0017] A flame sensor 8 is installed in the first burner section 6-1 of the combustion section 4. This flame sensor 8 is an example of a means for detecting combustion state information of the flame generated in the burner section 6-1, and a flame rod (FR) is used as the flame sensor 8.

[0018] The control unit 5 is an example of a functional unit that, for example, controls the hot water supply of the hot water supply device 2, controls the combustion of the combustion unit 4, monitors the combustion state of the burner, and controls combustion improvement, and includes a combustion control unit 10 and a combustion adjustment control unit 12. The combustion control unit 10 is an example of a means for controlling the combustion state of the first burner unit 6-1 and the second burner unit 6-2, and monitors the combustion state of the burners, and as a combustion improvement process, instructs the setting of the combustion amount and number of combustion stages of the first burner unit 6-1 and the second burner unit 6-2, as well as changing the combustion mode. The combustion adjustment control unit 12 is an example of a means for monitoring the combustion state of the burner and adjusting the mixture ratio of fuel gas G and air to adjust the combustion state. The control unit 5 receives combustion state information detected by the flame sensor 8 and uses the combustion adjustment control unit 12 to determine the combustion state. The combustion adjustment control unit 12 then outputs a combustion adjustment instruction to the combustion unit 4 based on the determination result.

[0019] <About the number of burner combustion stages> Combustion section 4 of water heater 2 has a number of combustion stages set as burner combustion control to adjust the amount of combustion required in response to a hot water supply request. The number of combustion stages includes, for example, one-stage combustion, in which only the first burner section 6-1 is combusted, two-stage combustion, in which only the second burner section 6-2 is combusted, and three-stage combustion, in which all burners are combusted. The hot water supply capacity of water heater 2 is set by the number of combustion stages of combustion section 4. In normal hot water supply operation, one-stage combustion has a small combustion amount, and a combustion capacity of, for example, 3 to 8. Two-stage combustion has a medium combustion amount, and a combustion capacity of, for example, 6 to 16. Three-stage combustion has a large combustion amount, and a combustion capacity of, for example, 9 to 24.

[0020] <Combustion status monitoring process> In this water heater 2, when the combustion unit 4 is burning in two-stage combustion, as shown in A of FIG. 2, the second combustion mode is switched to, which stops combustion in the first burner unit 6-1, and the combustion state cannot be monitored by the flame sensor 8. If the second combustion mode continues for a long period of time or is intermittent and the set cumulative time exceeds a certain value, the control unit 5 controls combustion in the first combustion mode, which burns at least the first burner unit 6-1. In this first combustion mode, the combustion unit 4, which is set to two-stage combustion, is switched to single-stage combustion, in which only the first burner unit 6-1 burns, as shown in B of FIG. 2, or three-stage combustion, in which the first burner unit 6-1 burns together with the second burner unit 6-2, as shown in C of FIG. 2.

[0021] As means for switching the number of combustion stages and adjusting the combustion amount, water heater 2 is equipped with gas supply pipes 14-1 and 14-2 that supply fuel gas G to first burner unit 6-1 and second burner unit 6-2, and switching valves 16-1 and 16-2 that open or close the flow in these gas supply pipes 14-1 and 14-2. Control unit 5 controls the opening and closing of switching valves 16-1 and 16-2 and the hot water gas proportional valve that adjusts the gas flow rate, thereby adjusting the combustion amount of burner units 6-1 and 6-2 and can meet a wide range of hot water supply requirements.

[0022] <About hot water supply control> Figure 3 shows an example of a processing procedure for hot water supply control. The processing procedure and processing content shown in Figure 3 are only an example, and the present invention is not limited to such a configuration. Furthermore, this hot water supply processing shows an example of a hot water supply program or hot water supply method of the present invention. Water heater 2 sets the combustion amount of combustion unit 4 in response to a hot water supply request (S11). In this combustion amount setting process, the combustion amount is calculated based on, for example, the hot water supply setting temperature, the inlet water temperature, and the inlet water flow rate. Then, control unit 5 sets the number of combustion stages of combustion unit 4 based on the calculated combustion amount. As a monitoring process for the combustion unit 4, the control unit 5 checks the combustion mode from the set number of combustion stages (S12). The control unit 5 determines whether the combustion mode in which the combustion unit 4 cannot detect combustion state information continues for a predetermined time (S13). That is, it determines whether the second combustion mode is continuously set by two-stage combustion. If the combustion mode in which the combustion state information cannot be detected continues (YES in S13), the control unit 5 outputs an instruction to change the combustion mode (S14). For the combustion unit 4 set to two-stage combustion, the control unit 5, for example, increases or decreases the combustion amount to cause the burner to perform one-stage combustion or three-stage combustion. Furthermore, when changing the combustion mode of the combustion unit 4, the control unit 5 may change the combustion range of either or both of the first burner unit 6-1 and the second burner unit 6-2. That is, the control unit 5 may select one-stage combustion or three-stage combustion as the combustion capacity capable of responding to the hot water supply request, and may raise the upper limit of the combustion range of the one-stage combustion or lower the lower limit of the combustion range of the three-stage combustion.

