JP2015187511A - circulation type water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circulation type water heater capable of stopping a circulation pump by detecting hot water tapping start with a simple configuration and with good accuracy.SOLUTION: A circulation path is formed by branching a recirculation passage before a hot water tap from hot water supply piping connected to the hot water tap from a circulation type water heater, and by connecting it to water supply piping of the circulation type water heater via recirculation piping. While hot water is not being tapped, hot water in a circulation path is circulated by using a circulation pump. Also, at least one of the recirculation passage and the recirculation piping, a resistance part with respect to the flow of the hot water is provided. Thus, at the hot water tapping start time, a load on the circulation pump and a flow rate of the hot water flowing in a heat exchanger change greatly, and by detecting them, an operation of the circulation pump can be stopped by detecting the hot water tapping start at the hot water tap with good accuracy without adding a new sensor and the like.

Description

  The present invention relates to a circulating hot water supply apparatus having a function of maintaining hot water in a hot water supply passage at an appropriate temperature by circulating hot water in the hot water supply passage through a heat exchanger when hot water supply is stopped.

  2. Description of the Related Art A hot water supply apparatus that uses hot water heated by a heat exchanger from a hot water supply curan or the like through a hot water supply passage is widely used. In this hot water supply apparatus, in order to avoid that the hot water in the hot water supply passage is cooled during the stop of hot water supply, a reflux passage is formed to return the hot water in the hot water supply passage to the heat exchanger from the front side of the hot water supply curan. Circulating hot water using a circulation pump is also performed. A hot water supply apparatus (circulation type hot water supply apparatus) having such a reflux passage can circulate hot water in the hot water supply passage and keep it warm in a heat exchanger while hot water supply is stopped. Hot water can be discharged.

  In addition, since hot hot water generated by the heat exchanger is supplied after starting hot water from a hot water supply curan or the like, the hot water in the hot water supply passage is not cooled without circulating hot water with a circulation pump. Therefore, it is desirable to stop the operation of the circulation pump after starting the hot water from the viewpoint of suppressing the power consumption by driving the circulation pump and improving the durability of the circulation pump.

  Therefore, the flow rate of hot water passing through the heat exchanger and the flow rate of hot water returned from the return passage are measured, and if the difference between these flow rates becomes large, it is judged that the hot water has started and circulated. A technique for stopping the pump has been proposed (Patent Document 1). Alternatively, when the hot water is discharged from the hot water supply curan, water corresponding to that amount is replenished from the water pipe and the temperature of the hot water decreases, so if this temperature decrease is detected, it is determined that the hot water has started and circulated. A technique for stopping the pump has also been proposed (Patent Document 2).

JP 2007-263403 A Japanese Patent No. 3605816

  However, the proposed technique described above has a problem that it is difficult to ensure sufficient detection accuracy while the structure becomes complicated because it is necessary to add a new sensor. For example, in the technique of the above-mentioned Patent Document 1, a flow rate sensor that detects the flow rate of the flowing hot water is newly required. Nevertheless, since it is necessary to determine the flow rate difference between the two sensors, it is easily affected by variations in characteristics between the sensors, and it is difficult to ensure sufficient detection accuracy. Further, in the technique of Patent Document 2 described above, when the temperature of tap water becomes warm, such as in summer, for example, the temperature drop at the time of hot water is reduced, so the detection accuracy is lowered. When trying to optimize the temperature detection position in order to improve the detection accuracy even a little, it becomes necessary to add a dedicated temperature sensor in addition to the existing temperature sensor, and the structure becomes complicated.

  The present invention has been made in response to the above-described problems in the prior art, and provides a circulation type hot water supply apparatus capable of detecting the start of hot water with a simple structure and with high accuracy and stopping the circulation pump. Objective.

In order to solve the above-described problems, the circulation type hot water supply apparatus of the present invention employs the following configuration. That is,
It is generated by a burner that burns fuel gas, a heat exchanger that heats hot water passing through the inside with combustion exhaust gas generated by the burner, a water supply pipe that supplies clean water to the heat exchanger, and the heat exchanger. A hot water supply pipe for supplying hot water toward the outlet tap, and a reflux passage branched in the middle of the hot water supply passage connecting the hot water supply pipe and the outlet tap, and the hot water in the return passage is connected to the water supply pipe. Circulation provided with a reflux pipe for reflux, and a circulation pump for circulating hot water in a circulation path formed by the heat exchanger, the hot water supply pipe, the hot water supply passage, the reflux passage, the reflux pipe and the water supply pipe In the type hot water supply device,
At least one of the recirculation passage or the recirculation pipe is provided with a resistance portion against a flow of hot water circulating in the circulation path.

