JP2018159487A - Hot water supply system and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water supply system capable of delivering hot water at an intended temperature even when a temperature of water to be input is changed, and a control method for the hot water supply system.SOLUTION: A hot water supply system 100 includes: a primary heat exchanger 11; a heater (gas burner 30, gas proportional valve 33) configured to heat the primary heat exchanger; a CPU 301 configured to control a heating operation of the heater; a secondary heat exchanger 21 located upstream of the primary heat exchanger; and a temperature sensor 190 configured to detect a temperature of water to be introduced to the primary heat exchanger. The CPU 301 is configured to control the heater in accordance with the temperature detected by the temperature sensor 190.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a hot water supply system and a control method thereof, and more particularly, to a hot water supply system including a heat exchange unit including a primary heat exchanger and a secondary heat exchanger and a control method thereof.

  Conventionally, some hot water supply systems include a heat exchanger and a heating unit that heats the heat exchanger. In the hot water supply system, the heating unit heats the heat exchanger. The heat exchanger heats water that has entered from the outside. Thereby, the water introduced into the hot water supply system is heated by the heat exchanger and then discharged.

  In such a hot water supply system, there is one that controls heating by the heating unit in accordance with the temperature of the water that has entered. For example, Japanese Unexamined Patent Application Publication No. 2014-137205 (Patent Document 1) discloses a technique for controlling a heat exchanger according to a detection output of a temperature sensor arranged on the downstream side of the heat exchanger. JP-A-1-247947 (Patent Document 2) discloses a technique for controlling a heating unit in accordance with a temperature detected by a water temperature sensor installed on the downstream side of the heating unit.

JP 2014-137205 A JP-A-1-247947

  However, when a certain amount of water is held inside the hot water supply system, the temperature detected by the water temperature sensor may differ from the temperature of the water that is actually heated in the heat exchanger. For example, this is the case when the incoming water has preheating. When water entering the heat exchanger is introduced via a solar system or the like, temperature unevenness occurs in the piping. When the temperature of water entering the hot water supply system suddenly increases, the temperature detected by the water temperature sensor is high, but the temperature of the water that is held by the hot water system and is heated by the heat exchanger is low. There may be cases. In such a case, if the heating unit is controlled according to the temperature detected by the water temperature sensor, the heat exchanger may not be heated to such an extent that water can be sufficiently heated.

  That is, in the conventional hot water supply system, the temperature change of the water to be heated in the heat exchanger may be delayed with respect to the temperature change of the water that enters the hot water supply system. For this reason, when heating by the heating unit is controlled using the detection result of the temperature of water entering the hot water supply system, when the temperature of the incoming water changes, the temperature of the hot water to be discharged and the set hot water temperature are set. There may be a difference between the temperature.

  Therefore, an object of the present disclosure is to provide a hot water supply system that can discharge hot water at a desired temperature even when the temperature of the incoming water changes, and a control method thereof.

  According to an aspect of the present disclosure, a hot water supply system for heating water is configured to control a primary heat exchanger, a heating device configured to heat the primary heat exchanger, and a heating operation of the heating device. A control device, a secondary heat exchanger located upstream from the primary heat exchanger, and a temperature of water introduced through the secondary heat exchanger and introduced into the primary heat exchanger A control device comprising: a first temperature sensor; and a bypass pipe for mixing water that has passed through the secondary heat exchanger with hot water discharged from the primary heat exchanger without introducing the water into the primary heat exchanger. The heating device is configured to be controlled according to the temperature detected by the first temperature sensor.

  The hot water system may further comprise a flow sensor configured to detect the flow rate of water in the primary heat exchanger. The control device is configured to control the heating device according to the amount of heat calculated according to the detection output of the flow rate sensor, the set value of the supply temperature of the hot water supply system, and the temperature detected by the first temperature sensor. Also good.