[0023] As combustion adjustment F of the combustion unit 4, the control unit 5 monitors the combustion state of the first burner unit 6-1 based on the combustion state information detected by the flame sensor 8 (S15). The combustion adjustment control unit 12 grasps the combustion state of the entire combustion unit 4 based on the combustion state information of the first burner unit 6-1. Then, the combustion adjustment control unit 12 performs combustion adjustment processing on the combustion unit 4 based on the monitoring results of the combustion state of the combustion unit 4 (S16). This combustion adjustment processing adjusts the combustion amount, mixture ratio, etc. based on conditions such as the combustion amount set in the combustion unit 4. In the combustion adjustment F of the combustion section 4, the monitoring of the combustion state (S15) and the combustion adjustment process (S16) are repeatedly carried out to adjust the burner combustion so as to satisfy the set conditions.

[0024] In addition, when the water heating device 2 enters a one-stage combustion or three-stage combustion state due to a change in the water heating demand during the water heating process, it may, for example, perform a normal combustion process and also read out the combustion state of the combustion section 4 at predetermined intervals and perform a combustion adjustment process.

[0025] <Advantages of the First Embodiment> According to this configuration, one of the following effects can be obtained. (1) Regardless of the hot water supply demand, the combustion state of the combustion unit can be monitored and adjusted, and the combustion state of the combustion unit can be grasped and adjusted, thereby improving the reliability of the hot water supply device. (2) The number of parts can be reduced because the combustion status of the burner can be monitored using flame sensors installed only in some of the burners that are divided into multiple sections. (3) Regardless of the hot water supply demand, the combustion status of the combustion unit is periodically monitored and the status of the combustion unit is improved based on the monitoring results, thereby reducing the environmental load caused by the combustion exhaust generated by the combustion unit. (4) In the combustion state monitoring process, the hot water temperature can be prevented from dropping below or rising above the set temperature, and the hot water temperature can be stabilized.

[0026] Second Embodiment Fig. 4 shows an example of the configuration of a water heater according to a second embodiment. The configuration shown in Fig. 4 is one example, and the present invention is not limited to such a configuration. In Fig. 4, the same parts as in Fig. 1 are assigned the same reference numerals.

[0027] As shown in FIG. 4A, the water heater 2 further includes an air supply fan 18 within the combustion unit 4. The air supply fan 18 is an example of a means for blowing combustion air to the first burner unit 6-1 and the second burner unit 6-2, and is one of the functional units that are adjusted in the combustion adjustment process. That is, the air flow generated by the rotation of the air supply fan 18 affects the amount and concentration of the air-fuel mixture required for combustion. Therefore, in the combustion adjustment process, the amount of air in the air-fuel mixture supplied to the burner is adjusted by increasing or decreasing the rotation speed of the air supply fan 18 based on combustion state information, for example.

[0028] The control unit 5 further includes a storage unit 20 and a timer 22, for example. The storage unit 20 is an example of a means for storing information on the combustion state after the hot water supply process, the monitoring of the combustion unit, and the combustion adjustment process have been performed. Timer 22 is an example of a means for measuring the cumulative combustion time and hot water supply time of first burner unit 6-1 and second burner unit 6-2. The time measurement information by timer 22 may be stored in memory unit 20 together with, for example, combustion state information. 4B, the storage unit 20 stores combustion mode setting information 24, combustion state information 26 detected by the flame sensor 8, combustion adjustment information 28, cumulative time information 30, and the like. The combustion mode setting information 24 is instruction information for causing the combustion unit 4, which is operating in the second combustion mode in which the combustion state cannot be monitored, to change to the first combustion mode when a combustion monitoring condition is met. This instruction information includes, for example, an increase or decrease in the set temperature in response to a hot water supply request, an adjustment of the amount of water supplied, and other methods. The combustion state information 26 is an example of information detected by the flame sensor 8. The combustion adjustment information 28 is an example of the adjustment process content for the burner and the air supply fan 18 based on the detected combustion state information. Accumulated time information 30 is an example of information on the accumulated time that at least water heater 2 continues in two-stage combustion (second combustion mode), and may also include the total hot water supply operation time and the like.

[0029] <Hot water supply operation processing> Fig. 5 shows an example of hot water supply operation processing. The processing procedure and processing contents shown in Fig. 5 are one example, and the present invention is not limited to such a configuration. Furthermore, this hot water supply operation control shows one example of a hot water supply program or hot water supply method of the present invention. Control unit 5 of water heater 2 checks the combustion mode from the set number of combustion stages as a process for monitoring combustion unit 4 (S21). The control unit 5 determines whether the combustion unit 4 is in the second combustion mode, in which combustion state information cannot be detected (S22). That is, it determines whether the second combustion mode is set by two-stage combustion. If the second combustion mode is not set (NO in S22), normal hot water supply processing is executed (S23). If combustion is occurring in the second combustion mode (YES in S22), the timer 22 is used to measure the cumulative time TA in the second combustion mode (S24). The cumulative time TA measured by the timer 22 is stored in the memory unit 20 as cumulative time information 30.

[0030] The control unit 5 then monitors whether the combustion mode has been changed (S25), and if it has been changed (YES in S25), the process proceeds to normal hot water supply processing (S23). At this time, the timer 22 is reset. If the second combustion mode continues (NO in S25) and the accumulated time TA exceeds a predetermined time TX, such as 30 hours (YES in S26), the control unit 5 proceeds to combustion mode change processing (S27). The control unit 5 reads, for example, the combustion mode setting information 24, and changes a burner that is set to two-stage combustion to one-stage combustion or three-stage combustion. This combustion mode change control may be performed, for example, when the predetermined time TX has elapsed, or when the next hot water supply operation starts after the current hot water supply operation has ended.

