Hot water supply heater

Abstract

To suppress consumption of energy for preventing freezing.SOLUTION: A control device 70 of a hot water supply heater 1 executes first operation so that a selector valve is in a first state and a heating circulation pump 37 is driven without combusting heating burners 33A, 33B when a temperature detected by any of temperature sensors is equal to or lower than a first threshold TH1. After the first operation, the control device 70 executes second operation so that the heating burners 33A, 33B are not combusted when the temperature detected by any of the temperature sensors is equal to or higher than a second threshold TH2, and so that the heating burner 33A is combusted and the heating circulation pump 37 is driven when the detected temperature is lower than the second threshold TH2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a water heater and a heating device.

Background Art

[0002] Patent Document 1 describes a hot water heating device. This hot water heating device burns a burner, heats the hot water in the heating circulation circuit with a heat exchanger, and circulates the hot water in the heating circulation circuit by a heating pump. The hot water control device includes an outside air temperature sensor and a water temperature sensor provided in the heating forward passage for detecting the temperature of the hot water in the heating circulation circuit. When the temperature of the outside air detected by the outside air temperature sensor is 3°C or lower, after driving the heating pump without burning the burner, based on the heating time and the target supply temperature determined according to the temperature detected by the water temperature sensor, the burner is burned and the heating pump is driven to heat and circulate the hot water in the heating circulation circuit to prevent freezing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the configuration of the above Patent Document 1, in order to prevent the freezing of the heat medium, it is necessary to burn the burner and heat the hot water in the heating circulation circuit with a heat exchanger based on the heating time and the target supply temperature determined according to the detected water temperature of the water temperature sensor provided in the heating forward passage. Therefore, although the possibility of freezing is not necessarily high, the burner is burned according to the detected temperature of the water temperature sensor, and there is a problem that energy consumption tends to increase.

[0005] One of the objects of the present disclosure is to propose a technique for suppressing energy consumption for preventing freezing.

Means for Solving the Problem

[0006] One of the disclosed water heaters and heaters supplies the heat medium to a heat dissipation terminal having a terminal flow path through which the heat medium flows and configured to dissipate the heat of the heat medium flowing through the terminal flow path, and is a water heater and heater that controls a switching valve that switches between a first state that permits the supply of the heat medium to the terminal flow path and a second state that shuts off the supply. The water heater and heater includes a hot water supply circuit that heats water supplied from outside the water heater and heater to supply hot water, a burner unit having a burner that burns gas, a heat exchanger that is heated by the exhaust gas generated by the burner, a heat medium circulation path that is a path for circulating the heat medium together with the terminal flow path and through which the heat medium flows through the heat exchanger, and a pump that causes the heat medium to flow in the heat medium circulation path. The heat exchanger heats the heat medium, and a heating circuit supplies the heat medium to the terminal flow path via the heat medium circulation path. One or more temperature sensors that detect the temperature inside the water heater and heater or the outside air temperature, and a control unit that controls the operations of the burner and the pump. When the temperature detected by any of the temperature sensors is equal to or lower than a first threshold value, the control unit performs a first operation in which the switching valve is set to the first state and the pump is driven without burning the burner. After the first operation, when the temperatures detected by all of the one or more temperature sensors are equal to or higher than a second threshold value, the burner is not burned. When the temperature detected by any of the temperature sensors is lower than the second threshold value, a second operation is performed in which the burner is burned and the pump is driven. The control unit is provided with: When the temperature detected by any of the temperature sensors is equal to or lower than a first threshold value, the switching valve is set to the first state and the pump is driven without burning the burner. After the first operation, when the temperatures detected by all of the one or more temperature sensors are equal to or higher than a second threshold value, the burner is not burned. When the temperature detected by any of the temperature sensors is lower than the second threshold value, a second operation is performed in which the burner is burned and the pump is driven.

Advantages of the Invention

[0007] According to the technology according to the present disclosure, it is possible to suppress the consumption of energy for preventing freezing.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Each of the following [1] to [6] is an example of a hot water heater or a hot water heating system included in the present disclosure. [1] A hot water heater that supplies a heat medium to a heat dissipation terminal configured to have a terminal flow path through which the heat medium flows and to dissipate the heat of the heat medium flowing through the terminal flow path, and controls a switching valve that switches between a first state that permits the supply of the heat medium to the terminal flow path and a second state that shuts off the supply, a hot water supply circuit that heats water supplied from outside the hot water heater to supply hot water, a burner unit having a burner that burns gas, a heat exchanger heated by the exhaust gas generated by the burner, a heat medium circulation path that is a path for circulating the heat medium together with the terminal flow path and through which the heat medium flows through the heat exchanger, and a pump that causes the heat medium to flow in the heat medium circulation path, and includes a heating circuit that heats the heat medium by the heat exchanger and supplies the heat medium to the terminal flow path via the heat medium circulation path, one or more temperature sensors that detect the temperature inside the hot water heater or the outside air temperature, a control unit that controls the operations of the burner and the pump, and is provided with, the control unit, when the temperature detected by any of the temperature sensors becomes equal to or lower than a first threshold value, performs a first operation of setting the switching valve to the first state and driving the pump without burning the burner. After the first operation, if the temperatures detected by all of the one or more temperature sensors are equal to or higher than a second threshold value, the burner is not burned, and if the temperature detected by any of the temperature sensors is less than the second threshold value, a second operation is performed to burn the burner and drive the pump. A hot water heater.

[0010] In the hot water heater according to [1] above, when the temperature detected by any of the temperature sensors becomes equal to or lower than a first threshold value, a first operation of driving the pump is performed. Therefore, due to the driving of the pump during the first operation, the heat medium circulates in the heat medium circulation path. Before the first operation, it is highly likely that a relatively high-temperature heat medium exceeding the first threshold value is distributed, and by forcibly flowing such a heat medium, freezing of the entire heat medium circulation path is likely to be suppressed. Further, after taking measures to suppress freezing by the first operation, the hot water heater performs a second operation of burning the burner and driving the pump when the temperature detected by any of the temperature sensors is less than a second threshold value. In this way, since the hot water heater described above can suppress freezing without burning the burner as long as it is below a predetermined standard even when the possibility of freezing is high, it is possible to suppress energy consumption. On the other hand, after taking measures to suppress freezing to some extent by the first operation, when the possibility of freezing is high to the extent that it exceeds a predetermined standard, the hot water heater can circulate the heat medium after heating it, so that freezing can be more reliably suppressed.

[0011] 〔2〕The second threshold value is a value higher than the first threshold value. The hot water heater according to [1].

[0012] In the hot water heater according to [2] above, since the second threshold value that is the condition for the second operation is set higher than the first threshold value, even when performing a freezing suppression operation with suppressed energy consumption, when the possibility of freezing is high, the burner can be burned at an earlier stage, and more reliable freezing suppression measures can be executed.

[0013] 〔3〕In the burner unit, the size of the combustion region of the burner can be switched among a plurality of stages, The control unit performs the second operation so that the range to be burned in the burner unit is the combustion region of the smallest stage among the plurality of stages and the gas supply amount is maximized in the combustion region of the smallest stage. The hot water heating apparatus according to 〔1〕 or 〔2〕.

[0014] The hot water heating apparatus according to 〔3〕 above can suppress the generation of drain by burning the combustion stage with the minimum number of burners with the maximum gas amount, and the temperature of the temperature sensor rises gently, so that the temperature of the heat medium can be measured more accurately.

[0015] 〔4〕The heating circuit includes a tank for storing the heat medium circulating in the heat medium circulation path, The hot water supply circuit, the heating circuit, the temperature sensor, and a housing in which the control unit is housed are provided, As the temperature sensor, an outside air temperature thermistor provided in the housing, a heating high temperature thermistor provided on the downstream side of the heat exchanger in the heat medium circulation path, and a heating low temperature thermistor provided on the downstream side of the heating high temperature thermistor in the heat medium circulation path are provided. The hot water heating apparatus according to any one of 〔1〕 to 〔3〕.