  In such a circulation type hot water supply apparatus of the present invention, the hot water supplied from the heat exchanger to the hot water tap through the hot water supply pipe and the hot water supply passage is recirculated by operating the circulation pump even when the hot water is not discharged from the hot water tap. It can be made to recirculate | reflux to a heat exchanger from a channel | path via a reflux piping and a water supply piping. Then, when hot water discharge is started from the hot water tap while the circulation pump is operated, the flow rate of the hot water flowing back through the return passage and the return pipe decreases. Here, although the detailed mechanism will be described later, if a resistance portion is provided in at least one of the reflux passage and the reflux pipe, the load of the circulation pump caused by the decrease in the flow rate of hot water refluxed from the reflux path and the reflux pipe The flow rate of hot water flowing through the heat exchanger changes greatly. Therefore, if this is detected, it is possible to accurately detect the start of the hot water at the hot water tap and stop the operation of the circulation pump without adding a new sensor or the like.

  In the above-described circulating hot water supply apparatus of the present invention, a circulation pump is provided in either the reflux passage or the reflux pipe, and the resistance portion is located downstream of the circulation pump and the position where the reflux pipe joins the water supply pipe. It is good also as providing between.

  If a circulation pump is provided in either the reflux passage or the reflux pipe, the circulation pump does not become a resistance when hot water is discharged from the tap. Further, if the resistance portion is provided downstream from the circulation pump and between the return pipe and the position where the return pipe joins the water supply pipe, the resistance section also becomes resistance when hot water is discharged from the tap. There is nothing. In addition, by providing the resistance portion on the downstream side of the circulation pump, it becomes difficult for the circulation pump to become negative pressure due to the resistance at the resistance portion, so that the performance of the circulation pump can be sufficiently exhibited.

  Moreover, in the circulation type hot water supply apparatus of the present invention described above, a resistance unit capable of changing the magnitude of resistance to the flow of hot water circulating in the circulation path may be used.

  If it carries out like this, the influence by the difference in the piping state between a circulation type hot-water supply apparatus and a hot water tap can be suppressed by adjusting the magnitude | size of resistance of a resistance part. As a result, the circulation pump can be stopped by accurately detecting the start of the hot water at the hot water tap without being affected by the piping state.

  Further, the above-described circulation type hot water supply apparatus of the present invention includes a control unit that controls the operation of the circulation pump, and detects that the load on the circulation pump has decreased during the operation of the circulation pump and stops the circulation pump. It is good.

  Since the controller controls the operation of the circulation pump, this can be detected if the load on the circulation pump decreases. Therefore, if it carries out like this, it will become possible to detect the hot-water-start start with a hot-water tap accurately, and to stop a circulation pump, only by adding a resistance part, without adding any new sensors.

  The above-described circulation type hot water supply apparatus of the present invention includes a control unit that controls the operation of the circulation pump and a flow rate sensor that detects the flow rate of the hot water flowing into the heat exchanger, and the flow rate during the operation of the circulation pump. When the increase is detected, the circulation pump may be stopped.

  The hot water supply device is provided with a flow rate sensor that detects the flow rate of hot water flowing into the heat exchanger, and the output of the flow rate sensor is input to the control unit. Therefore, if it carries out like this, it will become possible to detect the hot-water-start start with a hot-water tap accurately, and to stop a circulation pump, only by adding a resistance part, without adding any new sensors.

It is explanatory drawing which showed the whole structure of the hot water supply system 1 provided with the circulation type hot water supply apparatus 10 of a present Example. It is explanatory drawing which showed the principle in which the circulation type hot water supply apparatus 10 of a present Example detects the start of hot water discharge. It is a flowchart of the process which the circulation type hot water supply apparatus 10 of a present Example detects the start of hot water discharge, and stops a circulation pump. It is explanatory drawing about the effect which suppresses the difference in the piping state from the circulation type hot water supply apparatus 10 to the hot water tap 30. It is explanatory drawing about the resistance part 24 of the modification which can change the magnitude | size of resistance.