[0031] Control unit 5 acquires combustion state information detected by flame sensor 8 as combustion adjustment F of combustion unit 4, stores it in memory unit 20 as combustion state information 26, and monitors the combustion state of first burner unit 6-1 (S28). Combustion adjustment control unit 12 grasps the overall combustion state of combustion unit 4 from the combustion state information of first burner unit 6-1. Then, the combustion adjustment control unit 12 reads out, for example, the combustion adjustment information 28 and adjusts the functional units such as the air supply fan 18 (S29). In the combustion adjustment F of this combustion section 4, the monitoring of the combustion state (S28) and the combustion adjustment process (S29) are repeatedly carried out to adjust the burner combustion so as to satisfy the set conditions.

[0032] When water heater 2 is operating as a normal hot water supply process in the first combustion mode in which the combustion state can be monitored, combustion adjustment F may be performed, for example, every fixed cumulative combustion time.

[0033] <Advantages of the second embodiment> According to this configuration, one of the following effects can be obtained. (1) Even when supplying hot water to a hot water load with little fluctuation in hot water demand, the combustion state can be monitored periodically and combustion adjustment processing can be performed, thereby improving the reliability and safety of the water heater. (2) By using timer 22 to monitor the accumulated time TA during which the flame sensor 8 is unable to detect combustion state information, even when hot water is supplied intermittently, the combustion state is monitored and combustion adjustment processing is initiated depending on the length of time the burner is in use, thereby improving the safety of the water heating device 2. (3) In a burner that adjusts combustion capacity by combining multiple divided burners, the combustion status can be monitored and combustion adjustment processing can be performed without installing flame sensors on all burners, which reduces the number of parts and contributes to cost savings. [Example]

[0034] <Hot water supply device 40> Fig. 6 shows a water heater 40 according to the first embodiment. In Fig. 6, the same parts as those in Figs. 1 and 4 are denoted by the same reference numerals. 6, gas supply pipes 14-1 and 14-2 that supply fuel gas G, a water supply pipe 42 that takes in water W, and a hot water supply pipe 44 that dispenses heated hot water HW are connected to water heater 40. Water heater 40 burns fuel gas G taken in through gas supply pipes 14-1 and 14-2 to generate combustion exhaust. Water heater 40 then exchanges heat between the low-temperature water W taken in from water supply pipe 42 and the combustion exhaust to generate hot water HW, which is then dispensed from hot water supply pipe 44.

[0035] In this water heater 40, for example, a burner 48 and heat exchangers 50, 52 are installed in a combustion chamber 46. Combustion air is drawn into the combustion chamber 46 by an air supply fan 54. Fuel gas G is supplied to the burner 48 from gas supply pipes 14-1, 14-2. These gas supply pipes 14-1, 14-2 are equipped with a main gas solenoid valve 56 that allows or blocks the passage of fuel gas G and a hot water gas proportional valve 58 that controls the amount of gas flowing into the burner 48. The burner 48 is equipped with multiple burner sections 6-1, 6-2, and the supply of fuel gas G to each burner section 6-1, 6-2 is switched by switching valves 16-1, 16-2. Combustion exhaust gas produced by combustion in the burner 48 is discharged to the outside of the combustion chamber 46 from an exhaust port 55 of the combustion chamber 46. An ignition plug 60 and a flame rod 62 are installed in the combustion chamber 46 near the gas ejection holes of the burner section 6-1. The ignition plug 60 is connected to an igniter 64 installed, for example, outside the combustion chamber 46, and ignites the burner section 6-1. After the burner section 6-1 ignites, the burner 48 ignites the burner section 6-2 using the flame of the burner section 6-1. The flame rod 62 is an example of a flame sensor used to monitor the combustion state of the burner section 6-1 and to adjust the combustion. Furthermore, the combustion chamber 46 may be provided with a flame rod that detects only the ignition state of the burner sections 6-1 and 6-2, for example.

[0036] The heat exchanger 50 is installed downstream of the exhaust path through which the combustion exhaust flows within the combustion chamber 46, and is an example of a secondary heat exchanger that primarily recovers the latent heat of the combustion exhaust by exchanging heat with low-temperature feedwater W. The heat exchanger 52 is installed upstream of the exhaust path and is an example of a primary heat exchanger that mainly recovers sensible heat from the combustion exhaust by exchanging heat with the supply water W that has been heat exchanged in the heat exchanger 50.

