JP7184582B2 - Hot water heater and method for controlling hot water heater - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hot water supply apparatus and a control method for the hot water supply apparatus.

Conventionally, the flow rate of water led from the water supply pipe to the heat exchanger and the flow rate of water led from the water supply pipe to the bypass passage were controlled by a bypass valve, and the water heated by the heat exchanger and the water that passed through the bypass valve were separated. There is known a hot water supply apparatus that mixes hot water and discharges hot water at a desired set temperature (see Patent Document 1, for example). In such a hot water supply apparatus, if the bypass valve fails, the hot water to be discharged cannot be adjusted to the desired set temperature, and there is a risk that hot water of high temperature will be discharged.

The hot water supply apparatus disclosed in Patent Document 1 has a flow rate sensor on the heat exchanger side of the branch position of the water supply pipe to the bypass passage, and obtains a hot water supply temperature calculated value from the flow rate of water detected by the flow rate sensor. The hot water supply apparatus determines that the bypass valve is out of order when there is a large difference between the calculated hot water temperature and the hot water temperature detected by the temperature sensor.

Japanese Patent No. 2560578

The hot water supply apparatus disclosed in Patent Document 1 has a flow rate sensor on the heat exchanger side of the branch position of the water supply pipe to the bypass passage. However, in order to detect the total flow rate of water supplied to the water supply pipe, there is a case where a flow rate sensor is provided upstream of the branch position of the water supply pipe to the bypass passage. In this case, since the flow rate of water flowing into the heat exchanger cannot be detected, failure of the bypass valve cannot be determined.

Further, a method of determining failure of the bypass valve when the hot water temperature detected by the temperature sensor rises rapidly is conceivable. However, in some cases, the temperature of the hot water supply may rise gradually depending on the failure of the bypass valve, and in such cases, it cannot be determined that the bypass valve is abnormal. Moreover, the hot water supply temperature may be high (for example, 90° C.) at the time when it is determined that the bypass valve is abnormal, and the bypass valve abnormality cannot be detected early.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hot water supply apparatus and a method of controlling the same that can quickly and reliably determine an abnormality in the flow rate of low-temperature water led to a heat exchanger. With the goal.

According to the present invention, the problem is solved by: a burner; a heat exchanger that heats water circulating therein by heat generated by the burner; an inlet pipe that supplies low-temperature water to the heat exchanger; a bypass pipe that connects the inlet pipe and the outlet pipe and guides the low-temperature water from the inlet pipe to the outlet pipe without passing through the heat exchanger; A feed water temperature detector for detecting the temperature of the low-temperature water supplied to the inlet pipe, an outlet hot water temperature detector for detecting the temperature of the high-temperature water discharged from the outlet pipe, and the high temperature discharged from the outlet pipe. A hot water supply temperature detection unit that detects the temperature of mixed water obtained by mixing water and the low-temperature water that is led from the bypass pipe to the outlet pipe, and adjusts the flow rate of the low-temperature water that is led from the inlet pipe to the bypass pipe. a control unit for controlling the adjustment valve; a temperature of the mixed water detected by the hot water supply temperature detection unit at a predetermined time; Based on the temperature of the high-temperature water detected at a time and the temperature of the low-temperature water detected by the feed water temperature detection unit at a second time that is a second time earlier than the predetermined time, the water is guided to the heat exchanger. a determination unit that determines an abnormality in the flow rate of low-temperature water, wherein the first time is a time required for the high-temperature water that has passed through the hot water supply temperature detection unit to reach the hot water supply temperature detection unit; The problem is solved by the hot water supply apparatus, wherein 2 hours is the time it takes for the low-temperature water that has passed through the feed water temperature detector to reach the hot water supply temperature detector via the bypass pipe.

According to the hot water supply apparatus according to the present invention, an abnormality in the flow rate of the low-temperature water led to the heat exchanger is detected not only by the temperature of the mixed water, but also by the temperature of the low-temperature water supplied to the inlet pipe and the temperature of the low-temperature water discharged from the heat exchanger. Judgment is made considering the temperature of the hot water. Therefore, even if the temperature of the mixed water rises gently, it is possible to reliably determine whether there is an abnormality in the flow rate of the low-temperature water led to the heat exchanger. In addition, the temperature of the low-temperature water supplied to the inlet pipe is a temperature that takes into consideration the time delay until it reaches the hot water supply temperature detector via the bypass pipe, and the temperature of the high-temperature water discharged from the heat exchanger is The temperature is set in consideration of the time delay until the high-temperature water reaches the hot water supply temperature detection unit. Therefore, an abnormality in the flow rate of the low-temperature water led to the heat exchanger can be determined early in consideration of the time delay.

In the hot water supply apparatus according to the present invention, preferably, the determination unit determines an abnormality in the flow rate of the low-temperature water based on a bypass ratio calculation value, and the bypass ratio calculation value is determined by the outlet hot water temperature detection unit. The mixed water detected by the hot water supply temperature detection unit at the predetermined time is a first temperature obtained by subtracting the temperature of the mixed water detected by the hot water supply temperature detection unit at the predetermined time from the temperature of the high-temperature water detected at the time. is a value obtained by dividing the temperature by a second temperature obtained by subtracting the temperature of the low-temperature water detected by the water supply temperature detection unit at the second time.

According to the hot water supply apparatus of this configuration, the value obtained by dividing the first temperature by the second temperature is used to determine the ratio of the flow rate of low-temperature water guided from the inlet pipe to the bypass pipe with respect to the flow rate of low-temperature water supplied from the inlet pipe to the heat exchanger. A bypass ratio calculation value indicating the ratio is obtained. This bypass value calculation value is a different value depending on whether there is an abnormality in the flow rate of the low-temperature water led to the heat exchanger. Therefore, an abnormality in the flow rate of low-temperature water supplied to the heat exchanger can be determined based on the bypass ratio calculated value.