  FIG. 1 is an explanatory diagram showing an overall configuration of a hot water supply system 1 including a circulating hot water supply apparatus 10 according to the present embodiment. As shown in the figure, the circulating hot water supply apparatus 10 includes a burner 11 that burns fuel gas supplied from a gas pipe 5, a combustion fan 12 that supplies combustion air toward the burner 11, and combustion generated in the burner 11. A heat exchanger 13 for exchanging heat with exhaust gas, a water supply pipe 4 for supplying clean water from a water pipe (not shown) to the heat exchanger 13, and a hot water supply pipe for discharging hot water heated by the heat exchanger 13 20.

  The hot water supply pipe 20 is connected to the hot water supply passage 31 outside the circulation type hot water supply apparatus 10, and is connected to the hot water tap 30 through the hot water supply passage 31. The hot water tap 30 may be a hot water supply curan or a hot water shower. A plurality of hot water taps 30 may be provided. A reflux passage 32 branches off from the hot water supply passage 31 at a branch point 33 immediately before the hot water tap 30, and the other end of the branched return passage 32 is connected to the return piping 21 outside the circulating hot water supply device 10. ing. The reflux pipe 21 is connected to the water supply pipe 4 via a circulation pump 22. Therefore, the heat exchanger 13, the hot water supply pipe 20, the hot water supply path 31, the reflux path 32, the reflux pipe 21, and the water supply pipe 4 form a circulation path. Further, a check valve 25 is provided between the circulation pump 22 and the water supply pipe 4 for preventing the reverse flow of clean water from the water supply pipe 4 toward the circulation pump 22. For this reason, by operating the circulation pump 22, hot water in the circulation path can be circulated in one direction (counterclockwise in the illustrated example).

  Further, in the circulating hot water supply apparatus 10 of the present embodiment, the resistance portion 24 that is resistant to the flow of hot water is provided between the circulation pump 22 and the junction 23 where the reflux pipe 21 and the water supply pipe 4 join. Is provided. In the present embodiment, description will be made on the assumption that an orifice is provided as the resistance portion 24. However, the resistance portion 24 is not limited to the orifice as long as it is resistant to the flow of hot water, for example, a fine mesh or a mesh such as a fiber. It is also possible to use a thin tube or the like. In the circulation type hot water supply apparatus 10 of the present embodiment, it is possible to immediately detect that the hot water tap has been started by the hot water tap 30 by providing such a resistance portion 24. The reason for this will be described in detail later.

  In the present embodiment, the circulation pump 22 and the resistance unit 24 are described as being provided in the middle of the reflux pipe 21 (that is, inside the circulation hot water supply apparatus 10), but in the middle of the reflux passage 32 (that is, the circulation). It can also be provided outside the hot water supply apparatus 10. Further, in this embodiment, the description will be made on the assumption that the resistance portion 24 is provided on the downstream side of the circulation pump 22, but it is also possible to provide the resistance portion 24 on the upstream side of the circulation pump 22 from the mechanism described later. It is.

  Further, in the circulating hot water supply apparatus 10 of the present embodiment, as in the conventional general circulating hot water supply apparatus, in the middle of the water supply pipe 4, tap water supplied to the heat exchanger 13 or recirculated hot water is provided. A flow rate sensor 7 that measures the flow rate, a flow rate control valve 6 that controls the flow rate of the hot water, a temperature sensor 8 that detects the temperature of the hot water supplied to the heat exchanger 13, and hot water that flows out of the heat exchanger 13. A temperature sensor 9 for detecting the temperature is also provided. Outputs from the flow rate sensor 7 and the temperature sensors 8 and 9 are input to the control unit 50, and the control unit 50 controls operations of the flow rate control valve 6 and the circulation pump 22.

  FIG. 2 is an explanatory view of the principle that the circulating hot water supply apparatus 10 of the present embodiment detects that the hot water has started from the hot water tap 30. FIG. 2A shows a state in which the hot water tap 30 is not discharged, and FIG. 2B shows a state immediately after the hot water from the hot water tap 30 is started. In FIG. 2, parts that are not related to the explanation are indicated by broken lines or omitted in order to avoid complicated illustration.