  The hot water supply system may further include a distributor for distributing water that has passed through the secondary heat exchanger to the primary heat exchanger and the bypass pipe. The controller may be configured to control the distribution ratio in the distributor according to the temperature detected by the first temperature sensor.

  The hot water supply system may further include a second temperature sensor configured to detect the temperature of hot water discharged from the primary heat exchanger. The control device may be further configured to control the distribution ratio in the distributor according to the temperature detected by the second temperature sensor and the set value of the supply temperature of the hot water supply system.

  According to another aspect of the present disclosure, a primary heat exchanger, a heating device configured to heat the primary heat exchanger, a secondary heat exchanger located upstream of the primary heat exchanger, A first temperature sensor configured to detect the temperature of water passing through the secondary heat exchanger and introduced into the primary heat exchanger, and introducing water passing through the secondary heat exchanger into the primary heat exchanger; A method for controlling a hot water supply system including a bypass pipe for mixing with hot water discharged from a primary heat exchanger without being provided is provided. The control method includes a step of detecting the temperature of water by the first temperature sensor, and a step of controlling the heating device according to the temperature detected by the first temperature sensor.

  According to the present disclosure, in the hot water supply system, the control device includes a heating device that heats the primary heat exchanger that heats water that has passed through the secondary heat exchanger, and a temperature of water before passing through the secondary heat exchanger. Instead, it is controlled according to the temperature of the water that passes through the secondary heat exchanger and is introduced into the primary heat exchanger. Thereby, the hot water supply system can appropriately adjust the temperature of hot water discharged from the primary heat exchanger, and can provide hot water having an appropriate temperature.

It is a schematic block diagram of the hot water supply system according to embodiment of this invention. It is a figure for demonstrating the abbreviation used in this specification. It is a figure which shows typically the structure relevant to the control of the heating by the gas burner 30 of the hot water supply system 100. FIG. 3 is a flowchart of processing for controlling combustion of a gas burner 30 in the hot water supply system 100. 4 is a flowchart of a process for controlling the opening degree of a distribution valve 80.

  Hereinafter, an embodiment of a hot water supply system will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[1. Configuration of hot water supply system]
FIG. 1 is a schematic configuration diagram of a hot water supply system according to an embodiment of the present invention. As shown in FIG. 1, a hot water supply system 100 includes a heating unit 20, a gas burner 30, a combustion can body (hereinafter simply referred to as “can body”) 10 that houses the heating unit 20, a blower fan 40, a water inlet pipe 50, The connecting pipe 51, the bypass pipe 60, the hot water pipe 70, and the controller 300 are included. The heating unit 20 is a part that heats and sends hot water with the amount of heat generated by the combustion of the gas burner 30, and includes a primary heat exchanger 11 that recovers sensible heat and a secondary heat exchanger 21 that recovers latent heat. The outlet of the secondary heat exchanger 21 is connected to the inlet of the primary heat exchanger 11 by a connecting pipe 51.

  Hot water from the water intake pipe 50 is preheated by the secondary heat exchanger 21 and then heated in the primary heat exchanger 11. Hot water heated by the primary heat exchanger 11 and the secondary heat exchanger 21 is discharged from a hot water tap 160 such as a kitchen and a bathroom through a hot water pipe 70.

  The water intake pipe 50 can be supplied with tap water or hot water from an external device. The external device that can be connected to the water inlet pipe 50 includes, for example, a fuel cell power generation unit. The water entered from the water intake pipe 50 is sent to the secondary heat exchanger 21. After passing through the secondary heat exchanger 21, the water is sent to the connecting pipe 51. The connecting pipe 51 and the hot water outlet pipe 70 are connected via the primary heat exchanger 11 and also connected via the bypass pipe 60. That is, the water that has passed through the secondary heat exchanger 21 is sent to the hot water pipe 70 through one of the two paths. The first path is a path that passes through the primary heat exchanger 11, and the second path is a path that passes through the bypass pipe 60 without passing through the primary heat exchanger 11. A distribution valve 80 for controlling the diversion to the bypass pipe 60 is inserted and connected to the connecting pipe 51. Further, a temperature sensor 190 and a flow rate sensor 150 are disposed in the connecting pipe 51.