[0037] The water supply pipe 42 through which the water supply W flows is equipped with, for example, a temperature sensor 68, a water volume sensor 70, and a mixed water control valve 72. The temperature sensor 68 detects the water supply temperature. The water volume sensor 70 detects the volume of water supply W corresponding to hot water supply. The mixed water control valve 72 adjusts the supply of water supply W flowing through the bypass pipe 74 and controls the amount of water supply W mixed with the hot water HW. Heat exchangers 50 and 52 are connected in series, and hot water HW from heat exchanger 52 flows into an outlet pipe 76. A temperature sensor 78 and a water control valve 80 are installed in this outlet pipe 76. The temperature sensor 78 detects the outlet temperature of the hot water HW flowing on the outlet side of heat exchanger 52. The water control valve 80 regulates whether or not hot water is supplied by opening and closing, but also serves as a mixing chamber that mixes the supply water W and hot water HW through the bypass pipe 74. A temperature sensor 82 installed in the hot water supply pipe 44 is a means for detecting the temperature of the hot water HW discharged from the hot water supply device 40, and detects the temperature of the hot water HW mixed with the supply water W by the water control valve 80. Water heater 40 controls the intake of water W and the discharge of hot water HW by opening and closing water control valve 80. That is, when water heater 40 opens water control valve 80 to allow water W to flow in, water pressure from the water source causes water W to flow into water supply pipe 42.

[0038] Water heater 40 also includes control device 90, which sets the amount of hot water supplied and the amount of combustion according to the hot water supply demand, monitors the combustion state of burner units 6-1 and 6-2, and controls the combustion adjustment process. For example, when control device 90 detects the amount of water supplied by water volume sensor 70, it automatically starts combustion control according to the flow rate.

[0039] Furthermore, combustion chamber 46 is provided with a drain receiver 66 that collects drain D generated by heat exchange in heat exchanger 50. Drain D is led from drain receiver 66 to a drain tank through a drain pipe. When the drain D in this drain tank exceeds a predetermined level, it is discharged from the drain tank through a drain pipe to the outside of water heater 40.

[0040] <Regarding the control device 90> FIG. 7 shows an example of the configuration of the control device. This control device 90 is composed of a computer and includes, for example, as shown in Figure 7, a processor 92, a memory unit 94, a display unit 96, a timer 22, a communication unit 98 that communicates with an external remote control device 100, and an input / output unit (I / O) 102. Processor 92 executes programs stored in memory unit 94, for example, and performs information processing such as hot water supply control of water heater 40, combustion control of burner units 6-1 and 6-2, monitoring of the combustion state, and combustion adjustment processing. The memory unit 94 is a storage means for storing programs such as hot water supply control and combustion state monitoring processing, as well as detected combustion state information, and is equipped with memory elements such as ROM (Read-Only Memory), RAM (Random-Access Memory), and EEPROM (Electrically Erasable Programmable Read-Only Memory). The display unit 96 is an example of a means for displaying set temperature information, which is a hot water supply request, as well as displaying the details of ongoing processes such as combustion state monitoring and combustion adjustment processes, and notification information, etc. The display unit 96 may be, for example, an LCD (Liquid Crystal Display). The timer 22 is an example of a means for timing the combustion time in the second combustion mode in the combustion state monitoring process. This timer 22 may be, for example, a hardware clock mounted on a control board, or may be a software clock that is timed by a control program such as an OS (Operating System). Under the control of processor 92, communication unit 98 communicates with remote control device 100 to exchange information necessary for hot water supply control, the results of monitoring the burner combustion state, and other information such as burner combustion improvement processing.

[0041] I / O 102 is an interface that connects with each functional unit of water heater 40. In control device 90, detection signals are taken in via I / O 102 from sensors such as temperature sensors 68, 78, and 82 and water volume sensor 70, and control outputs are obtained from I / O 102 to mixed water control valve 72, water control valve 80, and combustion system functional units such as main gas solenoid valve 56, hot water gas proportional valve 58, switching valves 16-1 and 16-2, flame rod 62, igniter 64, and air supply fan 54.

[0042] <Monitoring the combustion state> FIG. 8 shows an example of the combustion state monitoring process. The flame rod 62 is an example of a flame sensor that detects combustion state information that changes depending on the state of a burning flame by contacting it with the flame. "FRA" in A of Figure 8, which shows the shape of the burning flame, is the part of the flame rod 62 that is in contact with the flame. The flame rod 62 detects the flame current value as combustion state information that changes depending on the height of the flame. FIG. 8B shows the relationship between the location of the flame during combustion and the current value. The detected flame current value is greatest near the center of the flame (PB), and decreases at PA, which is closer to the burner, and at PC, which is closer to the tip of the flame. In other words, the current value decreases with increasing distance from the center of the flame. Since the flame rod 62 is fixed in position, the current value can be used to monitor changes in the shape of the flame according to the combustion state of the burner. In other words, as the flame becomes smaller and the PB approaches the FRA, the current value IA increases. As the flame becomes larger and the PB moves away from the FRA, the current value decreases. The control device 90 utilizes the relationship between the detected current value and the change in the shape of the flame to improve combustion in the burner 48. In this combustion improvement process, for example, the rotation speed of the air supply fan 54 that sends air to the burner 48 is adjusted. The control device 90 increases the rotation speed of the air supply fan 54 when the current value detected using, for example, the frame rod 62 is greater than the ideal value, and decreases the rotation speed of the air supply fan 54 when the current value is smaller than the ideal value.

[0043] The ideal flame shape changes depending on the amount of combustion (the number of combustion stages and the current value of the hot water gas proportional valve 58), and the ideal value of the current detected by the flame rod 62 also changes. Therefore, by preparing ideal current value data in advance for the number of combustion stages and the current value of the hot water gas proportional valve 58, and detecting the current current value relative to the ideal value and correcting the fan rotation speed, the flame shape can be controlled to the ideal state.