In the hot water supply apparatus according to the present invention, preferably, the determination unit determines that the flow rate of the low-temperature water is abnormal when a value obtained by subtracting the bypass ratio instruction value from the bypass ratio calculation value is equal to or greater than a predetermined threshold value. The bypass ratio indicated value is a value calculated from the degree of opening of the adjustment valve, and the flow rate of the low-temperature water led to the bypass pipe relative to the flow rate of the low-temperature water supplied to the heat exchanger. It is characterized by being a value indicating the ratio of

According to the hot water supply apparatus of this configuration, since the flow rate of the low-temperature water guided to the bypass pipe is adjusted by the opening degree of the adjustment valve, the flow rate of the low-temperature water supplied to the heat exchanger depends on the opening degree of the adjustment valve. A bypass ratio indication is obtained which indicates the proportion of the flow of cold water directed to. This bypass ratio indicated value becomes a value different from the bypass ratio calculated value when there is an abnormality in the flow rate of the low-temperature water led to the heat exchanger. Therefore, an abnormality in the flow rate of the low-temperature water supplied to the heat exchanger can be determined from the value obtained by subtracting the bypass ratio indicated value from the bypass ratio calculated value.

In the hot water supply apparatus according to the present invention, preferably, the control section stops the combustion operation by the burner when the determination section determines that the flow rate of the low-temperature water led to the heat exchanger is abnormal. It is characterized by controlling as follows.
According to the hot water supply apparatus of this configuration, for example, it is possible to suppress a problem in which a low flow rate of low-temperature water boils in the heat exchanger, the internal pressure rises, and the boiling high-temperature water is led to the hot water supply temperature detection unit.

In the hot water supply apparatus according to the present invention, preferably, the regulating valve can adjust the degree of opening by rotating a stepping motor, and the controller controls the low-temperature water guided to the heat exchanger by the determination unit. is determined to be abnormal, the stepping motor is controlled to be in a predetermined initial state.
According to the hot water supply apparatus of this configuration, when it is determined that the flow rate of the low-temperature water led to the heat exchanger is abnormal, the stepping motor enters a predetermined initial state. Abnormal opening can be corrected appropriately.

In the hot water supply apparatus according to the present invention, preferably, the temperature of the mixed water detected by the hot water supply temperature detection unit at the predetermined time, the temperature of the high-temperature water detected by the outlet hot water temperature detection unit at the first time, Abnormality of the regulating valve is determined based on the temperature of the low-temperature water detected by the feed water temperature detection unit at the second time.
According to the hot water supply apparatus of this configuration, it is possible to reliably determine whether the regulating valve is abnormal even when the temperature of the mixed water rises slowly. In addition, an abnormality in the regulating valve can be determined early in consideration of the time delay.

According to the present invention, the above object is a control method for a hot water supply apparatus, wherein the hot water supply apparatus includes a burner, a heat exchanger for heating water flowing through the interior with heat generated by the burner, and the heat exchange apparatus. an inlet pipe for supplying low-temperature water to the vessel, an outlet pipe for discharging high-temperature water from the heat exchanger, and connecting the inlet pipe and the outlet pipe and from the inlet pipe without passing through the heat exchanger A bypass pipe that guides the low-temperature water to the outlet pipe, a feed water temperature detection unit that detects the temperature of the low-temperature water supplied to the inlet pipe, and a hot water outlet that detects the temperature of the high-temperature water discharged from the outlet pipe. a temperature detection unit, a hot water supply temperature detection unit for detecting the temperature of mixed water obtained by mixing the high-temperature water discharged from the outlet pipe and the low-temperature water guided from the bypass pipe to the outlet pipe; an adjustment valve for adjusting the flow rate of the low-temperature water guided to the bypass pipe, the temperature of the mixed water detected by the hot water supply temperature detection unit at a predetermined time, and the temperature of the mixed water detected by the hot water supply temperature detection unit from the predetermined time Based on the temperature of the high-temperature water detected at a first time that precedes the predetermined time by a first time, and the temperature of the low-temperature water that the feed water temperature detection unit detects at a second time that precedes the predetermined time by a second time, a determination step of determining an abnormality in the flow rate of the low-temperature water led to the heat exchanger, wherein the high-temperature water passing through the outlet hot water temperature detection unit reaches the hot water supply temperature detection unit during the first time. and the second time is the time until the low-temperature water that has passed through the water supply temperature detection unit reaches the hot water supply temperature detection unit via the bypass pipe. is solved by the control method of
According to the control method of the hot water supply apparatus of this configuration, it is possible to quickly and reliably determine whether there is an abnormality in the flow rate of the low-temperature water led to the heat exchanger.

Advantageous Effects of Invention According to the present invention, it is possible to provide a hot water supply apparatus and a method of controlling the same that can quickly and reliably determine an abnormality in the flow rate of low-temperature water led to a heat exchanger.

1 is a schematic configuration diagram showing a water heater according to an embodiment of the present invention; FIG. FIG. 2 is a schematic configuration diagram showing a control configuration of the water heater; 4 is a flowchart showing processing executed by a control device; 7 is a graph showing an example of changes over time in temperature and bypass ratio;

Preferred embodiments of the invention are described in detail below with reference to the drawings. Since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are applied. Unless otherwise stated, the invention is not limited to these modes. Further, in each drawing, the same constituent elements are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

An embodiment of a water heater 101 according to the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a water heater 101 according to this embodiment.
Combustion chamber 102 of water heater 101 is provided with first burner 103 , second burner 104 , hot water supply latent heat exchanger 105 , and hot water supply heat exchanger 106 . Hot water supply apparatus 101 is also provided with ignition plug 115 , flame rod 116 , and overheat prevention device (thermal fuse) 117 .

First burner 103 and second burner 104 are provided near hot water heat exchanger 106 and heat hot water heat exchanger 106 . Hot water supply heat exchanger 106 has a large number of fins, and heats water flowing therein by heat generated by at least one of first burner 103 and second burner 104 . The hot water supply latent heat exchanger 105 is provided above the hot water supply heat exchanger 106 and heats the water flowing therein by the latent heat contained in the exhaust gas from the combustion chamber 102 . That is, hot water supply latent heat exchanger 105 is provided at a position in contact with combustion exhaust after hot water supply heat exchanger 106 performs heat exchange by combustion of at least one of first burner 103 and second burner 104. . In this manner, water heater 101 can heat supplied water by combustion of at least one of first burner 103 and second burner 104 .