[0016] According to the hot water heating apparatus according to 〔4〕 above, by providing an outside air temperature thermistor in the housing, dirt and aging can be prevented. Here, depending on the usage situation, the temperature inside the housing may become higher than the outside air temperature, and accurate measurement of the outside air temperature may become impossible. Even in such a case, since the first operation can be started based on the temperature detected by either the heating high temperature thermistor or the heating low temperature thermistor that measures the temperature of the heat medium circulation path, freezing of the heat medium can be more reliably suppressed.

[0017] 〔5〕The time during which the second operation is performed is set shorter than the time during which the first operation is performed. The water heating and heating apparatus according to any one of [1] to [4].

[0018] When the heat medium in the second heat dissipation terminal has a certain amount of heat due to the heat in the room, the freeze prevention operation can be completed in a short time.

[0019] (6) A water heating and heating system including the heat dissipation terminal and the water heating and heating apparatus according to any one of [1] to [5].

[0020] <First Embodiment> The following description relates to the water heating and heating apparatus 1 according to the first embodiment. 1. Overall Configuration of the Water Heating and Heating Apparatus 1 FIG. 1 is a schematic circuit diagram of the water heating and heating apparatus 1. The water heating and heating apparatus 1 mainly includes a water heating circuit 2, a heating circuit 3, a bath circuit 4, etc., and is a device capable of performing a water heating operation, an automatic water filling operation, a supplementary heating operation, a heating operation, etc.

[0021] The water heating and heating apparatus 1 is provided with a housing 1A configured as a metal casing inside a housing 1B that serves as an exterior body of the entire apparatus. Inside this housing 1A, a first combustion system unit 5 and a second combustion system unit 6 are configured. The housing 1A is configured as, for example, a metal can body or a metal box body, and is configured to accommodate a water heating burner 8A, a heating burner 33A as an example of a burner, a water heating side heat exchanger 7 as an example of a first heat exchanger, a heating side heat exchanger 32 as an example of a heat exchanger, etc. The first combustion system unit 5 is a combustion system that performs gas combustion and water heating when the water heating circuit 2 performs a water heating operation. The second combustion system unit 6 is a combustion system that performs gas combustion and water heating during a heating operation or a supplementary heating operation.

[0022] The hot water supply circuit 2 is a circuit that heats the water supplied from the outside of the hot water supply and heating machine 1 by the hot water supply side heat exchanger 7 to supply hot water. The hot water supply circuit 2 includes a first combustion system unit 5, specifically, a plurality of hot water supply burners 8A and a hot water supply side heat exchanger 7. Above the hot water supply burner 8A, an ignition plug 85 and a flame sensor 86 are provided. The ignition plug 85 ignites the combustion gas by generating a spark discharge according to an input signal from the control device 70, and the flame generated by the combustion is detected by the flame sensor 86. In the first combustion system unit 5, a hot water supply combustion chamber 5A is provided, and a hot water supply side burner unit 8 and a hot water supply side heat exchanger 7 are provided in the hot water supply combustion chamber 5A. The hot water supply side burner unit 8 includes burner blocks 9A, 9B, and 9C, and each of the burner blocks 9A, 9B, and 9C includes a plurality of hot water supply burners 8A. Each of the plurality of hot water supply burners 8A is configured as a gas burner that burns gas.

[0023] The hot water supply side heat exchanger 7 is a heat exchanger heated by the exhaust gas generated by the hot water supply burner 8A. The hot water supply side heat exchanger 7 includes a hot water supply side first heat exchanger 7A and a hot water supply side second heat exchanger 7B. The hot water supply side first heat exchanger 7A has a plurality of fins 7Z. In the first combustion system unit 5, the hot water supply side first heat exchanger 7A is provided above the plurality of hot water supply burners 8A, and the hot water supply side second heat exchanger 7B is provided above the hot water supply side first heat exchanger 7A. A pipeline 7C is connected between the downstream end of the hot water supply side second heat exchanger 7B and the upstream end of the hot water supply side first heat exchanger 7A, and the hot water flowing through the hot water supply side second heat exchanger 7B flows through the pipeline 7C to the hot water supply side first heat exchanger 7A. The hot water supply side heat exchanger 7 heats the water passing through the inside by the exhaust gas (combustion exhaust gas) generated by burning gas with a plurality of hot water supply burners 8A. The hot water supply side first heat exchanger 7A recovers sensible heat from the combustion exhaust gas discharged from the hot water supply side burner unit 8, and the hot water supply side second heat exchanger 7B recovers latent heat from the combustion exhaust gas discharged from the hot water supply side burner unit 8.

[0024] The hot water supply circuit 2 further includes a water supply pipe 11, a water supply control valve 13A, a water flow sensor 14, a hot water outlet pipe 10, a bypass pipe 12, a bypass control valve 13B, a thermistor 15A (hot water inner cylinder thermistor), a thermistor 15B (hot water outlet thermistor), etc. A water supply pipe 11 is connected to the inlet of the hot water supply side heat exchanger 7. The water supply pipe 11 is connected to an external pipe, and is configured as a pipe that introduces tap water from, for example, a water supply and flows this tap water toward the upstream end (inlet) of the hot water supply side heat exchanger 7. The water flow sensor 14 is a sensor that detects the flow rate of water flowing through the water supply pipe 11. The water supply control valve 13A is a valve for controlling the flow rate of water flowing through the water supply pipe 11, and is a valve that changes the opening degree of the water supply pipe 11 by control. A hot water outlet pipe 10 is connected to the downstream end (outlet) of the hot water supply side heat exchanger 7. The hot water outlet pipe 10 is a pipe that flows the hot water heated by the hot water supply side heat exchanger 7. The hot water outlet pipe 10 forms a path for discharging the hot water heated by the hot water supply side heat exchanger 7 outside the appliance.

[0025] A bypass pipe 12 is connected between the water supply pipe 11 and the hot water outlet pipe 10 so as to bypass the hot water supply side heat exchanger 7. A bypass control valve 13B (bypass control valve) is provided in the bypass pipe 12. The bypass control valve 13B is a valve for controlling the flow rate of water flowing through the bypass pipe 12, and is specifically configured as a valve that changes the opening degree of the bypass pipe 12 by control. A thermistor 15A is provided on the upstream side of the connection portion of the bypass pipe 12 in the hot water outlet pipe 10. The thermistor 15A detects the temperature of the hot water discharged from the hot water supply side heat exchanger 7, and specifically detects the hot water temperature near the outlet of the first hot water supply side heat exchanger 7A. A thermistor 15B is provided on the downstream side of the connection portion of the bypass pipe 12. The thermistor 15B detects the hot water outlet temperature after the water from the bypass pipe 12 is mixed, and specifically detects the temperature of the hot water supplied on the downstream side of the confluence point of the bypass pipe 12 in the hot water outlet pipe 10. The temperatures of the hot water detected by these thermistors 15A and 15B are input to a control device 70 described later.

[0026] The hot water supply circuit 2 further includes a gas pipe 16, a main gas solenoid valve 17, a gas proportional valve 18, and a solenoid valve 19. The gas pipe 16 is a pipe through which gas supplied from outside the hot water supply and heating apparatus 1 via the gas inlet passes, and forms a path for supplying gas to the hot water supply burner 8A. The main gas solenoid valve 17 is provided on the upstream side of the gas pipe 16, and the gas proportional valve 18 is provided on the downstream side of the main gas solenoid valve 17. On the gas pipe 16, the downstream side of the gas proportional valve 18 (hot water supply gas proportional valve) branches, and branch pipes 16A to each of the burner blocks 9A, 9B, 9C and branch pipes 16B to each of the burner blocks 34A, 34B are provided. Each branch pipe 16A is provided with a solenoid valve 19. The solenoid valve 19 (hot water supply switching solenoid valve) switches the branch pipe 16A between an open state (supply possible state) and a closed state (shut-off state), and the supply and shut-off of fuel gas to each of the burner blocks 9A, 9B, 9C are individually switched by the respective solenoid valves 19. By switching the solenoid valve 19, the combustion range of the hot water supply side burner unit 8 is switched, and each combustion range is associated as a stage number.