  The temperature sensor 190 detects the temperature of water in the flow path (connecting pipe 51) between the secondary heat exchanger 21 and the primary heat exchanger 11 (incoming water temperature (primary) Tdpi). That is, the temperature sensor 190 can detect the temperature of the water that is preliminarily heated in the secondary heat exchanger 21 and then enters the primary heat exchanger 11.

  The flow rate sensor 150 detects the flow rate Q of water introduced into the primary heat exchanger 11 out of the flow rate of water entering the hot water supply system 100. Depending on the opening degree of the distribution valve 80, a part of the amount of water supplied to the hot water supply system 100 is diverted from the connecting pipe 51 to the bypass pipe 60. The ratio of the diversion to the total water supply amount is controlled according to the opening degree of the distribution valve 80.

  The outlet pipe 70 is connected to the bypass pipe 60 at the junction 75. Therefore, the hot water from the hot water tap 160 becomes an appropriate temperature by mixing the hot water discharged from the can 10 and the hot water from the bypass pipe 60.

  The hot water outlet 70 is provided with temperature sensors 120 and 130 and a flow rate adjusting valve 90. The temperature sensor 120 is arranged on the upstream side (can body 10 side) of the junction point 75 of the tap water pipe 70 with the bypass pipe 60, and detects the hot water temperature (primary) Tdpo from the can body 10. The temperature sensor 130 is provided on the downstream side (the hot water side) of the junction 75 and detects the hot water temperature after the hot water from the bypass pipe 60 is mixed. The flow rate adjusting valve 90 is provided to control the hot water flow rate.

  The temperature sensor 120 is disposed on the upstream side (the can body 10 side) of the junction point 75 with the bypass pipe 60 of the tapping pipe 70, and the temperature of the tapping water from the can body 10 (hereinafter referred to as tapping temperature (primary) Tdpo). Is detected. The temperature sensor 130 is provided on the downstream side (the hot water side) from the junction 75 and detects the hot water temperature Th after the hot water from the bypass pipe 60 is mixed. The flow rate adjusting valve 90 is provided to control the hot water flow rate.

  The fuel gas delivered from the gas burner 30 is mixed with the combustion air from the blower fan 40. When the air-fuel mixture is ignited by an ignition device (not shown), the fuel gas is burned and a flame is generated. The combustion heat generated by the flame from the gas burner 30 is given to the primary heat exchanger 11 and the secondary heat exchanger 21 in the can 10.

  The primary heat exchanger 11 heats incoming water by heat exchange by sensible heat (combustion heat) of the combustion gas by the gas burner 30. The secondary heat exchanger 21 heats the water passed by the latent heat of the combustion exhaust gas from the gas burner 30 by heat exchange. An exhaust path 15 for exhausting the exhaust gas after heat exchange is provided on the downstream side of the can body 10 in the flow direction of the combustion gas. As described above, in the can 10, the hot water supplied from the inlet pipe 50 is heated by the primary heat exchanger 11 and the secondary heat exchanger 21 by the amount of heat generated by the combustion in the gas burner 30.

  The gas supply pipe 31 to the gas burner 30 is provided with an original gas solenoid valve 32, a gas proportional valve 33 whose opening degree is adjusted in proportion to the amount of current supplied, and capacity switching valves 35a to 35c. The original gas solenoid valve 32 has a function of turning on / off the supply of fuel gas to the gas burner 30. A CPU (Central Processing Unit) 301 described later adjusts the gas flow rate of the gas supply pipe 31 by adjusting the opening of the gas proportional valve 33. In the present embodiment, the gas burner 30 and the gas proportional valve 33 that adjusts the heating power of the gas burner 30 are an example of a heating device configured to heat the primary heat exchanger 11.