A combustion fan 108 and a gas pipe 201 are connected to the combustion chamber 102 . The gas pipe 201 is connected to the combustion chamber 102 via a first gas branch pipe 202 and a second gas branch pipe 203 .

Combustion fan 108 sends air necessary for combustion of first burner 103 and second burner 104 to combustion chamber 102 . The gas pipe 201 branches into a first gas branch pipe 202 and a second gas branch pipe 203 . A gas pipe 201 guides gas required for combustion to the first burner 103 via a first gas branch pipe 202 . Also, the gas pipe 201 guides the gas necessary for combustion to the second burner 104 via the second gas branch pipe 203 .

The gas pipe 201 is provided with a source gas solenoid valve 111 and a gas proportional valve 112 . A first gas solenoid valve 113 is provided in the first gas branch pipe 202 . A second gas electromagnetic valve 114 is provided in the second gas branch pipe 203 . The source gas electromagnetic valve 111 controls the supply and stop of gas to the first burner 103 and the second burner 104 . The gas proportional valve 112 controls the amount of fuel supplied to the corresponding first burner 103 and second burner 104 by the valve opening. The first gas solenoid valve 113 and the second gas solenoid valve 114 control fuel supply/stop to the corresponding first burner 103 and second burner 104 .

Combustion chamber 102 of hot water supply device 101 is further provided with hot water supply tray 125 as a receiving portion for drain (water). When water vapor present in combustion exhaust in combustion chamber 102 condenses on the surface of hot water supply latent heat exchanger 105 at a relatively low temperature and drips, the dripping drain is collected in hot water supply tray 125 . Hot water supply tray 125 is connected to a neutralizer (not shown) through a drain discharge pipe (not shown).

Inlet pipe 204 of hot water supply latent heat exchanger 105 is a pipe that supplies water (low-temperature water) to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 . The inlet pipe 204 is provided with a water supply thermistor (water supply temperature detector) 120 , a water quantity sensor 121 , and a bypass servo (regulating valve) 122 . Water supply thermistor 120 detects the temperature of water (low temperature water) supplied to inlet pipe 204 . Water quantity sensor 121 detects the flow rate of water (low-temperature water) flowing through inlet pipe 204 of hot water supply latent heat exchanger 105 .

Bypass servo 122 is provided at the connection between inlet pipe 204 of hot water supply latent heat exchanger 105 and bypass pipe 211 and controls the amount of water (low-temperature water) guided from inlet pipe 204 to bypass pipe 211 . Bypass pipe 211 is a pipe that connects inlet pipe 204 of hot water supply latent heat exchanger 105 and outlet pipe 207 of hot water supply heat exchanger 106 . Bypass pipe 211 guides water (low-temperature water) from inlet pipe 204 to outlet pipe 207 without passing through hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 .

Inlet pipe 204 of hot water supply latent heat exchanger 105 is connected to outlet pipe 205 of hot water supply latent heat exchanger 105 . A drain plug 127 is provided at the end of the outlet pipe 205 of the hot water supply latent heat exchanger 105 . An inlet pipe 206 of hot water supply heat exchanger 106 branched from outlet pipe 205 of hot water supply latent heat heat exchanger 105 is connected to outlet pipe 205 of hot water supply latent heat exchanger 105 . Inlet pipe 206 of hot water supply heat exchanger 106 is provided with water pipe thermistor 118 . Water pipe thermistor 118 detects the temperature of water flowing through inlet pipe 206 of hot water heat exchanger 106 .

Inlet pipe 206 of hot water heat exchanger 106 is connected to outlet pipe 207 of hot water heat exchanger 106 . Outlet pipe 207 is a pipe for discharging heated water (high-temperature water) from hot water supply heat exchanger 106 . Outlet pipe 207 of hot water supply heat exchanger 106 is provided with a heat exchange thermistor (hot water supply temperature detection unit) 119 , a hot water supply thermistor (hot water supply temperature detection unit) 123 , and a hot water amount servo 124 .

Heat exchange thermistor 119 detects the temperature of water (high-temperature water) that is discharged from outlet pipe 207 of hot water heat exchanger 106 and immediately after passing through hot water heat exchanger 106 . Hot water supply thermistor 123 measures the temperature of water (mixed water) obtained by mixing water (high temperature water) discharged from outlet pipe 207 of hot water supply heat exchanger 106 and water (low temperature water) guided from bypass pipe 211 to outlet pipe 207. to detect The hot water amount servo controls the amount of hot water guided to the hot water supply pipe 212 and the hot water supply pipe 213 .

Water heater 101 includes a control device 130 that controls each part of water heater 101 . FIG. 2 is a schematic configuration diagram showing a control configuration of water heater 101. As shown in FIG. As shown in FIG. 2 , the control device 130 includes a control section 131 configured by an arithmetic processing device such as a CPU, a determination section 132 and a storage section 133 . The determination unit 132 is implemented as, for example, a program executed by the control device 130 .

Control unit 131 controls each unit of water heater 101 . The controller 131 controls the bypass servo 122 so that the flow rate of water (low-temperature water) guided from the inlet pipe 204 to the bypass pipe 211 reaches a predetermined target flow rate. The bypass servo 122 is a valve that adjusts the degree of opening by rotating a stepping motor (not shown) forward or backward. The control unit 131 adjusts the opening degree of the bypass servo 122 by transmitting a pulse signal for rotating the stepping motor to the bypass servo 122 .

Determination unit 132 determines an abnormality in the flow rate of water guided from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 . Abnormality in the flow rate of water guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 is, for example, the failure of bypass servo 122, etc., to cause water to be guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106. This is an abnormality in which the flow rate is extremely low. When the flow rate of water guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 becomes extremely low, the water heated by hot water supply heat exchanger 106 evaporates, the internal pressure of hot water supply heat exchanger 106 rises, and boiling occurs. The hot water is led to the hot water supply thermistor. In this case, there is a possibility that water (low-temperature water) does not flow from bypass pipe 211 to outlet pipe 207 due to the increased internal pressure, and boiling high-temperature water is led to hot water supply pipes 212 and 213 .