[0027] The hot water supply circuit 2 further includes a fan 20. The fan 20 has a rotating body 20B that generates wind by its rotation and a drive source 20A that rotates the rotating body 20B. The fan 20 is provided below the hot water supply combustion chamber 5A. By the operation of the fan 20, combustion air is supplied to each of the hot water supply burners 8A and the heating burner 33A, and the combustion exhaust discharged from the hot water supply side burner unit 8 and the heating side burner unit 33 is discharged from the exhaust port 90. Near the fan 20, a current sensor 75 that detects the drive current of the fan 20 and a rotation speed sensor 76 that detects the rotation speed (rotational speed) of the fan 20 are provided. A signal corresponding to the drive current of the fan 20 detected by the current sensor 75 and a signal corresponding to the rotation speed of the fan 20 detected by the rotation speed sensor 76 are output to the control device 70. The hot water supply circuit 2 is also provided with an igniter for ignition, an ignition electrode, a hot water supply flame rod, and the like.

[0028] The bathtub circuit 4 includes a bathtub circulation path 63 and a bathtub heat exchanger 50. The bathtub circulation path 63 forms a flow path configured to circulate the hot water drawn from the external bathtub 52 and introduce it into the bathtub 52. The bathtub heat exchanger 50 is configured as a liquid-liquid heat exchanger that performs heat exchange between the heat medium flowing through the bathtub heating branch path 51 and the hot water flowing through the bathtub circulation path 63.

[0029] The bathtub heat exchanger 50 includes a pipe 50A that forms part of the bathtub circulation path 63, and is provided in a configuration where the bathtub heating branch path 51 is disposed within the pipe 50A. The bathtub circulation path 63 includes the pipe 50A, a bathtub forward pipe 53, and a bathtub return pipe 54. The bathtub circulation path 63 functions as a flow path that draws hot water from the bathtub 52 provided outside the hot water supply and heating unit 1 when the bathtub circulation pump 55 operates, and functions as a flow path that circulates the drawn hot water and introduces it into the bathtub 52. The bathtub return pipe 54 is provided with a bathtub circulation pump 55 that causes the hot water in the bathtub return pipe 54 to flow in a predetermined direction, and a water flow switch 57 that detects that hot water having a predetermined flow rate or more is flowing through the bathtub return pipe 54. The bathtub return pipe 54 is provided between the bathtub 52 outside the appliance and the pipe 50A, and forms a flow path that allows hot water to flow from the bathtub 52 to the pipe 50A when the bathtub circulation pump 55 operates. The bathtub forward pipe 53 is provided between the pipe 50A and the bathtub 52, and forms a flow path that allows hot water to flow from the pipe 50A to the bathtub 52 when the bathtub circulation pump 55 operates. The bathtub forward pipe 53 is provided with a first temperature sensor 64 as a bathtub forward thermistor that detects the temperature of the hot water flowing out from the bathtub heat exchanger 50 to the bathtub 52. The bathtub return pipe 54 is provided with a second temperature sensor 65 as a bathtub return thermistor that detects the temperature of the hot water flowing into the bathtub return pipe 54 from the bathtub 52.

[0030] A drop pipe 59 is connected to the bathtub return pipe 54 in a configuration branched from the hot water outlet pipe 10. The drop pipe 59 communicates with the bathtub return pipe 54. The drop pipe 59 is provided with a hot water supply solenoid valve 60, a drop water amount sensor 61, a plurality of check valves 62, and the like. When the hot water supply solenoid valve 60 provided in the drop pipe 59 is opened during the operation of the hot water supply circuit 2, the hot water heated by the hot water supply circuit 2 is supplied to the bathtub 52 through the drop pipe 59.

[0031] The heating circuit 3 is a circuit that can heat the heat medium by the heating-side heat exchanger 32 and supply the heat medium to the heating terminal (heat radiation terminal) via the heat medium circulation path 48. In the present embodiment, the heat medium is, for example, hot water. Note that, as the heat medium, a fluid other than hot water may be used. The heating circuit 3 includes a second combustion system unit 6 and a heat medium circulation path 48. In the second combustion system unit 6, a heating combustion chamber 6A is provided, and a heating-side burner unit 33 and a heating-side heat exchanger 32 are provided in the heating combustion chamber 6A. The heating combustion chamber 6A is partitioned by a partition member 80 from the hot water supply combustion chamber 5A in the housing 1A, and a temperature sensor 82 for detecting the temperature of the heating combustion chamber 6A is provided on the partition member 80.

[0032] The heating-side burner unit 33 includes burner blocks 34A and 34B, and each of the burner blocks 34A and 34B includes a plurality of heating burners 33A. Each of the plurality of heating burners 33A is configured as a gas burner that burns gas. An ignition plug 85 and a flame sensor 86 are provided above the heating burner 33A.

[0033] The heating-side heat exchanger 32 is a heat exchanger heated by the exhaust gas generated by the heating burner 33A. Specifically, it is a device that acts to heat the heat medium passing through its interior by the combustion exhaust gas of the heating burner 33A. The heating-side heat exchanger 32 includes a heating-side first heat exchanger 32A and a heating-side second heat exchanger 32B. The heating-side first heat exchanger 32A has a plurality of fins 32Z. The second combustion system unit 6 has the heating-side first heat exchanger 32A provided above a plurality of heating burners 33A, and the heating-side second heat exchanger 32B provided above the heating-side first heat exchanger 32A. The heating-side heat exchanger 32 heats the heat medium passing through its interior by the exhaust gas (combustion exhaust gas) generated by burning gas with a plurality of heating burners 33A. The heating-side first heat exchanger 32A is supplied with the exhaust gas (combustion exhaust gas) generated by burning gas with the heating burner 33A (gas burner), and functions to heat the heat medium passing through the heating-side first heat exchanger 32A by the heat of this combustion exhaust gas. The heating-side first heat exchanger 32A recovers sensible heat from the combustion exhaust gas discharged from the heating-side burner unit 33. The heating-side second heat exchanger 32B is supplied with the gas after the combustion exhaust gas has passed through the heating-side first heat exchanger 32A, and functions to heat the heat medium passing through the heating-side second heat exchanger 32B by this gas. The heating-side second heat exchanger 32B recovers latent heat from the combustion exhaust gas discharged from the heating-side burner unit 33.

[0034] The heat medium circulation path 48 is a path for circulating the heat medium so as to pass through the heating-side heat exchanger 32, forming a flow path for the heat medium. The heat medium circulation path 48 includes a common forward flow path 38K as a heating forward pipe, a first internal flow path 38A as a heating high-temperature forward pipe, a second internal flow path 38B as a heating low-temperature forward pipe, and a common flow path 38C as a heating return pipe.

[0035] When the first heat dissipation terminal 39A as a heating terminal is connected as shown in Fig. 1, the heat medium circulation path 48 is configured such that the heat medium circulates through the common flow path 38K, the first internal flow path 38A, the first terminal flow path 38G of the first heat dissipation terminal 39A, and the common flow path 38C. When the second heat dissipation terminal 39Z as a heating terminal is connected as shown in Fig. 1, the heat medium circulation path 48 is configured such that the heat medium circulates through the common flow path 38K, the second internal flow path 38B, the second terminal flow path 38H of the second heat dissipation terminal 39Z, and the common flow path 38C.

[0036] The first internal flow path 38A is connected to the first heat dissipation terminal 39A as a flow path so as to communicate with the first terminal flow path 38G provided outside the hot water heater 1. The first internal flow path 38A is configured as a flow path branching from the branch portion 38J, and is configured as a flow path for flowing the heat medium from the branch portion 38J to the first heat dissipation terminal 39A. A part of the first internal flow path 38A is provided in the first heat exchanger 32A on the heating side, and the heat medium flowing through the first internal flow path 38A is configured to be heated in the first heat exchanger 32A on the heating side.

[0037] The second internal flow path 38B is connected to the second heat dissipation terminal 39Z as a flow path so as to communicate with the second terminal flow path 38H provided outside the hot water heater 1. The second internal flow path 38B is configured as a flow path branching from the branch portion 38J, and is configured as a flow path for flowing the heat medium from the branch portion 38J to the second heat dissipation terminal 39Z.