[0044] <Regarding the timing of monitoring process execution> Fig. 9 shows an example of the timing at which the combustion state monitoring process is executed. The process contents and process timing shown in Fig. 9 are just an example. When hot water supply processing using two-stage combustion continues intermittently, as shown in A of Fig. 9, control device 90 uses timer 22 to measure each combustion time t1, t2, ..., tn. Water heating device 40 accumulates and stores the accumulated combustion times in memory unit 94, and when accumulated time TA exceeds a predetermined time TX, for example, 30 hours, a combustion status monitoring processing mode is set. Then, at the start of the next hot water supply operation, water heating device 40 performs combustion in the first combustion mode (single-stage combustion or three-stage combustion) for a certain time TC, for example, 10 seconds, regardless of the hot water supply request, as a combustion status monitoring processing, and then performs combustion with the number of stages according to the hot water supply request. In addition, the control device 90 may measure the elapsed time TB until the start of the next hot water supply operation after the accumulated time TA exceeds a predetermined time TX, and set the combustion capacity for the next hot water supply operation according to the length of this elapsed time TB.

[0045] Furthermore, as shown in Fig. 9B, for example, if the hot water supply demand fluctuates after hot water supply processing using two-stage combustion has continued and burner 48 switches to single-stage combustion, control device 90 resets accumulated time TA stored in memory unit 94. Then, the next time two-stage combustion is performed, control device 90 measures the new combustion time of two-stage combustion and stores it as accumulated time TA. Furthermore, when burner 48 switches to single-stage combustion, water heating device 40 can monitor the combustion state using flame rod 62 and adjust combustion according to the combustion state.

[0046] <Hot water supply operation processing> Fig. 10 shows an example of hot water supply operation processing. The processing procedure and processing contents shown in Fig. 10 are one example, and the present invention is not limited to such a configuration. Furthermore, this hot water supply control shows an example of a hot water supply program or hot water supply method of the present invention. The control device 90 monitors the combustion unit 4 and monitors that the hot water supply process is being performed in the second combustion mode. Steps S31 to S34 may be similar to steps S21 to S23 and S26 in FIG.

[0047] After cumulative time TA exceeds predetermined time TX, water heating apparatus 40 performs hot water supply processing in accordance with the ongoing hot water supply request, and ends the hot water supply processing when the hot water supply request disappears (S35). Then, when the next hot water supply request occurs (S36), water heating apparatus 40 performs one-stage combustion of burner 48 so as to enter the first combustion mode (S37) regardless of the content of the hot water supply request, and monitors the combustion state (S38) and performs combustion adjustment processing (S39).

[0048] <Combustion improvement treatment> An example of combustion improvement processing is shown in Fig. 11. The processing contents and processing procedures shown in Fig. 11 are merely an example, and the present invention is not limited to such a configuration. This combustion improvement process is an example of an adjustment process for the combustion section 4, and adjusts the amount of air supply based on the results of monitoring the combustion state, for example. Control device 90 acquires the flame current value detected by flame rod 62 (S51), and acquires an ideal value for the flame current value based on the combustion conditions of combustion unit 4 (S52). This ideal value for the flame current value is information on the ideal amount of air supplied by air supply fan 54 or its rotation speed, and may be stored in memory unit 94 of water heating apparatus 40, or may be acquired from an external database via communication means. When the controller 90 determines that the flame current value is less than the ideal value (YES in S53), it corrects the rotation speed of the air supply fan 54 to the negative side (S54). If the flame current value is not less than the ideal value (NO in S53), the controller 90 determines whether the flame current value is greater than the ideal value (S55). If the flame current value is greater than the ideal value (YES in S55), the controller 90 corrects the rotation speed of the air supply fan 54 to the positive side (S56). Furthermore, if the flame current value is not greater than the ideal value (NO in S55), the control device 90 determines that the combustion state of the burner 48 is ideal, and maintains the rotation speed of the air supply fan 54. The amount of adjustment of the rotation speed of air supply fan 54 is set depending on the type and size of water heater 40, the number of hot water that can be supplied, as well as other conditions such as safety regulations for water heaters.

[0049] <Effects of Example 1> According to the first embodiment, any of the following effects can be obtained. (1) Even if the hot water supply operation continues in which only the second burner section 6-2, in which the flame rod 62 is not installed, is combusted, the combustion state can be monitored and combustion adjustment processing can be performed. (2) Regardless of the combustion mode, the combustion state of the burner 48 can be monitored and adjusted, thereby ensuring the safety and improving the reliability of the water heater. (3) In the combustion section 4 divided into a plurality of burner sections 6-1, 6-2, there is no need to provide a flame rod 62 for each of the burner sections 6-1, 6-2, and costs can be reduced by reducing the number of parts. (4) The combustion state can be monitored and the combustion section can be adjusted periodically, which can prevent incomplete combustion in the burner 48 or combustion with an excess of fuel gas, thereby reducing the environmental load. (5) By burning the burner 48 in the first combustion mode and monitoring and adjusting the combustion state, it is possible to avoid high-temperature hot water HW being discharged due to a combustion capacity that exceeds the hot water supply demand, thereby increasing the safety of users of the hot water supply device. (6) By monitoring and adjusting the combustion state by causing burner 48 to burn in one-stage or three-stage combustion, the two-stage combustion portion can be covered, and the discharge of low-temperature hot water HW or high-temperature hot water HW can be avoided with a combustion capacity that satisfies the hot water supply demand, thereby avoiding temperature changes during hot water supply, thereby improving convenience for users of water heating device 40. [Example]