Water heater 101 of the present embodiment can measure the total amount of water supplied to inlet pipe 204 by water quantity sensor 121, but the flow rate of water introduced to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 cannot be measured. can't. Therefore, the hot water supply apparatus 101 of the present embodiment calculates the bypass ratio calculation value Bpcalc and the bypass ratio instruction value Bpnow, and determines whether there is an abnormality in the flow rate of the water introduced to the hot water supply latent heat exchanger 105 and the hot water supply heat exchanger 106. .

Determining unit 132 calculates bypass ratio calculation value Bpcalc and bypass ratio instruction value Bpnow, and based on these, determines an abnormality in the flow rate of water guided from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106. judge. Here, the bypass ratio is the flow rate of water (low temperature water) supplied from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 (low temperature water) introduced from inlet pipe 204 to bypass pipe 211. refers to the flow rate ratio of

The bypass ratio instruction value Bpnow is a value calculated from the degree of opening of the bypass servo 122 . When the opening degree of the bypass servo 122 is 0 (fully closed), no water (low temperature water) is led to the bypass pipe 211 . Therefore, the bypass ratio instruction value Bpnow becomes zero. When the degree of opening of bypass servo 122 is fully open, water (low-temperature water) at a predetermined flow rate in water heater 101 is guided to bypass pipe 211 . In this case, the bypass ratio instruction value Bpnow is a predetermined value of about 3 to 4, for example. The determination unit 132 reads a table showing the relationship between the opening degree of the bypass servo 122 and the bypass ratio from the storage unit 133 and compares it with the current opening degree of the bypass servo 122 to calculate the bypass ratio instruction value Bpnow. .

The bypass ratio calculated value Bpcalc is a bypass ratio calculated based on the water temperature. Determination unit 132 detects the temperature of water (low temperature water) flowing through inlet pipe 204 detected by water supply thermistor 120, and the temperature of water (high temperature water) heated by hot water supply heat exchanger 106 detected by heat exchange thermistor 119. , and the temperature of the water (mixed water) detected by the hot water supply thermistor 123, the bypass ratio calculation value Bpcalc is calculated.

Specifically, determination unit 132 calculates bypass ratio calculation value Bpcalc using the following equation (1).
Bpcalc=(Thex(Δ1)−Tout)/(Tout−Tin(Δ2)) (1)
Here, Tout is the temperature of water (mixed water) detected by hot water supply thermistor 123 at predetermined time Tnow. Thex(Δ1) is the temperature of the water (high-temperature water) detected by the heat exchange thermistor 119 at the time (first time) that is the first time Δ1 before the predetermined time Tnow. Tin(Δ2) is the temperature of water (low-temperature water) detected by the water supply thermistor 120 at a time (second time) that is a second time Δ2 before the predetermined time Tnow.

The first time Δ1 is the time until water (high-temperature water) that has passed through heat exchange thermistor 119 reaches hot water supply thermistor 123 . Second time Δ2 is the time until water (low-temperature water) that has passed through water supply thermistor 120 reaches hot water supply thermistor 123 via bypass pipe 211 . The first time Δ1 and the second time Δ2 are calculated by the determination unit 132 using the following equations (2) and (3), respectively.
Δ1=U1/(W/(1+Bpnow)) (2)
Δ2=Z1/(W·Bpnow/(1+Bpnow)) (3)

Here, U1 is the volume of water (high-temperature water) held by outlet pipe 207 in the region from heat exchange thermistor 119 to hot water supply thermistor 123 . Z1 is the volume of water (low-temperature water) held by inlet pipe 204, bypass pipe 211, and outlet pipe 207 in a region from water supply thermistor 120 to hot water supply thermistor 123; It is assumed that the values of U1 and Z1 are measured in advance and stored in the storage unit 133 . W is the flow rate [L/sec] of water (low temperature water) supplied to the inlet pipe 204 . W is detected by the water quantity sensor 121 .

Based on U1 and Z1 stored in the storage unit 133, W obtained from the water quantity sensor 121, and the bypass ratio instruction value Bpnow calculated in advance, the determination unit 132 calculates the third 1 hour Δ1 and 2nd hour Δ2 are calculated. From the first time Δ1, determination unit 132 obtains temperature Thex(Δ1) of water (high-temperature water) detected by heat exchange thermistor 119 at a time (first time) that is the first time Δ1 before predetermined time Tnow. Similarly, determination unit 132 determines temperature Tin(Δ2) of water (low-temperature water) detected by water supply thermistor 120 at a time (second time) that is a second time Δ2 before predetermined time Tnow from second time Δ2. obtain.

The temperature detected by the heat exchange thermistor 119 is stored in the storage unit 133 for a predetermined period (for example, 20 seconds) from the current time along with time information indicating the time when the temperature was detected. Similarly, the temperature detected by the water supply thermistor 120 is stored in the storage unit 133 for a predetermined period of time from the current time along with the time information indicating the time when the temperature was detected. The determining unit 132 selects the water (high-temperature water) temperature Thex( Δ1) is obtained. Further, the determining unit 132 selects the temperature of the water (low-temperature water) detected at the time (second time) that is the second time Δ2 before the predetermined time Tnow from among the temperatures at a plurality of times stored in the storage unit 133. Obtain Tin(Δ2). Then, determination unit 132 calculates bypass ratio calculation value Bpcalc from equation (1).

Next, processing executed by the control device 130 will be described with reference to the flowchart of FIG.
In step S301, the determination unit 132 reads from the storage unit 133 a table showing the relationship between the opening degree of the bypass servo 122 and the bypass ratio, and compares it with the current opening degree of the bypass servo 122 to obtain the bypass ratio instruction value. Calculate Bpnow.
At step S302, the determination unit 132 calculates the bypass ratio calculation value Bpcalc using the equation (1).

In step S303, determination unit 132 determines whether a value obtained by subtracting bypass ratio instruction value Bpnow from bypass ratio calculation value Bpcalc is equal to or greater than bypass ratio threshold value Bpth. The determination unit 132 advances the process to step S304 if YES, and executes step S301 again if NO. If the bypass ratio calculation value Bpcalc is 3.8 even though the bypass ratio instruction value Bpnow is 0 (zero) when the bypass ratio of the bypass servo 122 is 3.8, the step-out control system component However, if the bypass ratio calculation value Bpcalc is 4 (the value obtained by subtracting the bypass ratio instruction value Bpnow from the bypass ratio calculation value Bpcalc is 4), the state is clearly abnormal. Therefore, as the bypass ratio threshold value Bpth, an arbitrary value of 3 to 5, for example, can be set.