[0038] The heating circuit 3 further includes an expansion tank 36, a heating circulation pump 37, a heating high-temperature thermistor 40, and a heating low-temperature thermistor 41. The common flow path 38C is a flow path through which the heat medium flowing into the inflow portion 35A returns to the expansion tank 36. In the example of FIG. 1, the upstream end of the common flow path 38C is the inflow portion 35A, and the downstream end of the common flow path 38C is connected to the inlet portion 36C of the expansion tank 36. The common flow path 38C is configured as a pipe that introduces the heat medium exiting from the first heat dissipation terminal 39A and the heat medium exiting from the second heat dissipation terminal 39Z into the interior through the inflow portion 35A and causes it to flow through the heating-side heat exchanger 32 (heating-side second heat exchanger 32B). The common flow path 38C is configured to communicate with the first heat dissipation terminal 39A and the second heat dissipation terminal 39Z, and is connected to the first heat dissipation terminal 39A and the second heat dissipation terminal 39Z as a flow path for flowing the heat medium.

[0039] An intermediate pipe 38D and an intermediate pipe 38E are provided between the outlet of the heating-side second heat exchanger 32B and the inlet of the heating-side first heat exchanger 32A. In the paths of the intermediate pipes 38D and 38E, the expansion tank 36 and the heating circulation pump 37 are provided, and the heat medium can flow from the heating-side second heat exchanger 32B to the heating-side first heat exchanger 32A through the intermediate pipe 38D, the expansion tank 36, and the intermediate pipe 38E. The intermediate pipe 38D is a part of the common flow path 38C and is a flow path between the outlet of the heating-side second heat exchanger 32B and the inlet portion 36C of the expansion tank 36. The intermediate pipe 38E is a pipe formed by a part of the common flow path 38K and the first internal flow path 38A, and is provided between the outlet portion 36B of the expansion tank 36 and the inlet of the heating-side first heat exchanger 32A.

[0040] The common flow path 38K is configured as a flow path that introduces the heat medium flowing out from the outlet portion 36B and flows the heat medium flowing out from the expansion tank 36. A heating circulation pump 37 is provided in the middle of the common flow path 38K. The heating circulation pump 37 causes the heat medium in the common flow path 38K to flow from the expansion tank 36 side to the branch portion 38J side.

[0041] The second internal flow path 38B is provided in a configuration where a plurality of internal branch paths 38F branch off. A low-temperature switching valve 39G is provided in each internal branch path 38F as a valve for opening and closing each branch path 39F. In the example of FIG. 1, one internal branch path 38F communicates with the second heat radiation terminal 39Z and is connected to the second heat radiation terminal 39Z outside the appliance. The downstream sides of the first heat radiation terminal 39A and the second heat radiation terminal 39Z communicate with a common flow path 38C. The first heat radiation terminal 39A is, for example, a high-temperature heating terminal such as a heating blower that blows warm air into a bathroom or a dressing room. The second heat radiation terminal 39Z is, for example, a low-temperature heating terminal such as floor heating in a dressing room.

[0042] The heating high-temperature thermistor 40 is provided in the first internal flow path 38A on the outlet side of the heating-side heat exchanger 32, and detects the temperature of the heat medium flowing out from the heating-side heat exchanger 32 (specifically, the heat medium flowing out from the first heat exchanger 32A on the heating side). The temperature detected by the heating high-temperature thermistor 40 corresponds to the temperature of the heat medium flowing into the first heat radiation terminal 39A during the circulation of the heat medium passing through the first heat radiation terminal 39A. The heating low-temperature thermistor 41 is provided in the expansion tank 36. The temperature detected by the heating low-temperature thermistor 41 corresponds to the temperature of the heat medium flowing into the second heat radiation terminal 39Z during the circulation of the heat medium passing through the second heat radiation terminal 39Z.

[0043] The heating circuit 3 includes a plurality of branch pipes 16B and a plurality of heating switching solenoid valves 44. As described above, the branch pipe 16B is provided in a configuration branched from the gas pipe 16 to the heating circuit 3 side. Each heating switching solenoid valve 44 is provided in each branch pipe 16B. The heating switching solenoid valve 44 is configured to switch the branch pipe 16B in which it is provided between an open state (supply possible state) and a closed state (cut-off state). The supply and cut-off of the fuel gas to each of the burner blocks 34A, 34B are individually switched by each heating switching solenoid valve 44. By switching the heating switching solenoid valve 44, the combustion range of the heating-side burner unit 33 is switched, and each combustion range is associated as a stage number. Note that the heating circuit 3 is also provided with an ignition electrode, a heating frame rod, and the like.

[0044] In the heating circuit 3, hot water heated by the heating-side heat exchanger 32 circulates through the heat medium circulation path 48 due to the operation of the heating circulation pump 37. Specifically, in the heating circuit 3, when the heating circulation pump 37 operates, the hot water flowing through the heat medium circulation path 48 is heated by the combustion exhaust gas discharged from the heating-side burner unit 33 in the heating-side heat exchanger 32, and circulates through the common flow path 38C, the first internal flow path 38A, and the first heat dissipation terminal 39A, and also circulates through the common flow path 38C, the second internal flow path 38B, and the second heat dissipation terminal 39Z. In the example of FIG. 1, hot water is supplied to the first heat dissipation terminal 39A according to the operation of the high-temperature switching valve 39H which is a built-in thermostatic valve. The second heat dissipation terminal 39Z is configured as a low-temperature heating terminal, and hot water is supplied to the second heat dissipation terminal 39Z according to the operation of the low-temperature switching valve 39G which is a thermostatic valve in the appliance.

[0045] As shown in FIG. 1, a branch path 51 for bath heating is provided in a configuration branched from the first internal flow path 38A. The branch path 51 for bath heating branches from a position on the downstream side of the heating-side heat exchanger 32 in the heat medium circulation path 48 (specifically, the downstream side of the first heating-side heat exchanger 32A), and forms a flow path for guiding the heat medium flowing through the heat medium circulation path 48 to the bath heat exchanger 50 side. The branch path 51 for bath heating is connected between the first internal flow path 38A and the common flow path 38C so as to communicate with each other. A control valve 58 is provided on the upstream side of the bath heat exchanger 50 in the branch path 51 for bath heating. The control valve 58 is configured to open and close the branch path 51 for bath heating, and is configured to switch between a closed state in which the water flow passing through itself in the branch path 51 for bath heating is blocked, and an open state in which the water flow passing through itself in the branch path 51 for bath heating is allowed.

[0046] The water heater and space heater 1 further includes a control device 70 which is an example of a control unit, a hot water supply remote controller 71, a bath remote controller 72, a space heater remote controller 73, and a room temperature thermistor (not shown). The control device 70 is an electronic control device including an information processing device such as a CPU, a memory such as a semiconductor memory device, an interface circuit, etc., and functions as a controller for performing various controls. Various programs, data tables, set values, etc. are stored in the memory. The control device 70 is configured to be able to acquire signals from various sensors and switches (thermistors, water volume sensors, switches, etc.), and controls a hot water supply circuit 2, a space heater circuit 3, a bath circuit 4, etc. The room temperature thermistor is provided, for example, in the changing room as a means for detecting the temperature in the changing room. Note that the control device 70 may be constituted by a single device (for example, a controller configured as a single unit), or may be constituted by a plurality of devices.

[0047] 2. Basic operations of the water heater and space heater 1 (Normal hot water supply operation) When a hot water supply faucet provided outside the device to communicate with the hot water outlet pipe 10 is opened and water flows into the appliance, and the water volume sensor 14 outputs a signal indicating the flow of water, the control device 70 rotates the fan 20 for a predetermined time to discharge the combustion exhaust gas stored in the hot water supply combustion chamber 5A (purging). Thereafter, the control device 70 opens the main gas solenoid valve 17 of the gas pipe 16 and each solenoid valve 19, and opens the gas proportional valve 18 at a predetermined opening degree, and controls to supply gas to each hot water supply burner 8A, and operates the igniter to ignite the hot water supply burner 8A. When gas is burned by the hot water supply burner 8A by such control, the water passing through the hot water supply side heat exchanger 7 is heated by the combustion exhaust gas generated by the combustion and the hot water supply operation is performed so that the water flows to the hot water outlet pipe 10, and the heated hot water is discharged from the above hot water supply faucet.