  As shown in FIG. 2 (a), when the hot water tap 30 has not been tapped, the circulation pump 22 is in operation, and as shown by the hatched arrows in the figure, The hot water from the heat exchanger 13 is circulated to the heat exchanger 13 via the hot water supply pipe 20, the hot water supply passage 31, the reflux passage 32, the reflux pipe 21, and the water supply pipe 4. Of course, when hot and cold water circulates, a flow path resistance is generated, so that a load corresponding to the flow path resistance is applied to the circulation pump 22. Further, in the circulating hot water supply apparatus 10 of the present embodiment, since the resistance portion 24 is provided in the middle of the reflux pipe 21 (or the reflux passage 32), the load applied to the circulation pump 22 increases accordingly. Since there is no water outlet while the tap tap 30 is not opened, new tap water is not supplied from the water supply pipe 4. However, the water pressure from the water pipe (not shown) is applied to the entire circulation path.

  When the hot water tap 30 is opened from this state, hot water flows out from the hot water tap 30 at that moment. Moreover, immediately after opening the tap tap 30, the circulation pump 22 is still operating. Therefore, as indicated by the hatched arrows in FIG. 2B, hot water returns from the branch point 33 before the tap tap 30 to the water supply pipe 4 through the return passage 32 and the return pipe 21. To do. However, since hot water is flowing out from the hot water tap 30, the flow rate of hot water flowing back from the branch point 33 is smaller than the state before the hot water flows out (see FIG. 2A). Further, the total amount of hot water in the circulation path does not change regardless of whether or not there is an outflow from the hot water tap 30, so that new water as much as the flow rate flowing out from the hot water tap 30 is supplied from the water supply pipe 4. An arrow shown in white in FIG. 2B represents a state in which new water is supplied from the water supply pipe 4. Therefore, the flow rate of hot water measured by the flow rate sensor 7 is a flow rate obtained by adding the flow rate of new water supplied from the water supply pipe 4 to the flow rate of hot water returning from the return pipe 21. Then, after the hot water of this flow rate is heated by the heat exchanger 13, the hot water is supplied to the hot water tap 30 through the hot water supply pipe 20 and the hot water supply passage 31.

  Here, when FIG. 2 (a) showing the state before the start of pouring is compared with FIG. 2 (b) showing the state immediately after the start of pouring, all the hot water flows in all the circulation paths in FIG. 2 (a). In contrast to the circulation, in FIG. 2 (b), the hot water that has not been discharged from the hot water tap 30 is merely returned to the water supply pipe 4. That is, it is not necessary to recirculate the hot water discharged from the hot water tap 30 from the recirculation passage 32 to the water supply line 4 via the recirculation line 21, so that the load of the circulation pump 22 is equivalent to the flow resistance between them. Has been reduced. Therefore, the load on the circulation pump 22 is reduced immediately after the hot water tap 30 is started. In particular, in the circulating hot water supply apparatus 10 according to the present embodiment, the resistance portion 24 is provided in the reflux passage 32 or the reflux pipe 21, so that the load due to the fact that the hot water does not need to reflux the reflux path 32 and the reflux pipe 21. The decrease of becomes larger.

  Moreover, the flow rate of the hot water detected by the flow sensor 7 also changes. That is, in FIG. 2A, the flow rate of hot water detected by the flow sensor 7 is equal to the flow rate of hot water circulated by the circulation pump 22. However, in FIG. 2B, the flow rate is obtained by adding the flow rate of tap water supplied from the water supply pipe 4 (and hence the flow rate of hot water flowing out of the tap tap 30) to the flow rate of hot water passing through the circulation pump 22. . Therefore, when hot water is started at the hot water tap 30, the flow rate of hot water detected by the flow sensor 7 increases immediately after that. In addition, the reduction in the load of the circulation pump 22 is nothing but the ease of pumping hot water to the circulation pump 22, so that the flow rate of hot water pumped by the circulation pump 22 increases as the load decreases. That is, the flow rate of hot water passing through the circulation pump 22 in FIG. 2B is obtained by subtracting the flow rate of hot water flowing out of the tap tap 30 from the flow rate of hot water passing through the circulation pump 22 in FIG. Also grows. For this reason, when the hot water tap 30 is started, the increase in the flow rate detected by the flow rate sensor 7 is further increased.

  From the above, during the operation of the circulation pump 22, it is possible to immediately detect the start of the hot water at the hot water tap 30 by monitoring the load of the circulation pump 22 or the output of the flow rate sensor 7. In the circulating hot water supply apparatus 10 of the present embodiment, paying attention to such a mechanism, the operation of the circulating pump 22 is stopped.