[0050] <Hot water heater 110> Fig. 12 shows a water heater 110 according to Example 2. In Fig. 12, the same parts as those in Figs. 1 and 4 are denoted by the same reference numerals. In this water heater 110, when only second burner unit 6-2, which does not have flame rod 62, is burning, the combustion state is monitored and the number of burners that can be burned is increased when the accumulated combustion time TA of the burners exceeds a predetermined time TX, as an adjustment process for combustion unit 4. As shown in FIG. 12 , for example, water heater 110 includes combustion unit 4 and control unit 5, and has combustion mode switching table 112 stored in memory unit 20.

[0051] <Combustion mode switching table 112> This combustion mode switching table 112 is an example of limit threshold information when burner 48 is forced to switch from two-stage combustion to three-stage combustion. The hot water supply capacity of water heater 110 is determined by the thermal energy obtained by combustion of burner 48. For example, burner 48 has a hot water supply capacity of 6 to 16 (number) when in two-stage combustion. One (number) of hot water supply capacity is the amount of combustion required to raise the temperature of 1 liter of water by 25 degrees Celsius in one minute, and the combustion rate per hour is 1 (number) = 1,500 kilocalories / h. Increasing the hot water supply setting temperature to increase the number of combustion stages of burner 48 during combustion reduces the flow rate of hot water that can be supplied. Burner 48 of water heater 110 is prescribed with an ignition flow rate that indicates a minimum flow rate to prevent, for example, excessive combustion and boiling of water in heat exchangers 50 and 52. Therefore, in combustion unit 4, if the set temperature is increased too much, the flow rate will be lower than the ignition flow rate that causes combustion in both first burner unit 6-1 and second burner unit 6-2, and there is a risk that the number of combustion stages cannot be increased.

[0052] Therefore, as shown in FIG. 13, for example, combustion mode switching table 112 stores the flow rates at which hot water can be supplied when the set temperature (Tβ1, Tβ2, . . . , Tβ18) is set for the inlet water temperature (Tα1, Tα2, . . . , Tα11) in the combustion amount during two-stage combustion. Combustion mode switching table 112 also stores a limit threshold P that indicates the boundary between the hot water supply flow rate LX at which switching to three-stage combustion is possible and the hot water supply flow rate LY at which switching is not possible. This limit threshold P varies depending on, for example, the specified value of the ignition flow rate of water heater 110. In other words, when the ignition flow rate is small, switching to three-stage combustion is possible even at a low flow rate, whereas when the ignition flow rate is large, switching to three-stage combustion is not possible, narrowing the range in which the set temperature can be increased. Water heater 110 changes the number of combustion stages while utilizing limit threshold P of combustion mode switching table 112 in the combustion state monitoring and combustion adjustment process when two-stage combustion is continuing.

[0053] <Hot water supply operation processing> Fig. 14 shows an example of hot water supply operation processing. The processing procedure and processing contents shown in Fig. 14 are one example, and the present invention is not limited to such a configuration. Furthermore, this hot water supply operation processing shows one example of the hot water supply program or hot water supply method of the present invention. Water heating apparatus 110 performs a process of monitoring combustion unit 4, and monitors that the water heating process is being performed in the second combustion mode. Steps S61 to S64 may be the same processes as steps S21 to S23 and step S26 in FIG.

[0054] Next, as combustion adjustment F, which includes changing the number of combustion stages and monitoring the combustion state, water heater 110 reads combustion mode switching table 112 from memory unit 20 (S65), reads limit threshold P at which the number of combustion stages can be increased relative to the inlet water temperature, and changes the hot water temperature (S66). The set temperature may be selected within a range where the flow rate is greater than limit threshold P and where burner 48 performs three-stage combustion. After three-stage combustion is initiated, water heater 110 monitors the combustion state using the detection information of flame rod 62 (S67), and performs combustion adjustment processing based on the monitoring results (S68).

[0055] When water heating apparatus 110 increases the number of combustion stages during hot water supply, for example, control apparatus 90 or remote control apparatus 100 may display a warning about temperature changes on a display unit or may notify the warning by voice. Furthermore, water heater 110 may forcibly increase the amount of water supplied from the water supply pipe when, for example, the set temperature is changed and ignition of three-stage combustion is confirmed.