[0048] During the above-mentioned hot water supply operation, the control device 70 monitors the hot water temperature detected by the thermistor 15B provided in the hot water supply pipe 10, and controls the opening and closing of the solenoid valve 19 and adjusts the opening degree of the gas proportional valve 18 so that the hot water temperature becomes the set temperature indicated by the hot water supply remote control 71 or the bath remote control 72. At the same time, the amount of air is continuously changed by controlling the rotational speed of the fan 20. When the hot water supply faucet is closed during the above-mentioned hot water supply operation and the signal output by the water volume sensor 14 indicates a water flow stop state, the control device 70 closes the original gas solenoid valve 17 and the solenoid valve 19 to extinguish the hot water supply burner 8A, and rotates the fan 20 for a predetermined time to perform post-purge.

[0049] (Automatic hot water filling operation) The control device 70 can perform control to automatically fill the bathtub 52 with hot water. For example, when the hot water filling switch provided on the hot water supply remote control 71 or the bath remote control 72 is pressed, the control device 70 sets the hot water temperature to the hot water filling temperature set by the hot water supply remote control 71 or the bath remote control 72 as the target temperature (for example, 40 °C) and starts hot water filling. Specifically, the control device 70 opens the hot water supply solenoid valve 60 in the drop pipe 59 to put the hot water supply circuit 2 into a water flow state, and burns the hot water supply burner 8A so that the heated hot water flows into the hot water supply pipe 10. The hot water flowing through the hot water supply pipe 10 in this way is supplied to the bathtub 52 through the drop pipe 59 and the bath return pipe 54.

[0050] After the control device 70 starts supplying hot water to the bathtub 52 in this way, it monitors whether the water volume detected by the drop water volume sensor 61 provided in the drop pipe 59 (total water volume since the start of automatic hot water filling) has reached the set water volume. When it is confirmed that it has reached, the hot water supply solenoid valve 60 is closed to stop the water flow, the hot water supply burner 8A is extinguished, and the hot water filling is ended. After that, the control device 70 operates the bath circulation pump 55 to circulate the hot water in the bathtub 52 in the bath circuit 4. When the control device 70 finishes hot water filling, it notifies the hot water supply remote control 71 or the bath remote control 72 of the end of hot water filling.

[0051] (Automatic reheating operation) The control device 70 can perform control to automatically reheat (boil up) the water stored in the bathtub 52. For example, when the reheat switch provided on the hot water supply remote control 71 or the bath remote control 72 is pressed, the control device 70 sets the reheat temperature to the target temperature (e.g., 40°C) set on the hot water supply remote control 71 or the bath remote control 72 and starts the reheat. Specifically, the control device 70 ignites the heating burner 33A, opens the control valve 58, operates the bath circulation pump 55, and performs reheat by heating with the bath heat exchanger 50 while circulating the hot water in the bathtub 52. After starting such reheat, the control device 70 monitors whether the hot water temperature detected by the temperature sensor 65 has reached the target temperature. When it is confirmed that the temperature has reached, the control device 70 extinguishes the heating burner 33A, stops the bath circulation pump 55, and ends the reheat. When the control device 70 ends the reheat, it notifies the hot water supply remote control 71 or the bath remote control 72 of the end of the reheat.

[0052] 3. Configuration for supplying a heat medium to the first heat dissipation terminal 39A (high-temperature heating terminal) and the second heat dissipation terminal 39Z (low-temperature heating terminal) The hot water supply and heating machine 1 constitutes a hot water supply system while being connected to the first heat dissipation terminal 39A and the second heat dissipation terminal 39Z, and supplies the heat medium that has been branched and diverted through an internal flow path to the external first heat dissipation terminal 39A and second heat dissipation terminal 39Z.

[0053] As shown in FIG. 1, the downstream end of the common flow path 38K in the heat medium circulation path 48 is a branch portion 38J. The branch portion 38J is a portion that diverts the flow of the heat medium flowing through the common flow path 38K. The upstream side of the branch portion 38J is the common flow path 38K, and the downstream side of the branch portion 38J branches into a first internal flow path 38A and a second internal flow path 38B. The first internal flow path 38A has a reheat branch portion 56 that branches into the bath circuit 4. On the bath circuit 4 side branched at the reheat branch portion 56, the bath heating branch path 51 passes through the bath heat exchanger 50 and is connected to the common flow path 38C. The lower side (downstream side) of the reheat branch portion 56 has a connection portion 46B that branches into the bypass flow path 46.

[0054] The bypass flow path 46 is provided between the common flow path 38C and the first internal flow path 38A. The bypass flow path 46 is a path through which the heat medium can flow so as to bypass between the common flow path 38C and the first internal flow path 38A.

[0055] The downstream end of the first internal flow path 38A is configured to be connectable to the outside and is a first outflow portion 35B through which the heat medium flows out. The first outflow portion 35B is provided at the downstream end of the first internal flow path 38A and is configured as an outlet for flowing out the heat medium from the first internal flow path 38A toward the first terminal flow path 38G. The downstream end of the second internal flow path 38B is configured to be connectable to the outside and is a second outflow portion 35C through which the heat medium flows out. The second outflow portion 35C is provided at the downstream end of the second internal flow path 38B and is configured as an outlet for flowing out the heat medium from the second internal flow path 38B toward the second terminal flow path 38H. The upstream end of the common flow path 38C is configured to be connectable to the outside and is an inflow portion 35A through which the heat medium flows in. The inflow portion 35A is provided on the downstream side of the first terminal flow path 38G and on the downstream side of the second terminal flow path 38H, and is an inlet through which the heat medium flowing through the first terminal flow path 38G flows in, and is also an inlet through which the heat medium flowing through the second terminal flow path 38H flows in.

[0056] Outside the water heater 1, a first heat dissipation terminal 39A and a second heat dissipation terminal 39Z are provided, to which the heat medium is supplied from the water heater 1 and which communicate with the heat medium circulation path 48. The first heat dissipation terminal 39A has a first terminal flow path 38G through which the heat medium flows, and dissipates the heat of the heat medium flowing through the first terminal flow path 38G. In the space near the first heat dissipation terminal 39A, the air is heated by the heat of the heat medium flowing through the first terminal flow path 38G being dissipated. The first heat dissipation terminal 39A is configured as a high-temperature heating terminal. The second heat dissipation terminal 39Z has a second terminal flow path 38H through which the heat medium flows, and dissipates the heat of the heat medium flowing through the second terminal flow path 38H. In the space near the second heat dissipation terminal 39Z, the air is heated by the heat of the heat medium flowing through the second terminal flow path 38H being dissipated. The downstream end of the first terminal flow path 38G and the downstream end of the second terminal flow path 38H are configured to be connectable so as to communicate with the inflow portion 35A of the water heater 1.

[0057] The supply of the heat medium to the first terminal flow path 38G is switched between a state (second state) in which the supply of the heat medium is blocked and a state (first state) in which the supply is permitted by opening and closing the high-temperature switching valve 39H. When the high-temperature switching valve 39H is open, it is allowed for the heat medium to pass through the high-temperature switching valve 39H, and it is allowed for the heat medium to flow from the inside of the first internal flow path 38A, through the first terminal flow path 38G, to the downstream side (inflow portion 35A side) of the high-temperature switching valve 39H. When the high-temperature switching valve 39H is closed, it is blocked for the heat medium to pass through the high-temperature switching valve 39H, and the heat medium does not flow from the inside of the first internal flow path 38A to the downstream side of the high-temperature switching valve 39H. The supply of the heat medium to the second terminal flow path 38H is switched between a state in which the supply of the heat medium is blocked and a state in which the supply is permitted by opening and closing the low-temperature switching valve 39G. When the low-temperature switching valve 39G is open, it is allowed for the heat medium to pass through the low-temperature switching valve 39G, and it is allowed for the heat medium to flow from the inside of the second internal flow path 38B, through the second terminal flow path 38H, to the downstream side (inflow portion 35A side) of the low-temperature switching valve 39G. When the low-temperature switching valve 39G is closed, it is blocked for the heat medium to pass through the low-temperature switching valve 39G, and the heat medium does not flow from the inside of the second internal flow path 38B to the downstream side of the low-temperature switching valve 39G. Both the high-temperature switching valve 39H and the low-temperature switching valve 39G are thermostatic valves. The thermostatic valve, for example, expands the expansion body with the heat of the heating element (Positive Temperature Coefficient) when the power is on, pushes the piston to open the valve so that hot and cold water can flow, and when the power is off, the heating element naturally dissipates heat to contract the expansion body and close the valve.