  The controller 300 includes a CPU 301, an interface 302 that controls input / output with the outside, a timer 303, and a storage unit 304. The CPU 301 receives an output signal (detection) from each sensor and a user operation via the interface 302, generates a control command to each device in order to control the overall operation of the hot water supply system 100, and passes through the interface 302. Output.

  The CPU 301 samples an output signal (detection) from each sensor via the interface 302, and converts the sampled signal into a measurement value by A / D (Analog / digital) conversion. The user operation includes a command to turn on / off the hot water supply system 100 and a set temperature value (including a set temperature value Tr of hot water supply). The user operation may include an operation on / off command for hot water supply system 100. The control command includes a heating command for controlling the combustion of the gas burner 30. The heating command includes an open command or a close command to the original gas solenoid valve 32 and a command for variably adjusting the opening degree to the gas proportional valve 33.

  In the hot water supply system 100, hot water obtained by mixing the heated water from the can 10 and the non-heated water from the bypass pipe 60 is discharged from the flow rate adjusting valve 90 disposed on the downstream side (the hot water side) from the junction 75. Is done.

  The controller 300 can control the flow rate value Q and the hot water flow rate from the hot water discharge pipe 70 by controlling the opening degree of the flow rate adjusting valve 90. In the hot water supply system 100 shown in FIG. 1, the flow rate value Q is determined by the water supply pressure and the opening degree of the flow rate adjustment valve 90.

  The flow sensor 150 is disposed on the downstream side (can body side) of the distribution valve 80. Therefore, the flow value Q detected by the flow sensor 150 indicates the flow rate (can flow rate) passing through the heating unit 20 stored in the can body 10.

  When the operation command of the hot water supply system 100 is turned on, the controller 300 turns on the combustion operation in the can body 10 when the flow value Q detected by the flow sensor 150 exceeds the MOQ (minimum operating flow value). When the combustion operation is turned on, the original gas solenoid valve 32 is opened, and the supply of fuel gas to the gas burner 30 is started.

  As understood from FIG. 1, the flow rate adjusting valve 90 is inserted and connected to a water passage that passes from the water inlet pipe 50 through the can body 10 to the hot water outlet pipe 70. The flow sensor 150 can detect the flow rate of “water” in the water passage. As shown in FIG. 1, even with the configuration in which the bypass pipe 60 is provided, the hot water flow rate from the flow rate adjustment valve 90 using the distribution ratio η determined by the opening degree of the distribution valve 80 and the value detected by the flow rate sensor 150. Can be identified.

[2. Explanation of terms]
Abbreviations such as temperatures used for hot water supply system 100 are shown in FIG. Each abbreviation will be described with reference to FIG.

  “Incoming water temperature (primary) Tdpi” is a detected temperature of water entering the primary heat exchanger 11 and is detected by the temperature sensor 190. “Tapping water temperature (primary) Tdpo” is a detected temperature of water discharged from the primary heat exchanger 11 and is detected by the temperature sensor 120. “Tempered water temperature (0 m) Tdso” is a detected temperature of water (hot water) discharged from the hot water supply system 100 and is detected by the temperature sensor 130. The “hot-water supply set temperature Tsso” is a set temperature for water (hot water) discharged from the hot-water supply system 100, for example, set by the user and stored in the storage unit 304.

  The “distribution ratio η” represents the ratio of water that is sent to the hot water outlet pipe 70 via the bypass pipe 60 in the water that has entered the incoming pipe 50. The distribution ratio η is calculated according to the equation (1) in FIG. In the formula (1), the hot water supply set temperature Tsso, the tapping temperature (primary) Tdpo, and the incoming water temperature (secondary) Tdsi are used.