[0056] <Effects of Example 2> According to the second embodiment, one of the following effects can be obtained. (1) The combustion state of the burner can be monitored periodically and improvements can be made to the combustion section, thereby improving the reliability and safety of the water heater. (2) Even when the burner is operated at a high combustion rate in response to a hot water supply request, the combustion state of the burner can be monitored without reducing the combustion rate. (3) In the combustion state monitoring process, the hot water temperature can be prevented from dropping. [Example]

[0057] <Hot water treatment> Fig. 15 shows an example of a hot water supply process according to Example 3. The process procedure and process contents shown in Fig. 15 are merely an example, and the present invention is not limited to such a configuration. In this hot water supply process, when the hot water supply operation continues in the second combustion mode, the combustion mode of the combustion unit 4 is changed, and the range of the combustion capacity of the combustion unit 4 is changed. When starting a hot water supply operation or receiving a hot water supply request, water heater 40 prepares for operation (initializes) (S71) and starts supplying hot water. Then, control device 90 monitors whether burner 48 is burning (S72), and if burner 48 is burning (YES in S72), determines whether there is a request to confirm the combustion state (S73). When there is a request to confirm the combustion state, for example, as a self-diagnosis process of the water heater, as described above, it may determine whether burner combustion is set to continue in the second combustion mode.

[0058] If there is a request to confirm the combustion state (YES in S73), the combustion mode of the burner 48 is changed to the first combustion mode. At this time, the control device 90 changes, for example, the range of combustion capacity set in the combustion unit 4 (S74). At this time, for example, the range of combustion capacity for single-stage combustion is changed to No. 3 to No. 9, and the range of combustion capacity for three-stage combustion is changed to No. 8 to No. 24. This change in the range of combustion capacity may be, for example, a change to only one of the combustion capacity for single-stage combustion or the combustion capacity for three-stage combustion, or a change to both. After adjusting the range of combustion capacity, the control device 90 monitors the combustion state for, for example, 10 seconds (YES in S75), and determines whether combustion improvement is necessary (S76). If the control device 90 determines that combustion improvement is necessary (YES in S76), it executes combustion improvement processing (S77) and performs re-monitoring processing of the combustion state for a combustion state confirmation time of, for example, 10 seconds, to determine whether further combustion improvement is necessary (S78). When the control device 90 determines that combustion improvement is not necessary (NO in S76), it cancels the combustion state confirmation process (S79).

[0059] Furthermore, if a request to check the combustion state has not been issued (NO in S73), the control device 90 sets the combustion range for normal hot water supply operation for the combustion unit 4 (S80). The combustion ranges at this time may be, for example, a range of combustion capacity for single-stage combustion from No. 3 to No. 8, a range of combustion capacity for two-stage combustion from No. 6 to No. 16, and a range of combustion capacity for three-stage combustion from No. 9 to No. 24. If the number of the hot water supply request is for the first combustion mode, which is single-stage combustion or three-stage combustion (YES in S81), the control device 90 performs a combustion state monitoring process for, for example, 10 seconds (YES in S82), and resets the timer 22 to remeasure the time during which the combustion state self-diagnosis was not performed, i.e., the accumulated time TA (S83). If the number of the hot water supply request is not the first combustion mode, which is one-stage combustion or three-stage combustion (NO in S81), that is, if the combustion state cannot be monitored due to two-stage combustion, the control device 90 measures the time during which self-diagnosis of the combustion state is not performed using the timer 22 (S84).

[0060] Furthermore, the control device 90 generates a combustion state confirmation request (S87) if combustion is not in progress (NO in S72), if a predetermined time TX, for example 30 hours, has elapsed without self-diagnosis of the combustion state (YES in S85), or if a hot water supply request has not occurred and combustion is stopped (YES in S86).

[0061] <Effects of Example 3> According to the third embodiment, one of the following effects can be obtained. (1) By changing the range of the combustion capacity of the combustion unit 4, hot water can be supplied in response to a hot water supply request even when the combustion state monitoring process and the combustion improvement process are being executed. (2) The combustion state of the burner can be monitored periodically and improvements can be made to the combustion section, thereby improving the reliability and safety of the water heater. (3) Even when the burner is operated at a high combustion rate in response to a hot water supply request, the combustion state of the burner can be monitored without reducing the combustion rate. (4) In the combustion state monitoring process, the hot water temperature can be prevented from dropping below or rising above the set temperature.

[0062] Modifications of the above-described embodiments and examples are listed below.

[0063] (1) In the second embodiment, the hot water temperature is increased to increase the number of combustion stages. However, this is not limiting. For example, hot water heater 110 may control the hot water temperature to three-stage combustion by forcibly increasing the amount of water supplied from the water supply pipe while maintaining the set temperature during two-stage combustion, thereby increasing the hot water supply rating. In this case, hot water heater 110 may adjust the opening of the water supply valve or mixed water control valve 72, for example.

[0064] (2) In the above embodiment and example, the combustion state is monitored and combustion adjustment processing is performed by changing the combustion amount when the cumulative time of two-stage combustion has been reached or at the start of the next hot water supply operation. However, this is not limited to this. The water heating device may, for example, set the timing for changing the number of combustion stages depending on the hot water supply load. The control unit 5 of the water heating device may determine the type of hot water supply load using, for example, the hot water supply amount, flow rate fluctuation information during hot water supply, ON / OFF timing switching of hot water supply, hot water supply set temperature, and other hot water supply instruction information. Then, for example, when a constant amount of hot water is required for a long period of time, the control unit 5 may determine that the request is for hot water supply to a bathtub or a common pipe that serves multiple hot water supply loads. Alternatively, when the flow rate or hot water supply ON / OFF is repeatedly changed intermittently, the control unit 5 may determine that the request is for hot water supply from a shower or hot water outlet. The water heater may change the number of combustion stages during hot water supply and set to the first combustion mode, for example, when supplying hot water to a facility, since fluctuations in flow rate and hot water temperature during hot water supply are less likely to have an effect. When supplying hot water to a shower or hot water outlet that the user may directly touch, the water heater may set to the first combustion mode the next time hot water supply operation begins.