[0058] The heat medium flowing into the inflow portion 35A circulates through the heat medium circulation path 48 in the water heater 1. Specifically, the heat medium flows downstream from the inflow portion 35A through the common flow path 38C, is heated by the heating-side second heat exchanger 32B, then passes through the expansion tank 36, and further moves downstream by the power of the heating circulation pump 37. Then, the heat medium flowing toward the branch portion 38J is divided at the branch portion 38J into the heat medium flowing toward the first internal flow path 38A and the heat medium flowing toward the second internal flow path 38B. The heat medium flowing through the first internal flow path 38A is heated by the heating-side first heat exchanger 32A on the way.

[0059] The heat medium flowing through the first internal flow path 38A flows out toward the first terminal flow path 38G with the first outflow portion 35B as an outlet. The heat medium flowing through the second internal flow path 38B flows out as a heat medium toward the second terminal flow path 38H with the second outflow portion 35C as an outlet.

[0060] The high-temperature switching valve 39H that opens and closes the first terminal flow path 38G, the low-temperature switching valve 39G that opens and closes the second internal flow path 38B, and the heating circulation pump 37 are controlled by the control device 70. The control device 70 is electrically connected to each of the high-temperature switching valve 39H, the low-temperature switching valve 39G, and the heating circulation pump 37, and performs opening / closing control of the high-temperature switching valve 39H and the low-temperature switching valve 39G and drive control of the heating circulation pump 37.

[0061] 4. Configuration for suppressing freezing The hot water heating machine 1 includes an outside air temperature thermistor 74 that detects the temperature at a location away from the heat medium circulation path 48. The outside air temperature thermistor 74 is provided inside the housing 1B, and is fixed to, for example, the inner wall of the housing 1B to detect the temperature of the outside air (air). The outside air temperature thermistor 74 can be provided at any location as long as it can detect the temperature of the air, and the outside air temperature thermistor 74 may be installed on the outer surface of the housing 1B. The heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 detect the temperature of the heat medium circulation path 48. Control for suppressing freezing of the heat medium is performed based on the detected temperatures TA detected by the outside air temperature thermistor 74, the heating high-temperature thermistor 40, and the heating low-temperature thermistor 41. The outside air temperature thermistor 74, the heating high-temperature thermistor 40, and the heating low-temperature thermistor 41 are examples of a plurality of temperature sensors.

[0062] The heating side burner unit 33 corresponds to an example of a burner unit. In the heating side burner unit 33, the size of the combustion region of the heating burner 33A can be switched in a plurality of stages. In the heating side burner unit 33, both the burner block 34A and the burner block 34B include a plurality of heating burners 33A. The burner block 34B has a larger number of heating burners 33A than the burner block 34A.

[0063] In the heating-side burner unit 33, the areas of the burner block 34A and the burner block 34B are the entire combustible range. Among the entire area of the heating-side burner unit 33, the combustion area of only the area of the burner block 34A is the first stage, the combustion area of only the area of the burner block 34B is the second stage, and the combustion areas of the burner blocks 34A and 34B (simultaneous combustion of the burner blocks 34A and 34B) are the third stage. The combustion area of the first stage has the smallest range of the heating burner 33A to be combusted among the first to third stages. Specifically, the number of heating burners 33A to be combusted among the first to third stages is the smallest. The combustion area of the first stage is also referred to as heating stage 1 or simply stage 1. The combustion area of the second stage has the second smallest range of the heating burner 33A to be combusted among the first to third stages. Specifically, the number of heating burners 33A to be combusted among the first to third stages is the second smallest. The combustion area of the second stage is also referred to as heating stage 2 or simply stage 2. The combustion area of the third stage has the largest range of the heating burner 33A to be combusted among the first to third stages. Specifically, the number of heating burners 33A to be combusted among the first to third stages is the largest. The combustion area of the third stage is also referred to as heating stage 3 or simply stage 3. The control device 70 switches the combustion stage (combustion step) of the heating-side burner unit 33 to three steps according to the required gas supply amount.

[0064] In the heating-only control where the heating operation is controlled without performing the hot water supply operation, the control device 70 controls the combustion of the burner block 34A with the minimum number of heating burners 33A to be burned in stage 1. Next, the combustion of the burner block 34B with a larger number of heating burners 33A than the burner block 34A is controlled in stage 2, and the simultaneous combustion of the burner blocks 34A and 34B is controlled in stage 3. The control device 70 switches the combustion stage (combustion step) of the heating-side burner unit 33 to three stages according to the required gas supply amount. In the heating-only operation (an operation where only heating by the heating circuit 3 is performed while the hot water supply by the hot water supply circuit 2 is stopped), the relationship between the gas supply amount and the number of stages in the heating burner 33A is such that at the minimum settable gas supply amount, it is in heating stage 1. As the gas supply amount is increased from the minimum gas supply amount, when the maximum gas supply amount in heating stage 1 is reached, it switches from heating stage 1 to heating stage 2, and when the maximum gas supply amount in heating stage 2 is reached, it switches from heating stage 2 to heating stage 3.

[0065] When the control device 70 performs the second operation described later, it controls the combustion range of the heating-side burner unit 33 to be the combustion area of the smallest stage (heating stage 1) among the plurality of stages and maximizes the gas supply amount in the combustion area of the smallest stage (heating stage 1). That is, the control device 70 performs the second operation with the combustion of the heating burner 33A in the combustion stage with the minimum number and with the maximum gas supply amount in this number of combustion (the maximum gas supply amount within the range of the gas supply amount that can be supplied to the heating burner 33A when the heating burner 33A is burned with the minimum number in the hot water supply and heating machine 1).

[0066] 5. Processing for suppressing freezing When the power of the hot water supply and heating machine 1 is turned on, the control device 70 performs the processing of FIG. 2. The control device 70 receives the detection signals of the detection temperature TA detected by the outside air temperature thermistor 74, the heating high-temperature thermistor 40, and the heating low-temperature thermistor 41. In step S11, it is determined whether any one of the detection temperatures TA is less than or equal to the first threshold TH1 (TA ≤ TH1). The first threshold TH1 is, for example, 4°C for the outside air temperature thermistor 74, and 3°C for the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41. Note that the temperature of the first threshold TH1 is not limited to this and can be changed as appropriate. For example, the first thresholds of the thermistors 40, 41, and 74 can be set to the same temperature. The first threshold TH1 is lower than the second threshold TH2 described later. By setting the first threshold TH1 low, it is implemented when the need to suppress freezing is high, and when the need to suppress freezing is low, the first operation (and the second operation) is not performed so as not to cause disadvantages to the user. If in step S11, the detection temperature TA of any one of the outside air temperature thermistor 74, the heating high-temperature thermistor 40, and the heating low-temperature thermistor 41 is not less than or equal to the first threshold TH1 (that is, when the detection temperatures TA of all the temperature sensors are greater than the first threshold TH1 set for each temperature sensor (TA > TH1). In the case of No in step S11), the process of step S11 is repeated.