  The “can body set temperature Tspo” is a set temperature for water (hot water) discharged from the primary heat exchanger 11 and corresponds to the set temperature with respect to the temperature detected by the temperature sensor 120. As the “can body set temperature Tspo”, the lower one of the value (temperature) calculated according to the equation (2) in FIG. 2 and the value (temperature) calculated according to the equation (3) in FIG. Value is adopted.

  In Formula (2), the hot water supply preset temperature Tsso is used. The value α is a constant that is arbitrarily set, and is set by a user and / or an administrator, for example. The value α may be set before the hot water supply system 100 is shipped. In the formula (3), the hot water supply set temperature Tsso, the incoming water temperature (primary) Tdpi, and the distribution ratio η are used. “Η (max)” in FIG. 2 is a distribution ratio η when the state of the distribution valve 80 is adjusted to a state in which the amount of water fed from the water intake pipe 50 to the bypass pipe 60 is maximized. It is.

  “Required number Nd” is a numerical value (number) indicating the amount of heat required for the gas burner 30 and is calculated according to the equation (4). In the equation (4), the can set temperature Tspo and the incoming water temperature (primary) Tdpi are used. In this specification, the amount of heat (Kcal) generated by the combustion of the gas burner 30 in the hot water supply system 100 is indicated as “number”. The number = 1 corresponds to the amount of heat necessary to increase the hot water temperature at a predetermined temperature (for example, 25 ° C.) under a flow rate of 1 (L / min).

  The “flow rate value Q” is a flow rate of water passing through the primary heat exchanger 11 and is detected by the flow rate sensor 150.

[3. Configuration related to heating control in hot water system]
FIG. 3 is a diagram schematically showing a configuration related to control of heating by the gas burner 30 of the hot water supply system 100. FIG. 3 schematically shows the can 10 and the elements arranged in the water path before and after the can 10. That is, the water introduced from the water inlet pipe 50 is introduced into the secondary heat exchanger 21 and then sent to the connecting pipe 51. Thereafter, the water is distributed to the path including the primary heat exchanger 11 and the bypass pipe 60 by the distribution valve 80. On the connection pipe 51, the flow sensor 150, the temperature sensor 190, and the primary heat exchanger 11 are arrange | positioned in order. The water discharged from the primary heat exchanger 11 is introduced into the outlet pipe 70. On the outlet pipe 70, a temperature sensor 120 and a temperature sensor 130 are sequentially arranged. The water introduced through the bypass pipe 60 is sent downstream of the temperature sensor 120 and upstream of the temperature sensor 130 in the hot water pipe 70.

  In FIG. 3, symbols representing the respective detection outputs are shown in the vicinity of the respective sensors. For example, in the vicinity of the temperature sensor 190, a character “Tdpi” representing “incoming water temperature (primary) Tdpi” detected by the temperature sensor 190 is arranged. In the vicinity of the temperature sensor 120, a letter “Tspo” representing a set value (can body set temperature Tspo) for the temperature detected by the temperature sensor 120 is arranged together with parentheses. In the vicinity of the temperature sensor 130, a letter “Tsso” representing a set value (hot water supply set temperature Tsso) for the temperature detected by the temperature sensor 130 is arranged together with parentheses.

  The controller 300 acquires detection outputs from the temperature sensors 190, 120, and 130 and the flow sensor 150. The controller 300 adjusts the opening degree of the distribution valve 80 and the opening degree of the gas proportional valve 33.

[4. Process flow in hot water system]
(Heating control)
With reference to FIG. 4, the control of the combustion of the gas burner 30 will be described. FIG. 4 is a flowchart of a process for controlling the combustion of the gas burner 30 in the hot water supply system 100. In the hot water supply system 100, for example, the CPU 301 executes a given program, thereby realizing the processing shown in FIG. For example, the CPU 301 executes the above program at predetermined time intervals.

  In step S10, the CPU 301 reads the detected value of the incoming water temperature (primary) Tdpi.