Here, 4, which is the median value of the bypass ratio threshold value Bpth, is the bypass ratio value ( maximum bypass ratio). When the value obtained by subtracting the bypass ratio indicated value Bpnow from the bypass ratio calculated value Bpcalc exceeds 4, which is the maximum value of the bypass ratio, a phenomenon occurs in which the water heated in the hot water heat exchanger 106 boils due to factors other than damage. is clearly occurring. Therefore, in order to determine that the flow rate of water led from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 is abnormal, a phenomenon in which water heated in hot water supply heat exchanger 106 boils is introduced. A bypass ratio threshold Bpth is set to indicate that such a phenomenon has occurred or is highly likely to occur.

For example, using integral control of proportional-integral-derivative control (PID control) (in particular, using integral action that emphasizes past data, even if the bypass ratio threshold Bpth is 3 or less), the bypass ratio When the threshold Bpth exceeds 4 (occurrence of boiling) is predicted, it may be determined that the bypass ratio threshold Bpth is greater than or equal to the bypass ratio threshold Bpth.

Further, in the above description, a value within a range centering on the maximum value of the bypass ratio is used as the bypass ratio threshold value Bpth, but other modes may be used. For example, if the boiling phenomenon occurs due to an abnormality in the flow rate of water led from the inlet pipe 204 to the hot water supply latent heat exchanger 105 and the hot water supply heat exchanger 106, there is a high possibility that the boiling phenomenon will occur, or if the boiling phenomenon occurs Other thresholds indicative of a boiling phenomenon, such as what is predicted, may be employed as the bypass ratio threshold Bpth.
Further, in step S303, the determination unit 132 may determine whether or not the value obtained by dividing the bypass ratio calculation value Bpcalc by the bypass ratio instruction value Bpnow is equal to or greater than the bypass ratio threshold value Bpth.

In the above description, the maximum value of the bypass ratio (the maximum value of the hot water mixing ratio) is 4, but the maximum value of the bypass ratio (the maximum value of the hot water mixing ratio of the hot water supply device) is another value. , a bypass ratio threshold value Bpth suitable for the maximum value of the bypass ratio (the maximum value of the hot water mixing ratio) of the water heater is set. For example, if the maximum value of the bypass ratio (maximum value of the hot water mixture ratio) is 10, an arbitrary value from a range centering on 10 (eg, 8 to 12) is adopted as the bypass ratio threshold value Bpth.

If the value obtained by subtracting the bypass ratio instruction value Bpnow from the bypass ratio calculation value Bpcalc is equal to or greater than the bypass ratio threshold value Bpth, determination unit 132 conducts the heat from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106. It is determined that the flow rate of the water that is drained is abnormal. If there is no abnormality in the flow rate of water guided from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106, bypass ratio calculated value Bpcalc and bypass ratio indicated value Bpnow are approximately the same.

When the bypass servo 122 fails in the fully open state, the bypass ratio instruction value Bpnow becomes 0 when the controller 131 controls the bypass servo 122 to fully close. In this case, since bypass servo 122 is fully open, the flow rate of water introduced from inlet pipe 204 to hot water latent heat exchanger 105 and hot water heat exchanger 106 decreases, and bypass ratio calculated value Bpcalc increases.

Here, although the abnormality in the flow rate of water led from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 is assumed to be due to failure of bypass servo 122, other factors are also conceivable. For example, the fact that the inlet pipe 204, the outlet pipe 207, and the bypass pipe 211 are partly frozen and the water cannot flow is also a cause of abnormality.

In step S304, control unit 131 stops the combustion operation of first burner 103 because there is an abnormality in the flow rate of water led from inlet pipe 204 to hot water latent heat exchanger 105 and hot water heat exchanger .
In step S305, control unit 131 stops the combustion operation of second burner 104 because the flow rate of water led from inlet pipe 204 to hot water latent heat exchanger 105 and hot water heat exchanger 106 is abnormal.

In step S306, the control unit 131 controls the stepping motor that drives the bypass servo 122 to be in a predetermined initial state. The predetermined initial state means a state in which the stepping motor has reliably recognized the origin position. If the abnormality in the flow rate of the water led to the hot water supply latent heat heat exchanger 105 and the hot water supply heat exchanger 106 is caused by stepping out of step or disconnection of the stepping motor, the stepping motor can be brought into a predetermined initial state. You can fix the problem.

Here, an example of temporal changes in temperature and bypass ratio will be described with reference to FIG. FIG. 4 shows an example of heating water guided from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 without performing the process shown in FIG. 3 of the present embodiment. The example shown in FIG. 4 is an example in which the bypass servo 122 is out of order in the fully open state.

When hot water supply device 101 starts operating and combustion is performed by first burner 103 and second burner 104, the temperature detected by heat exchange thermistor 119 and the temperature detected by hot water supply thermistor 123 rise. The bypass ratio instruction value Bpnow is 0 until time t2. This indicates that the controller 131 controls the opening of the bypass servo 122 to be 0 (fully closed).

However, since the bypass servo 122 is actually out of order in the fully open state, the bypass ratio calculated value Bpcalc rises sharply from time t1. This is because the bypass servo 122 is fully open, and the flow rate of water guided from the inlet pipe 204 to the hot water supply latent heat exchanger 105 and the hot water supply heat exchanger 106 is low.

In the example shown in FIG. 4, the combustion operation by the first burner 103 and the second burner 104 is not stopped even if the value obtained by subtracting the bypass ratio instruction value Bpnow from the bypass ratio calculation value Bpcalc becomes equal to or greater than the bypass ratio threshold value Bpth. Therefore, the temperature detected by heat exchange thermistor 119 and the temperature detected by hot water supply thermistor 123 immediately after time t2 are the maximum values. The temperature of the heat exchange thermistor 119 rises to the temperature at which water boils inside.