[0067] When the detected temperature TA of any one of the outside air temperature thermistor 74, the heating high temperature thermistor 40, and the heating low temperature thermistor 41 is equal to or lower than the first threshold value TH1 (TA ≤ TH1; Yes in step S11), the process proceeds to step S12. In step S12, the control valve 58 of the hot water heating branch path 51 is opened so that the heat medium flows through the hot water heating branch path 51, and in step S13, the heating circulation pump 37 and the low temperature changeover valve 39G are turned on. Steps S11, S13 to S15 are an example of the first operation. When the heating circulation pump 37 and the low temperature changeover valve 39G are turned on, the measurement of the pump on timer is started in step S14. In step S15, it is determined whether or not the elapsed time measured by the pump on timer has elapsed for 5 minutes, and the process of step S15 is repeated until the elapsed time measured by the pump on timer has elapsed for 5 minutes (No in step S15). When the elapsed time measured by the pump on timer has elapsed for 5 minutes (Yes in step S15), the process proceeds to step S16. The elapsed time (5 minutes) in step S15 is an example of the predetermined time in the first operation. In step S16, it is determined whether or not the preset freeze prevention operation setting is the pump only operation. The freeze prevention operation setting can be selectively set between the pump only operation and the pump and combustion operation. The pump only operation is such that the combustion by the heating burner 33A is not performed and the heating circulation pump 37 is operated. The pump and combustion operation is such that the combustion by the heating burner 33A is performed and the heating circulation pump 37 is operated. The freeze prevention operation setting is stored in the memory of the control device 70 and can be changed by the user by an operation unit such as the remote controllers 71 to 73.

[0068] When the control device 70 determines that it is not set to the pump only operation (No in step S16), since it is set to the pump and combustion operation, after performing the combustion operation control described later in step S17, the process returns to step S16 and the subsequent processing is repeated. On the other hand, when the control device 70 determines that it is set to the pump only operation (Yes in step S16), after performing the pump only operation control described later in step S18, the process returns to step S13 and the subsequent processing is repeated.

[0069] (Combustion operation control) In the combustion operation control, the control device 70 performs the process of FIG. 3. The control device 70 receives the detection signals of the detection temperature TA detected by the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41, respectively, and determines in step S21 whether at least one of the detection temperatures TA is less than the second threshold value TH2 (TA < TH2). The second threshold value TH2 is set to 15°C for both the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41. Note that the temperature of the second threshold value TH2 is not limited to this and can be changed as appropriate. When the detection temperature TA detected by at least one of the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 is less than the second threshold value TH2 (TA < TH2; Yes in step S21), it can be determined that the heat medium in the heat medium circulation path 48 is not warmed by the detection temperature TA. Therefore, the process proceeds to step S22, the measurement of the combustion timer is started, and the combustion of the heating burner 33A is started in step S23. At this time, the combustion stage of the heating burner 33A is set to the minimum stage, and the gas proportional valve 18 and the heating changeover solenoid valve 44 are controlled so that the gas supply amount in this stage is maximized. By setting the combustion stage to the minimum stage, energy consumption can be suppressed. Also, although condensation is a concern when the temperature is low, by maximizing the gas supply amount in one stage, the temperature rises according to the gas supply amount, so the occurrence of condensation can be suppressed.

[0070] Next, in step S24, it is determined whether the combustion continuation criterion has been reached. The combustion continuation criterion is set as follows: for the heating high-temperature thermistor 40, the detection temperature is 60°C; for the combustion timer, the measurement time is 10 minutes; and for the heating burner 33A, detection of ignition failure. When any one of the detection temperature of 60°C of the heating high-temperature thermistor 40, the measurement time of 10 minutes of the combustion timer, and the detection of ignition failure of the heating burner 33A is satisfied, the control device 70 determines that the combustion continuation criterion has been reached.

[0071] When the control device 70 determines that the combustion continuation criterion has not been reached (in the case of No in step S24), the process of step S24 is repeated. When the control device 70 satisfies any one of the detected temperature 60°C of the heating high-temperature thermistor 40, the measured time 10 minutes of the combustion timer, and the detection of ignition failure of the heating burner 33A and determines that the combustion continuation criterion has been reached (in the case of Yes in step S24), it proceeds to step S25 and controls the gas proportional valve 18 and the heating changeover solenoid valve 44 to stop the combustion of the heating burner 33A. When the combustion of the heating burner 33A is stopped, the measurement of the pump-on timer is started in step S26. Next, it is determined in step S27 whether or not the time measured by the pump-on timer has elapsed for 10 minutes, and the process of step S27 is repeated until the elapsed time measured by the pump-on timer elapses for 10 minutes (in the case of No in step S27). When the elapsed time measured by the pump-on timer elapses for 10 minutes (in the case of Yes in step S27), it proceeds to step S35. When the detected temperature TA detected by at least one of the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 in step S35 is less than the second threshold value TH2 (TA < TH2; in the case of Yes in step S35), the combustion operation control (Figure 1) is repeated. When the detected temperature TA detected by both the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 in step S35 is equal to or higher than the second threshold value TH2 (TA ≧ TH2; in the case of No in step S35), it proceeds to step S31 and starts the measurement of the standby timer.

[0072] On the other hand, when it is determined in step S21 that the detected temperatures TA of both the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 are equal to or higher than the second threshold TH2 (TA ≥ TH2; when the answer in step S21 is No), the measurement of the pump-on timer is started in step S28, and the process proceeds to step S29. In step S29, it is determined whether or not 10 minutes have elapsed since the pump-on timer started measuring. Until 10 minutes have elapsed since the pump-on timer started measuring (when the answer in step S29 is No), the process of step S29 is repeated. When 10 minutes have elapsed since the pump-on timer started measuring (when the answer in step S29 is Yes), the process proceeds to step S30. Steps S21 to S29 are an example of the second operation. The control device 70 receives the detection signals of the detected temperatures TA detected by the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41, respectively, and determines in step S30 whether or not the detected temperature TA detected by at least one of the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 is less than the second threshold TH2 (TA < TH2). When the detected temperature TA detected by either the heating high-temperature thermistor 40 or the heating low-temperature thermistor 41 is less than the second threshold TH2 (TA < TH2; when the answer in step S30 is Yes), the process returns to step S22, and the measurement of the combustion timer is started.

[0073] On the other hand, when the detected temperatures TA detected by both the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 are both equal to or higher than the second threshold value TH2 in step S30 (TA ≥ TH2; in the case of No in step S30), the measurement of the standby timer is started in step S31, and the heating circulation pump 37 and the low-temperature switching valve 39G are turned off in step S32. Then, it is determined in step S33 whether or not the elapsed time measured by the pump-on timer has elapsed for a predetermined time, and the process of step S33 is repeated until the predetermined time elapses (in the case of No in step S33). This predetermined time is stored in advance, for example, as a time table in the memory, and an appropriate time is selected according to the operating state. When the time measured by the pump-on timer reaches the predetermined time (in the case of Yes in step S33), the process proceeds to step S34, and it is determined whether or not the detected temperature TA of at least one of the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 is less than the second threshold value TH2 (TA < TH2). When the detected temperatures TA of both the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 are both equal to or higher than the second threshold value TH2 (TA ≥ TH2; in the case of No in step S34), it can be determined that the heat medium in the heat medium circulation path 48 is warmed by the detected temperature TA, so the process returns to step S31 and subsequent processes are performed. When the detected temperature TA of either the heating high-temperature thermistor 40 or the heating low-temperature thermistor 41 is less than the second threshold value TH2 in step S34 (TA < TH2; in the case of Yes in step S34), the process returns to step S22 and the measurement of the combustion timer is started.

[0074] (Pump-alone operation control) In the pump-alone operation control, the control device 70 performs the process of FIG. 4. The control device 70 receives the detection signals of the detection temperature TA detected by the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41, and determines whether the detection temperature TA of at least one of the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 is less than the second threshold value TH2 (TA < TH2) in step S41. The second threshold value TH2 is set to 15°C for both the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41, but the temperature of the second threshold value TH2 can be changed as appropriate. When the detection temperatures TA detected by the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 are both less than the second threshold value TH2 (TA < TH2; Yes in step S41), the process of step S41 is repeated. When the detection temperatures TA detected by both the heating high-temperature thermistor 40 and the heating low-temperature thermistor 41 are equal to or higher than the second threshold value TH2 (TA ≥ TH2; No in step S41) in step S41, it can be determined that the heat medium in the heat medium circulation path 48 is warmed by the detection temperature TA, so the process proceeds to step S42, the measurement of the standby timer is started, and the heating circulation pump 37 and the low-temperature switching valve 39G are turned off in step S43.