  In step S12, the CPU 301 calculates the required number Nd using the incoming water temperature (primary) Tdpi read in step S10. The request number Nd is calculated, for example, according to Equation (4).

  In step S14, the CPU 301 adjusts the opening of the gas proportional valve 33 in order to realize the thermal power corresponding to the required number Nd calculated in step S12. Thereafter, the CPU 301 ends the process of FIG.

  As described with reference to FIG. 4, in hot water supply system 100, combustion of gas burner 30 is controlled in accordance with incoming water temperature (primary) Tdpi. The incoming water temperature (primary) Tdpi detects the temperature of the water that enters the primary heat exchanger 11. The primary heat exchanger 11 heats water by sensible heat (combustion heat) of combustion gas by the gas burner 30. Therefore, in the hot water supply system 100, the combustion of the gas burner 30 is controlled according to the temperature of the water to be heated by the primary heat exchanger 11, the temperature of the hot water discharged from the primary heat exchanger 11 is appropriately controlled, and the hot water supply system 100 is The temperature of the hot water provided is appropriately controlled.

(Distribution control)
With reference to FIG. 5, control of the opening degree of the distribution valve 80 will be described. FIG. 5 is a flowchart of a process for controlling the opening degree of the distribution valve 80. The processing in FIG. 5 is realized by the CPU 301 executing a given program, for example. CPU301 performs the process of FIG. 5, for example for every predetermined time.

  In step S20, CPU 301 reads out detection outputs of incoming water temperature (primary) Tdpi and tapping temperature (primary) Tdpo.

  In step S22, the CPU 301 calculates the distribution ratio η using the incoming water temperature (primary) Tdpi and the outgoing hot water temperature (primary) Tdpo read in step S20.

  In step S24, the CPU 301 controls the opening degree of the distribution valve 80 according to the distribution ratio η calculated in step S22 to adjust the flow rate of the inlet pipe 50. For example, the opening degree of the distribution valve 80 varies depending on the degree of rotation of the stepping motor. The CPU 301 adjusts the opening degree of the distribution valve 80 by rotating the stepping motor according to the distribution ratio η. Thereafter, the CPU 301 ends the process of FIG.

  In the hot water supply system 100, since a device that changes the temperature of water such as a heating device is not installed between the distributor 80 and the temperature sensor 190, the temperature of the water detected by the temperature sensor 190 depends on the distributor 80. It can be approximated to the temperature of the water before dispensing. Thereby, the temperature detected by the temperature sensor 190 can be used not only as the temperature of water to be heated in the primary heat exchanger 11 but also as the temperature of water before distribution by the distributor 80. Therefore, in hot water supply system 100, the temperature detected by temperature sensor 190 can be used not only in heating control (FIG. 4) but also in distribution control (FIG. 5). Therefore, the number of temperature sensors required to be arranged in hot water supply system 100 can be suppressed as much as possible.

[5. Summary of disclosure]
The present disclosure is summarized as follows, for example.

  (1) The hot water supply system 100 controls the primary heat exchanger 11, the heating device (gas burner 30, gas proportional valve 33) configured to heat the primary heat exchanger, and the heating operation of the heating device. Detects the temperature of water that passes through the secondary heat exchanger and is introduced into the primary heat exchanger, the configured control device (CPU 301), the secondary heat exchanger 21 that is located upstream of the primary heat exchanger The first temperature sensor (temperature sensor 190) configured to perform mixing with the hot water discharged from the primary heat exchanger without introducing water that has passed through the secondary heat exchanger into the primary heat exchanger And the control device is configured to control the heating device in accordance with the temperature (incoming water temperature (primary) Tdpi) detected by the first temperature sensor (FIG. 4).