  FIG. 3 is a flowchart of processing in which the circulating hot water supply apparatus 10 according to the present embodiment detects the start of hot water discharge at the hot water tap 30 and stops the operation of the circulation pump 22. This process is a process that starts after the control unit 50 operates the circulation pump 22.

  As shown in the figure, in the circulation pump stop process, it is determined whether or not the flow rate detected by the flow rate sensor 7 has increased (S10). If the flow rate has not increased (S10: no), it is determined whether or not the load on the circulation pump 22 has decreased (S11). The load on the circulation pump 22 can be detected by various methods. For example, since the load of the circulation pump 22 and the drive current are in a substantially proportional relationship, a decrease in the load can be detected by detecting a decrease in the drive current of the circulation pump 22. Alternatively, since the rotational speed of the circulation pump 22 increases if the load decreases suddenly, a decrease in the load of the circulation pump 22 can be detected by detecting an increase in the rotational speed.

  If the load on the circulation pump 22 has not decreased (S11: no), the process returns to the top of the process and determines again whether the flow rate of the flow rate sensor 7 has increased (S10). If the flow rate of the flow rate sensor 7 has increased (S10: yes) or the load of the circulation pump 22 has decreased (S11: yes) while repeating such operations, the hot water starts from the hot water tap 30. Therefore, the operation of the circulation pump 22 is stopped (S12), and the circulation pump stop process in FIG. 3 is terminated. Here, for convenience of explanation, both the flow rate of the flow rate sensor 7 and the load of the circulation pump 22 are monitored, and when either an increase in flow rate or a decrease in load is detected, the circulation pump 22. However, only one of them may be monitored.

  Thus, in the circulation type hot water supply apparatus 10 of the present embodiment, the circulation pump 22 can be detected by detecting the start of the hot water tap 30 without providing a new sensor by simply providing the resistance portion 24 in the reflux passage 32 or the reflux pipe 21. Can be stopped. Moreover, since the circulation pump 22 is controlled by the control part 50, even when detecting the load of the circulation pump 22, the start of the hot water tap 30 can be detected without providing a new sensor.

  Further, as illustrated in FIG. 1 or FIG. 2, if the resistance portion 24 is provided on the downstream side of the circulation pump 22, the circulation pump 22 is less likely to be negative pressure than the case where the resistance portion 24 is provided on the upstream side. Therefore, the possibility that the performance of the circulation pump 22 may be reduced can be suppressed.

  In addition, the resistance portion 24 only needs to be provided in the reflux passage 32 or the reflux piping 21, and does not need to be provided in the water supply pipe 4, the hot water supply pipe 20, or the hot water supply passage 31. After the circulation pump 22 is stopped, the resistance portion 24 does not become hot water resistance. For this reason, the resistance part 24 can be a resistor having a relatively large value. Normally, the flow rate of hot water circulated by the circulation pump 22 is set to a relatively small flow rate so that the hot water in the circulation path can be kept at an appropriate temperature while the hot water tap 30 is not discharged. When the hot water is started at 30, the load on the circulation pump 22 may not be significantly reduced. However, if the resistance portion 24 has a relatively large resistance, the load on the circulation pump 22 accompanying the start of the hot water at the hot water tap 30 can be greatly reduced, so that the start of the hot water can be accurately detected. Become.

  Further, if the resistance at the resistance portion 24 is set to a relatively large value, the start of the hot water discharge at the hot water tap 30 can be started without being affected by the difference in the piping path or the length of the hot water tap 30 from the circulating hot water supply device 10. It can also be detected with high accuracy. For example, FIG. 4 illustrates a case where hot water is supplied to a hot water tap 30 far from the circulating hot water supply apparatus 10. In such a case, the hot water supply passage 31 and the recirculation passage 32 from the circulation type hot water supply apparatus 10 to the hot water tap 30 become longer, and the number of bends in the middle increases. For this reason, even if the hot water tap 30 is started in the same manner, the amount of decrease in the load of the circulation pump 22 or the flow rate sensor 7 is different between the case illustrated in FIG. 1 or FIG. 2 and the case illustrated in FIG. The amount of increase in the flow rate changes at this point, which is an obstacle to accurately detecting the start of hot water.