In the present embodiment, if the value obtained by subtracting the bypass ratio instruction value Bpnow from the bypass ratio calculation value Bpcalc is equal to or greater than the bypass ratio threshold value Bpth, the determination unit 132 controls the hot water supply latent heat exchanger 105 and the hot water supply heat from the inlet pipe 204. It is determined that the flow rate of water led to the exchanger 106 is abnormal. Therefore, it is possible to determine that there is an abnormality between time t1 and time t2 in FIG. Therefore, the temperature detected by heat exchange thermistor 119 and the temperature detected by hot water supply thermistor 123 do not become maximum immediately after time t2.

The operation and effects of the hot water supply apparatus 101 of the present embodiment described above will be described.
According to hot water supply apparatus 101 of the present embodiment, the temperature of water (mixed water) detected by hot water supply thermistor 123 when an abnormality in the flow rate of water (low-temperature water) guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 is detected. In addition, the temperature of the water (low temperature water) supplied to the inlet pipe 204 and the temperature of the water (high temperature water) discharged from the hot water supply heat exchanger 106 are taken into consideration for determination. Therefore, even if the temperature of water (mixed water) detected by hot water supply thermistor 123 rises slowly, the flow rate of water (low-temperature water) guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 is abnormal. can be reliably determined.

The temperature of water (low-temperature water) supplied to inlet pipe 204 is a temperature that takes into consideration the time delay until it reaches hot water supply thermistor 123 via bypass pipe 211. The temperature of water (high-temperature water) discharged from heat exchanger 106 is a temperature that takes into consideration the time delay until water reaches hot water supply thermistor 123 . Therefore, an abnormality in the flow rate of the water (low-temperature water) guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 can be determined early in consideration of the time delay.

According to the hot water supply apparatus 101 of the present embodiment, the flow rate of water (low-temperature water) supplied from the inlet pipe 204 to the hot water latent heat exchanger 105 and the hot water heat exchanger 106 is bypassed from the inlet pipe 204 according to the equation (1). A bypass ratio calculation value Bpcalc indicating the ratio of the flow rate of water (low-temperature water) guided to the pipe 211 is obtained. This bypass value calculation value Bpcalc has a different value depending on whether there is an abnormality in the flow rate of water (low-temperature water) guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 . Therefore, an abnormality in the flow rate of water (low-temperature water) supplied to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 can be determined based on bypass ratio calculated value Bpcalc.

According to the hot water supply apparatus 101 of the present embodiment, the flow rate of water (low-temperature water) guided to the bypass pipe 211 is adjusted according to the degree of opening of the bypass servo 122. and a bypass ratio indication value Bpnow indicating the ratio of the flow rate of water (low temperature water) led to bypass pipe 211 to the flow rate of water (low temperature water) supplied to hot water supply heat exchanger 106 . If there is an abnormality in the flow rate of water (low-temperature water) guided to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106, bypass ratio instruction value Bpnow becomes a value different from bypass ratio calculation value Bpcacl. Therefore, an abnormality in the flow rate of water (low-temperature water) supplied to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 can be determined from a value obtained by subtracting bypass ratio indicated value Bpnow from bypass ratio calculated value Bpcalc. .

According to hot water supply apparatus 101 of the present embodiment, control unit 131 determines that the flow rate of water (low-temperature water) led to hot water supply latent heat heat exchanger 105 and hot water supply heat exchanger 106 is abnormal. First, the combustion operation by the first burner 103 and the second burner 104 is controlled to stop. Therefore, for example, it is possible to suppress a problem in which a small flow rate of water boils inside hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 , the internal pressure rises, and the boiling water is led to hot water supply thermistor 123 .

According to hot water supply apparatus 101 of the present embodiment, when it is determined that the flow rate of water (low-temperature water) guided to hot water supply latent heat heat exchanger 105 and hot water supply heat exchanger 106 is abnormal, the stepping motor is set to a predetermined initial temperature. state. Therefore, it is possible to appropriately correct the abnormal opening of the bypass servo 122 due to step-out or disconnection.

Here, the difference between this embodiment and Patent Document 1 will be described.
Patent Document 1 describes "a hot water supply passage having a heat exchanger, a bypass passage connected to the hot water supply passage so as to bypass the inlet side and the outlet side of the heat exchanger, a bypass valve provided in the bypass passage, and a bypass valve. A valve control device that controls the degree of opening, a flow rate detector that detects the flow rate passing through the heat exchanger, an inlet water temperature detector that detects the temperature of incoming water, and a hot water temperature detector that detects the temperature of hot water discharged from the heat exchanger. , a mixing temperature detector that detects the mixed temperature of the hot water discharged from the heat exchanger and the water that has passed through the bypass passage, and each detection value and valve control of the flow rate detector, the incoming water temperature detector, and the hot water temperature detector. a failure detection unit that detects a failure of the bypass valve by calculating the hot water supply temperature from the control amount of the bypass valve by the device and comparing the calculated value of the hot water supply temperature with the hot water supply temperature detected by the mixing temperature detector. A mixing-type water heater” is disclosed.

The calculation output of the pseudo set temperature calculation unit 18 and the detection signals of the incoming water temperature sensor 6 and the flow rate sensor 7 are output to the FF control unit 16, and the FF control unit 16 outputs the sensor output of the flow rate detector and the incoming water temperature detector. Based on this, the combustion power of the gas burner 13 is feedforward controlled by the capacity control device 14 so that the temperature of the discharged hot water from the heat exchanger 2 becomes the pseudo set temperature Tps (eg, 80° C.).

In Patent Document 1, when a failure occurs in the bypass valve 8, for example Qcc/Qh=α(N)=1 (Tps=80° C. Tc=20° C.), Qc/Qh=α(N)= In the case of 0.2, hot water is discharged (for example, hot water is discharged at 70° C.), and in the case of Qc/Qh=α(N)=5, hot water is not discharged (eg, hot water is discharged at 30° C.).

For example, when Qc/Qh = α(N) = 0.2, if there is no hot water temperature detected by the mixing temperature detector (if the mixing temperature detector does not detect an unexpected hot water temperature), the failure detection unit Since the failure of the bypass valve cannot be detected and determined, even if a failure occurs in the bypass valve, the ability of the heat exchanger 2 is immediately reduced (even if the temperature of the hot water discharged from the heat exchanger 2 is lowered), for example Even if hot water supply is stopped (combustion is stopped), the piping between the outlet of the heat exchanger 2 and the mixing temperature sensor is already filled with high temperature hot water. There is a problem that it is not possible to prevent high-temperature hot water from being discharged until the hot water from the piping ends.