[0065] As explained above, the most preferred embodiment of the present invention has been described. However, the present invention is not limited to the above description. Various modifications and changes are possible for those skilled in the art based on the gist of the invention as set forth in the claims or disclosed in the detailed description. It goes without saying that such modifications and changes are included within the scope of the present invention. [Industrial Applicability]

[0066] In the water heating device of the present invention, if the water heating process continues in a combustion mode in which the combustion state of the burner cannot be detected, the combustion mode of the combustion section is changed to monitor the combustion state and perform adjustment processing on the combustion section, which is useful in that it is possible to maintain and manage the combustion state of the burner at an appropriate state while minimizing the impact on the water heating process. [Explanation of symbols]

[0067] 2, 40, 110 Hot water supply equipment 4 Combustion section 5. Control section 6-1 First burner section 6-2 Second burner section 8 Flame Sensor 10 Combustion control unit 12 Combustion adjustment control unit 14-1, 14-2 Gas supply pipes 16-1, 16-2 Switching valve 18, 54 Intake fan 20 Memory section 22 Timer 24 Combustion mode setting information 26 Combustion status information 28 Combustion Adjustment Information 30 Accumulated time information 42 Water supply pipe 44 Hot Water Pipe 46 Combustion chamber 48 Burner 50, 52 heat exchanger 55 exhaust port 56 Main gas solenoid valve 58 Hot water gas proportional valve 60 Spark plug 62 Frame Rod 64 Igniter 66 Drain pan 68, 78, 82 Temperature sensors 70 Water level sensor 72 Mixed water control valve 74 Bypass pipe 76 Outlet pipe 80 Water control valve 90 Control device 92 processors 94 Memory section 96 Display section 98 Communications Department 112 Combustion mode switching table

Claims

1. a first burner section for burning in a first combustion mode; a second burner unit that burns at a combustion amount exceeding that of the first burner unit in the first combustion mode and the second combustion mode; a flame sensor installed in the first burner unit to detect a flame; a control unit that sets a combustion amount according to a hot water supply request, selects the first combustion mode using only the first burner unit, the first combustion mode using a combination of the first burner unit and the second burner unit, or the second combustion mode, and when the cumulative time of the second combustion mode during combustion reaches a certain time or more, performs hot water supply processing in accordance with the ongoing hot water supply request, terminates the hot water supply processing when the hot water supply request disappears, and after this termination, when a hot water supply request occurs, causes the first burner unit to combust so that the first combustion mode is selected regardless of the content of the hot water supply request; wherein the control unit acquires a flame current value from the flame sensor and increases or decreases the rotation speed of the air supply fan based on the result of comparing the flame current value with an ideal value.

2. The water heater device of claim 1, characterized in that the control unit uses a combustion mode switching table to adjust combustion, including changing the number of combustion stages of the first burner unit or the second burner unit or monitoring the combustion state, to change the hot water temperature based on the limit value to which the number of combustion stages can be increased, and selects a hot water temperature that results in three-stage combustion within a range in which the hot water supply flow rate is greater than the limit threshold value.

3. A program for controlling a water heater using a computer, a function of firing the first burner section in a first combustion mode; a function of causing the second burner unit to combust at a combustion amount exceeding that of the first burner unit in the first combustion mode and the second combustion mode; a function of detecting a flame by a flame sensor installed in the first burner unit; a function of setting a combustion amount according to a hot water supply request, selecting the first combustion mode by combustion by the first burner unit alone, the first combustion mode by combustion by a combination of the first burner unit and the second burner unit, or the second combustion mode, and when the cumulative time of the second combustion mode during combustion reaches a certain time or more, performing hot water supply processing in accordance with the ongoing hot water supply request, terminating the hot water supply processing when the hot water supply request disappears, and after this termination, when a hot water supply request occurs, causing the first burner unit to combust so that the first combustion mode is selected regardless of the content of the hot water supply request; a function of acquiring a flame current value from the flame sensor and increasing or decreasing the rotation speed of the air intake fan based on the result of comparing this flame current value with an ideal value; A program for causing the computer to execute the above.

4. firing the first burner section in a first combustion mode; firing a second burner section in the first combustion mode and in the second combustion mode at a combustion amount greater than that of the first burner section; detecting a flame with a flame sensor installed in the first burner section; a step of setting a combustion amount according to a hot water supply request, selecting the first combustion mode by combustion by the first burner unit alone, the first combustion mode by combustion by a combination of the first burner unit and the second burner unit, or the second combustion mode, and when the cumulative time of the second combustion mode during combustion reaches a certain time or more, performing hot water supply processing in accordance with the ongoing hot water supply request, terminating the hot water supply processing when the hot water supply request disappears, and after this termination, when a hot water supply request occurs, causing the first burner unit to combust so that the first combustion mode is selected regardless of the content of the hot water supply request; acquiring a flame current value from the flame sensor, and increasing or decreasing the rotation speed of the air supply fan based on a result of comparing the flame current value with an ideal value; A method for controlling a water heater, comprising:

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