  On the other hand, if the resistance in the resistance portion 24 is set to a relatively large value, the ratio of the resistance of the piping portion from the circulating hot water supply device 10 to the hot water tap 30 in the resistance of the entire circulation path is reduced. be able to. For this reason, it becomes difficult to receive the influence by the difference in piping state, and it becomes possible to detect the start of hot water with high accuracy.

  In the above-described embodiments, the resistance portion 24 has been described as having a fixed resistance value. However, the resistance value in the resistance unit 24 may be changeable. For example, as illustrated in FIG. 5A, the resistance portion 24 is formed by narrowing the passage of the reflux pipe 21 with a plurality of members 24 a, and a part of the member 24 a is made movable so that the resistance portion 24 is formed. It is also possible to change the value of the resistance. Alternatively, as illustrated in FIG. 5B, the resistance portion 24 is formed by providing the baffle plate 24 b in the passage of the reflux pipe 21, and the baffle plate 24 b can be rotated to thereby improve the resistance of the resistance portion 24. The value of may be changeable.

  In this way, by appropriately adjusting the resistance in the resistance portion 24 in accordance with the difference in resistance in the piping portion from the circulation type hot water supply apparatus 10 to the hot water tap 30, the tap water is not affected by the piping state. It is possible to accurately detect the start of the hot water at the stopper 30 and stop the circulation pump 22.

  As mentioned above, although the circulation type hot-water supply apparatus 10 of a present Example was demonstrated, this invention is not limited to said Example, In the range which does not deviate from the summary, it can be implemented with a various aspect. For example, in the above-described embodiment, the resistance portion 24 has been described as being provided at one location, but the resistance portion 24 may be provided at a plurality of locations in the reflux passage 32 or the reflux pipe 21.

1 ... Hot water supply system, 4 ... Water supply piping, 5 ... Gas piping,
6 ... Flow control valve, 7 ... Flow sensor, 8,9 ... Temperature sensor,
10: Circulating water heater, 11 ... Burner, 12 ... Combustion fan,
13 ... heat exchanger, 20 ... hot water supply pipe, 21 ... reflux pipe,
22 ... circulation pump, 24 ... resistor, 25 ... check valve,
30 ... Hot water tap, 31 ... Hot water supply passage, 32 ... Reflux passage,
50: Control unit.

Claims (5)

It is generated by a burner that burns fuel gas, a heat exchanger that heats hot water passing through the inside with combustion exhaust gas generated by the burner, a water supply pipe that supplies clean water to the heat exchanger, and the heat exchanger. A hot water supply pipe for supplying hot water toward the outlet tap, and a reflux passage branched in the middle of the hot water supply passage connecting the hot water supply pipe and the outlet tap, and the hot water in the return passage is connected to the water supply pipe. Circulation provided with a reflux pipe for reflux, and a circulation pump for circulating hot water in a circulation path formed by the heat exchanger, the hot water supply pipe, the hot water supply passage, the reflux passage, the reflux pipe and the water supply pipe In the type hot water supply device,
At least one of the recirculation passage or the recirculation pipe is provided with a resistance portion against the flow of hot water circulating in the circulation path. In the circulation type hot water supply apparatus according to claim 1,
The circulation pump is provided in either the return passage or the return pipe,
The said resistance part is provided in the downstream from the said circulation pump and between the position where the said return piping merges with the said water supply piping. The circulation type hot water supply apparatus characterized by the above-mentioned. In the circulation type hot water supply apparatus according to claim 1 or 2,
The said resistance part can change the magnitude | size of the resistance with respect to the flow of the hot water circulating through the said circulation path. The circulation type hot water supply apparatus characterized by the above-mentioned. In the circulation type hot water supply device according to any one of claims 1 to 3,
A control unit for controlling the operation of the circulation pump;
The circulating water heater is characterized in that the controller stops the circulating pump when detecting that the load of the circulating pump is reduced during the operation of the circulating pump. In the circulation type hot water supply device according to any one of claims 1 to 3,
A control unit for controlling the operation of the circulation pump;
A flow rate sensor for detecting the flow rate of hot water flowing into the heat exchanger,
The circulation type hot water supply apparatus, wherein the control unit stops the circulation pump when detecting that the flow rate detected by the flow rate sensor is increased during the operation of the circulation pump.

Images