  (2) The hot water supply system 100 may further include a flow rate sensor 150 configured to detect the flow rate of water in the primary heat exchanger. The control device calculates an amount of heat (in accordance with a detection output (flow rate value Q) of the flow sensor, a set value of the supply temperature of the hot water supply system (hot water set temperature Tsso), and a temperature detected by the first temperature sensor ( You may be comprised so that a heating apparatus may be controlled according to request | requirement number Nd (Formula (4)).

  (3) The hot water supply system 100 may further include a distributor 80 for distributing water that has passed through the secondary heat exchanger to the primary heat exchanger and the bypass pipe. The control device may be configured to control the distribution ratio η (formula (1)) in the distributor according to the temperature (incoming water temperature (primary) Tdpi) detected by the first temperature sensor.

  (4) The hot water supply system 100 may further include a second temperature sensor (temperature sensor 120) configured to detect the temperature of hot water discharged from the primary heat exchanger. The control device further controls the distribution ratio in the distributor according to the temperature detected by the second temperature sensor (temperature of the hot water (primary) Tdpo) and the set value of the supply temperature of the hot water supply system (hot water supply set temperature Tsso). (Equation (1)).

  (5) The method for controlling the hot water supply system 100 includes a step of detecting the temperature of water by the first temperature sensor (step S10), and a step of controlling the heating device according to the temperature detected by the first temperature sensor (step S14). ).

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 10 Can body, 11 Primary heat exchanger, 15 Exhaust path, 20 Heating part, 21 Secondary heat exchanger, 30 Gas burner, 31 Gas supply pipe, 32 original gas solenoid valve, 33 Gas proportional valve, 35a, 35c Capacity switching valve , 40 Blower fan, 50 Water inlet pipe, 60 Bypass pipe, 70 Hot water outlet pipe, 75 Junction point, 80 Distribution valve, 90 Flow rate adjustment valve, 100 Hot water supply system, 120, 130, 190 Temperature sensor, 150 Flow rate sensor, 160 Hot water tap, 300 controller.

Claims (5)

A hot water supply system for heating water,
A primary heat exchanger;
A heating device configured to heat the primary heat exchanger;
A control device configured to control a heating operation of the heating device;
A secondary heat exchanger located upstream of the primary heat exchanger;
A first temperature sensor configured to detect a temperature of water passing through the secondary heat exchanger and introduced into the primary heat exchanger;
A bypass pipe for mixing water that has passed through the secondary heat exchanger with hot water discharged from the primary heat exchanger without introducing water into the primary heat exchanger;
The hot water supply system, wherein the control device is configured to control the heating device in accordance with a temperature detected by the first temperature sensor. A flow sensor configured to detect a flow rate of water in the primary heat exchanger;
The control device controls the heating device according to a heat amount calculated according to a detection output of the flow rate sensor, a set value of a supply temperature of the hot water supply system, and a temperature detected by the first temperature sensor. The hot water supply system of Claim 1 comprised by these. A distributor for distributing water that has passed through the secondary heat exchanger to the primary heat exchanger and the bypass pipe;
The hot water supply system according to claim 1 or 2, wherein the control device is configured to control a distribution ratio in the distributor according to a temperature detected by the first temperature sensor. A second temperature sensor configured to detect the temperature of hot water discharged from the primary heat exchanger;
The control device is further configured to control a distribution ratio in the distributor according to a temperature detected by the second temperature sensor and a set value of a supply temperature of the hot water supply system. 3. The hot water supply system according to 3. A primary heat exchanger, a heating device configured to heat the primary heat exchanger, a secondary heat exchanger located upstream of the primary heat exchanger, and passing through the secondary heat exchanger A first temperature sensor configured to detect a temperature of water introduced into the primary heat exchanger, and the water that has passed through the secondary heat exchanger without introducing the water into the primary heat exchanger. A control method for a hot water supply system comprising a bypass pipe for mixing with hot water discharged from a primary heat exchanger,
Detecting the temperature of the water by the first temperature sensor;
Controlling the heating device according to the temperature detected by the first temperature sensor.

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