In the first place, unless an unexpected hot water supply temperature is detected by the mixing temperature detector, the failure detection unit cannot detect and judge a failure of the bypass valve, so an unexpected mixed temperature Tm is detected relative to the set temperature Ts. In this case, it is only necessary to determine that there is an abnormality, and the advantage of Patent Document 1 is that it is only possible to instruct repair personnel to replace the bypass valve.

In order to solve the problem of Patent Document 1, the present embodiment uses a flow rate detector that detects the flow rate passing through the water heater, and the FF control unit is based on the sensor outputs of the flow rate detector and the incoming water temperature detector. The combustion power of the gas burner 13 is feedforward controlled by the capacity control device so that the temperature of hot water discharged from the hot water supply device becomes the set temperature Ts. With such a configuration, a failure occurs in the bypass valve, and even if Qc/Qh=α(N)=1, Qc/Qh=α(N)=0.2 Even when /Qh=α(N)=5, the only difference is the temperature of hot water discharged from the heat exchanger, and the temperature of hot water supplied from the water heater is the set temperature Ts. Therefore, it was possible to reliably prevent hot water from being discharged.

However, in the failure confirmation test of the bypass valve, the inventor of the present application changed Qc / Qh to the extent that hot water could not be discharged from the heat exchanger (for example, Qh was extremely reduced to 0). The supply of hot water is extremely small and tries to reach the mixing temperature. However, in the next instant, steam was generated at an explosive speed, and with that energy, the supply of hot water from the heat exchanger was extremely increased and decreased. It was presumed that such an event had occurred.

In this embodiment, hot water is safely discharged in a steady state (a state in which hot water is produced no matter how high the temperature is in the heat exchanger), that is, the FF control unit detects the flow rate passing through the water heater. In equipment and control where feedforward control is performed based on the flow rate detector, the incoming water temperature detector, and the set temperature Ts, even if the bypass valve fails, steam is generated in the heat exchanger, and the energy is , the phenomenon that the supply of hot water from the heat exchanger is extremely increased or decreased, and the degree of failure of the bypass valve is to be detected in an extreme failure state.

As a method for grasping such an extreme failure state, the inventors of the present application first tried to use the temperature gradient of the heat exchange hot water temperature for bypass servo open failure detection. When the temperature of the heat-exchanged hot water rapidly increased, the amount of heat exchange decreased due to the open failure of the bypass servo, and it was determined that the temperature had risen, and combustion was stopped. However, the following points were pointed out as problems.
1. There is a usage condition in which the temperature of the heat exchange outlet water rises slowly and an abnormality cannot be detected.
2. Immediately after hot water is discharged in an abnormal state, the heat exchanger temperature transitions to some extent the same as normal hot water, so an abnormality may not be detected before hot water is discharged at a high temperature.

In other words, if a sudden boiling phenomenon (bumping) occurs while water is being boiled in a pot, the temperature of the heat exchanged hot water may rise sharply, but usually small bubbles are generated at the bottom of the pot. After that, the phenomenon of disappearing, appearing and disappearing continues, and after that stage, the bubbles that are formed eventually become larger, the time for the bubbles to disappear becomes longer, and the bubbles reach the surface of the liquid, and boiling begins. That is, it is presumed that the total volume of the hot water and air bubbles in the heat exchanger gradually increases, and steam rushes in after boiling begins. The total volume of hot water and bubbles (small bubbles that disappear quickly) in the heat exchanger seems to gradually increase before the steam rushes in.

In other words, the phenomenon in which the amount of hot water discharged from the hot water supply device (flow rate x (outflow temperature - inlet water temperature)) gradually increases with respect to the amount of heat given (flow rate x (set temperature Ts - inlet water temperature)) occurs before the steam rushes in. It seems to occur in stages. Therefore, when the condition is (flow rate x (set temperature Ts - incoming water temperature)) << output hot water heat amount (flow rate x (output hot water temperature - incoming water temperature)), it is assumed that an abnormality has occurred and is detected as a preliminary step for steam to rush in. Although it seemed possible, it turned out that an accurate judgment could not be made for the following reasons. For example, at the start of combustion, heat must be stored in the heat exchanger itself (copper) (flow rate x (set temperature Ts - incoming water temperature)) >> discharged hot water heat amount (flow rate x (external hot water temperature - incoming water temperature)) Subsequently, (flow rate×(set temperature Ts−incoming water temperature))=heat amount of outlet hot water (flow rate×(outgoing hot water temperature−incoming water temperature)).

At this time, if Qc/Qh = α(N) = 1, for example, when Qc/Qh = α(N) = 0.2, the hot water being produced in the heat exchanger, or , a large amount of hot water is temporarily supplied from the outlet of the heat exchanger to the mixing temperature sensor, and the low-temperature hot water newly made in the heat exchanger reaches the mixing temperature sensor. −Inlet water temperature)) <<Outlet hot water heat amount (Flow rate×(Outlet hot water temperature−Inlet water temperature)) occurs.

In other words, it cannot be said that there is an abnormality simply because the state of (flow rate×(set temperature Ts−incoming water temperature))<<heat amount of discharged hot water (flow rate×(outgoing hot water temperature−incoming water temperature)) has occurred. Therefore, the inventors of the present application have determined the allowable operating range of Qc/Qh = α (N) and (flow rate x (set temperature Ts - incoming water temperature)) within the operating range This embodiment detects that the degree of failure of the bypass valve is in an extreme failure state (outside the allowable operating range=a state greatly deviating from the bypass ratio indicated value Bpnow) based on whether the temperature is the temperature)). rice field.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims. Some of the configurations of the above embodiments may be omitted, or may be arbitrarily combined in a manner different from the above.