[0075] After turning off the heating circulation pump 37 and the low-temperature switching valve 39G, it is determined in step S44 whether the time measured by the standby timer has elapsed for a predetermined time, and the process of step S44 is repeated until the predetermined time has elapsed (No in step S44). This predetermined time is a time table stored in advance in the memory of the control device 70, and an appropriate time is selected according to the operating state. When the time measured by the standby timer reaches the predetermined time (Yes in step S44), the pump-alone operation control is terminated, and the process returns to step S13 in FIG. 1.

[0076] 6. Examples of effects When the detected temperature TA detected by at least one of the plurality of thermistors 40, 41, 74 (temperature sensors) is equal to or lower than a predetermined first threshold value TH1, a first operation is performed to drive the heating circulation pump 37 for a predetermined time. Therefore, due to the driving of the heating circulation pump 37 during the first operation, the heat medium distributed at high and low temperatures in the heat medium circulation path 48 circulates, and freezing of the entire heat medium circulation path can be suppressed. Further, by using the plurality of thermistors 40, 41, 74, it is possible to more accurately determine the possibility of freezing as compared with a configuration that determines freezing with a single thermistor.

[0077] Also, by performing the first operation for a predetermined time, after suppressing freezing to a certain extent, in the second operation, it is determined whether the detected temperature TA detected by at least one of the plurality of thermistors 40, 41, 74 is less than a second threshold value TH2. When it is determined that the detected temperature TA is less than the second threshold value TH2, the heating burner 33A is burned. Thus, when the detected temperature TA is less than the second threshold value TH2 and the possibility of freezing is high, the temperature of the heat medium can be increased by burning the heating burner 33A, and freezing can be more reliably suppressed. Also for the second operation, by using the plurality of thermistors 40, 41, 74, it is possible to more accurately determine the possibility of freezing as compared with a configuration that determines freezing with a single thermistor. Further, during the second operation, when the possibility of freezing is low because the detected temperature TA is equal to or higher than the second threshold value TH2, the consumption of energy required to suppress freezing can be suppressed by not burning the burner. Also, since the time of the second operation (for example, 5 minutes) is set shorter than the time of the first operation (for example, 10 minutes), when the heat medium in the second heat dissipation terminal 39Z has a certain amount of heat due to the heat in the room, the freezing suppression operation can be completed in a short time.

[0078] Also, by burning the minimum number of combustion stages of the heating burner 33A at the maximum gas amount, the generation of drain can be suppressed, and since the temperatures of the thermistors 40, 41, 74 gradually increase, the temperature of the heat medium can be measured more accurately.

[0079] <Other Embodiments> The present invention is not limited to the embodiments described by the above description and drawings. For example, the features of the above-described or below-described embodiments can be combined in any combination within a non-contradictory range. Also, any feature of the above-described or below-described embodiments can be omitted if it is not explicitly specified as essential. Furthermore, the above-described embodiments may be modified as follows.

[0080] In the above embodiment, the operation for suppressing freezing was performed in a state where the low-temperature switching valve 39G was turned on (the first state), but it is not limited to this. The operation for suppressing freezing may be performed in a state where the high-temperature switching valve 39H is turned on (the first state), or the operation for suppressing freezing may be performed in a state where both the low-temperature switching valve 39G and the high-temperature switching valve 39H are turned on (the first state). Also, although control was performed according to whether any one of the plurality of thermistors 74, 40, 41 was less than the threshold value, it is not limited to this, and control may be performed according to whether two or more, or all, of the plurality of thermistors (temperature sensors) are less than the threshold value (or greater than or equal to the threshold value).

[0081] It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed this time, and it is intended that all changes within the scope indicated by the claims or within the scope equivalent to the claims are included.

Explanation of Reference Numerals

[0082] 1: Hot water heater 1A: Container 1B: Housing 2: Hot water supply circuit 3: Heating circuit 4: Bath circuit 5A: Hot water supply combustion chamber 6A: Heating combustion chamber 7: Hot water supply side heat exchanger 7Z: Fin 8: Hot water supply side burner unit 8A: Hot water supply burner 9A: Hot water supply burner block 9B: Hot water burner block 9C: Hot water burner block 10: Hot water outlet pipe 11: Water supply pipe 20: Fan 32: Heating side heat exchanger (heat exchanger) 32A: First heating side heat exchanger 32B: Second heating side heat exchanger 33: Heating side burner unit (burner unit) 33A: Heating burner (burner) 34A: Burner block 34B: Burner block 35A: Inflow part 35B: First outflow part 35C: Second outflow part 36: Expansion tank (tank) 36C: Inlet part 36B: Outlet part 37: Heating circulation pump (pump) 38A: First internal flow path 38B: Second internal flow path 38C: Common return flow path 38K: Common forward flow path 38J: Branch part 39A: First heat dissipation terminal (heat dissipation terminal) 39Z: Second heat dissipation terminal (heat dissipation terminal) 38G: First terminal flow path (terminal flow path) 38H: Second terminal flow path (terminal flow path) 39H: High temperature switching valve (switching valve) 39G: Low temperature switching valve (switching valve) 40: Heating high temperature thermistor (temperature sensor) 41: Heating low temperature thermistor (temperature sensor) 46: Bypass flow path 48: Heat medium circulation path 50: Bath heat exchanger 56: Supplementary heating branch part 70: Control device (control part) 74: Outside air temperature thermistor (temperature sensor)

Claims

1. A hot water heater that supplies a heat medium to a heat dissipation terminal having a terminal flow path through which the heat medium flows and configured to dissipate the heat of the heat medium flowing through the terminal flow path, and controls a switching valve that switches between a first state that permits the supply of the heat medium to the terminal flow path and a second state that shuts off the supply, the hot water heater including a hot water supply circuit that heats water supplied from outside the hot water heater to supply hot water, a burner unit having a burner that burns gas, a heat exchanger heated by the exhaust gas generated by the burner, a heat medium circulation path that is a path for circulating the heat medium together with the terminal flow path and through which the heat medium flows through the heat exchanger, and a pump that causes the heat medium to flow in the heat medium circulation path, heating the heat medium by the heat exchanger and supplying the heat medium to the terminal flow path via the heat medium circulation path, one or more temperature sensors that detect the temperature inside the hot water heater or the outside air, and a control unit that controls the operations of the burner and the pump, wherein the control unit performs a first operation in which when the temperature detected by any of the temperature sensors is equal to or lower than a first threshold value, the switching valve is set to the first state and the pump is driven without burning the burner, and after the first operation, when the temperatures detected by all of the one or more temperature sensors are equal to or higher than a second threshold value, the burner is not burned, and when the temperature detected by any of the temperature sensors is lower than the second threshold value, a second operation is performed in which the burner is burned and the pump is driven. Hot water heater.

2. The second threshold value is higher than the first threshold value. The hot water heater according to claim 1.

3. In the burner unit, the size of the combustion region of the burner is switchable in a plurality of stages, and the control unit performs the second operation such that the combustion range in the burner unit is the smallest combustion region among the plurality of stages and the gas supply amount is maximized in the smallest combustion region. The hot water heater according to claim 1 or claim 2.

4. The heating circuit includes a tank that stores the heat medium circulating in the heat medium circulation path, and includes a housing that houses the hot water supply circuit, the heating circuit, the temperature sensors, and the control unit. As the temperature sensor, an outside air temperature thermistor provided in the housing, a heating high-temperature thermistor provided on the downstream side of the heat exchanger in the heat medium circulation path, and a heating low-temperature thermistor provided on the downstream side of the heating high-temperature thermistor in the heat medium circulation path are provided. The hot water heater according to claim 1 or claim 2.

5. The time during which the second operation is performed is set shorter than the time during which the first operation is performed. The hot water heater according to claim 1 or claim 2.

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