In the above description, if the value obtained by subtracting the bypass ratio instruction value Bpnow from the bypass ratio calculation value Bpcalc is equal to or greater than the bypass ratio threshold value Bpth, the determination unit 132 determines whether the hot water supply latent heat exchanger 105 and the hot water supply heat from the inlet pipe 204 Although it is determined that the flow rate of the water led to the exchanger 106 is abnormal, another mode may be used. For example, when bypass ratio calculated value Bpcalc is equal to or greater than a predetermined threshold, it may be determined that the flow rate of water led from inlet pipe 204 to hot water supply latent heat exchanger 105 and hot water supply heat exchanger 106 is abnormal.

101 Hot water supply device 103 First burner 104 Second burner 105 Hot water supply latent heat exchanger 106 Hot water supply heat exchanger 119 Heat exchange thermistor DESCRIPTION OF SYMBOLS 120... Water supply thermistor 121... Water quantity sensor 122... Bypass servo 123... Hot water supply thermistor 130... Control device 131... Control part 132... Judgment part 133 204 Inlet pipe 207 Outlet pipe 211 Bypass pipe Bpcalc Bypass ratio calculated value Bpnow Bypass ratio indicated value Bpth Bypass ratio threshold

Claims (7)

burner and
a heat exchanger that heats water flowing therein with heat generated by the burner;
an inlet pipe supplying cold water to the heat exchanger;
an outlet pipe for discharging hot water from the heat exchanger;
a bypass pipe that connects the inlet pipe and the outlet pipe and guides the low-temperature water from the inlet pipe to the outlet pipe without passing through the heat exchanger;
a feed water temperature detection unit that detects the temperature of the low-temperature water supplied to the inlet pipe;
an outlet hot water temperature detection unit that detects the temperature of the high-temperature water discharged from the outlet pipe;
a hot water supply temperature detection unit that detects the temperature of mixed water obtained by mixing the high-temperature water discharged from the outlet pipe and the low-temperature water guided from the bypass pipe to the outlet pipe;
a regulating valve that adjusts the flow rate of the low-temperature water guided from the inlet pipe to the bypass pipe;
a control unit that controls the regulating valve;
The temperature of the mixed water detected by the hot water supply temperature detector at a predetermined time, the temperature of the high-temperature water detected by the outlet hot water temperature detector at a first time that is one hour before the predetermined time, and the water supply temperature a determination unit that determines an abnormality in the flow rate of the low-temperature water guided to the heat exchanger based on the temperature of the low-temperature water detected by the detection unit at a second time that is two hours before the predetermined time; prepared,
The first time is a time required for the high-temperature water that has passed through the hot water supply temperature detection unit to reach the hot water supply temperature detection unit,
The hot water supply apparatus, wherein the second time is a time required for the low-temperature water that has passed through the water supply temperature detection section to reach the hot water supply temperature detection section through the bypass pipe. The determination unit determines an abnormality in the flow rate of the low-temperature water led to the heat exchanger based on the bypass ratio calculated value,
The bypass ratio calculated value is a first temperature obtained by subtracting the temperature of the mixed water detected by the hot water supply temperature detector at the predetermined time from the temperature of the high-temperature water detected by the outlet hot water temperature detector at the first time. and a value obtained by dividing the temperature of the mixed water detected by the hot water supply temperature detector at the predetermined time by a second temperature obtained by subtracting the temperature of the low-temperature water detected by the water supply temperature detector at the second time from the temperature of the mixed water detected by the hot water supply temperature detector at the predetermined time. The water heater according to claim 1, characterized by: The determination unit determines that the flow rate of the low-temperature water is abnormal when a value obtained by subtracting the bypass ratio instruction value from the bypass ratio calculation value is equal to or greater than a predetermined threshold,
The bypass ratio indicated value is a value calculated from the opening degree of the adjustment valve, and is a ratio of the flow rate of the low-temperature water led to the bypass pipe to the flow rate of the low-temperature water supplied to the heat exchanger. 3. The hot water supply apparatus according to claim 2, wherein the value is an indicated value. 2. The control unit controls to stop the combustion operation by the burner when the determination unit determines that the flow rate of the low-temperature water led to the heat exchanger is abnormal. The water heater according to any one of claims 3 to 4. The adjustment valve can adjust the opening degree by rotating a stepping motor,
The control unit controls the stepping motor to a predetermined initial state when the determination unit determines that the flow rate of the low-temperature water led to the heat exchanger is abnormal. The water heater according to any one of claims 1 to 4. The temperature of the mixed water detected by the hot water supply temperature detection unit at the predetermined time, the temperature of the high-temperature water detected by the outlet hot water temperature detection unit at the first time, The hot water supply apparatus according to any one of claims 1 to 5, wherein abnormality of the regulating valve is determined based on the detected temperature of the low-temperature water. A control method for a water heater,
The water heater is
burner and
a heat exchanger that heats water flowing therein with heat generated by the burner;
an inlet pipe supplying cold water to the heat exchanger;
an outlet pipe for discharging hot water from the heat exchanger;
a bypass pipe that connects the inlet pipe and the outlet pipe and guides the low-temperature water from the inlet pipe to the outlet pipe without passing through the heat exchanger;
a feed water temperature detection unit that detects the temperature of the low-temperature water supplied to the inlet pipe;
an outlet hot water temperature detection unit that detects the temperature of the high-temperature water discharged from the outlet pipe;
a hot water supply temperature detection unit that detects the temperature of mixed water obtained by mixing the high-temperature water discharged from the outlet pipe and the low-temperature water guided from the bypass pipe to the outlet pipe;
a regulating valve that adjusts the flow rate of the low-temperature water guided from the inlet pipe to the bypass pipe;
The temperature of the mixed water detected by the hot water supply temperature detector at a predetermined time, the temperature of the high-temperature water detected by the outlet hot water temperature detector at a first time that is one hour before the predetermined time, and the water supply temperature a determination step of determining an abnormality in the flow rate of the low-temperature water led to the heat exchanger based on the temperature of the low-temperature water detected by the detection unit at a second time that is two hours earlier than the predetermined time; prepared,
The first time is a time required for the high-temperature water that has passed through the hot water supply temperature detection unit to reach the hot water supply temperature detection unit,
The method of controlling a hot water supply apparatus, wherein the second time is a time required for the low-temperature water that has passed through the water supply temperature detection section to reach the hot water supply temperature detection section through the bypass pipe.

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