water heater

Abstract

The present invention provides a water heater that can determine whether a person is entering or leaving the bathtub, even when the bath circulation circuit is switched to a drain discharge position connected to the drain discharge circuit using a switching mechanism to perform a drain discharge operation. [Solution] The water heater comprises a bath circulation circuit that circulates the bath water using a pump, a drain discharge circuit that discharges drain from the latent heat exchanger to the outside through a part of the bath circulation circuit, a switching means that switches the bath circulation circuit to a circulation position that communicates with the bathtub or to a drain discharge position that disconnects the bath circulation circuit from the bathtub and communicates with the drain discharge circuit, a water level sensor disposed in the bath circulation circuit that detects the water level in the bathtub, and a control unit. The control unit stores the water level before the drain discharge operation based on the detection result of the water level sensor, compares this stored water level with the water level after the drain discharge operation is completed, and determines whether a person is entering or leaving the bathtub during the drain discharge operation.

Description

Technical Field

[0001] The present invention relates to a water heater having a configuration for discharging drain generated in a latent heat exchanger to a bathroom or the like outside the water heater.

Background Art

[0002] Patent Document 1 describes a hot water supply device including a bath circulation circuit for circulating hot water in a bathtub by a pump and a drain discharge circuit for discharging drain from a latent heat exchanger through a part of the bath circulation circuit to the bathroom. The hot water supply device performs a drain discharge operation of discharging the drain to the bathroom by switching the bath circulation circuit to a drain discharge position in communication with the drain discharge circuit and non-communicating with the bathtub by a switching means. Further, Patent Document 2 describes a bath device provided with a water level sensor for detecting the water level of hot water in a bathtub in a bath circulation circuit, and determining that a person has taken a bath in the bathtub when the water level of the bathtub rises beyond a predetermined amount.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, for example, consider a configuration in which a water level sensor described in Patent Document 2 is provided in the bath circulation circuit of the hot water supply device of Patent Document 1 to determine whether a person has entered or exited the bathtub. However, in the hot water supply device of Patent Document 1, during the drain discharge operation, since the bath circulation circuit is switched to a drain discharge position in communication with the drain discharge circuit by the switching means and the bath circulation circuit and the bathtub become non-communicating, the water level of the bathtub cannot be detected. Therefore, during the drain discharge operation, the state of a person entering or exiting the bathtub cannot be recognized.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a water heater that can determine whether a person is entering or leaving the bathtub, even when the bath circulation circuit is switched to a drain discharge position that communicates with the drain discharge circuit by a switching means and a drain discharge operation is performed. [Means for solving the problem]

[0006] A water heater according to one aspect of the present invention is: A water heater comprising a bath circulation circuit that circulates bath water using a pump, a drain discharge circuit that discharges drain from a latent heat exchanger to the outside through a part of the bath circulation circuit, and a switching means that switches between a circulation position in which the bath circulation circuit is connected to the bathtub, and a drain discharge position in which the bath circulation circuit is not connected to the bathtub and is connected to the drain discharge circuit, wherein the water heater performs a drain discharge operation to discharge drain to the outside using the drain discharge circuit, The bath circulation circuit includes a water level sensor that detects the water level in the bathtub, and a control unit that determines whether a person enters or exits the bathtub based on the detection result of the water level sensor. The control unit is configured to store the water level before the drain discharge operation based on the water level sensor's detection result, and to compare this stored water level with the water level after the drain discharge operation is completed, in order to determine whether a person is entering or leaving the bathtub during the drain discharge operation.

[0007] With this configuration, by memorizing the water level before the drain discharge operation, the switching means can be used to switch the bath circulation circuit from a circulation position connected to the bathtub to a drain discharge position disconnected from the bathtub, and then compare it with the water level when the bath circulation circuit is switched back to a circulation position connected to the bathtub. Therefore, it is possible to suitably detect when a person enters or leaves the bathtub during a drain discharge operation when the bath circulation circuit is disconnected from the bathtub but connected to the drain discharge circuit.

[0008] Furthermore, in one embodiment of the present invention, the following configurations can be combined arbitrarily without contradiction.

[0009] In the aforementioned water heater, The water level before the drain discharge operation may be the water level from the time the instruction to start the drain discharge operation is given until the switching means is switched from the circulation position to the drain discharge position.

[0010] With this configuration, the water level just before the bath circulation circuit and the bathtub are disconnected can be obtained as the water level before the drain discharge operation, making it possible to determine with higher accuracy whether a person is entering or leaving the bathtub during the drain discharge operation.

[0011] In the aforementioned water heater, The water level after the completion of the drain discharge operation may be the water level after switching the switching means from the drain discharge position to the circulation position, operating the pump for a predetermined time, and a predetermined waiting time has elapsed after the pump has stopped operating.

[0012] With this configuration, even after the drain discharge operation is completed, the bath circulation circuit is filled with bath water and does not contain air or other contaminants, and the water level in the bathtub is stable. As a result, the water level can be obtained when the water level in the bathtub is stable, allowing for a more accurate determination of whether a person is entering or leaving the bathtub during the drain discharge operation.

[0013] In the aforementioned water heater, A drain tank that neutralizes and temporarily stores the condensate generated in the latent heat exchanger, It is equipped with a drain water level detector installed in the drain tank to detect the water level of the stored drain, The control unit, When the drain water level in the drain tank rises, the system instructs the start of the drain discharge operation, and the water level in the bathtub at this time is stored as the water level before the drain discharge operation. Switch the switching mechanism from the circulation position to the drain discharge position, and activate the pump. When the drain water level in the drain tank drops low, the pump stops operating. After passing a predetermined amount of clean hot water or water through the drain discharge circuit, The system may also include a configuration in which the switching mechanism is switched from the drain discharge position to the circulation position, and the water level in the bathtub after a predetermined waiting period has elapsed following the operation of the pump for a predetermined time is set to the water level after the drain discharge operation is completed.

[0014] This configuration allows the condensate generated in the latent heat exchanger to be discharged to the outside, and also allows for the effective detection of a person entering or leaving the bathtub while this condensate discharge operation is in progress. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing the overall configuration of a water heater according to an embodiment. [Figure 2] This flowchart explains the operation of bath entry / exit detection when drain discharge is performed during bathing. [Figure 3] This flowchart explains the operation of bath entry / exit detection when drain discharge is performed before bathing. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described below with reference to the accompanying drawings. The water heater 1 shown in Fig. 1 is a latent heat recovery type gas water heater equipped with a latent heat exchanger 10. In such a water heater 1, in the latent heat exchanger 10, the combustion exhaust gas is cooled by heat exchange for latent heat recovery and condensed to generate drain (condensed water). The water heater 1 of the present embodiment includes a bath circulation circuit 2 that circulates the hot water in the bathtub 40 by a pump 22, a drain discharge circuit 3 that discharges the drain generated in the latent heat exchanger 10 to the bathroom 4 through a part of the bath circulation circuit 2, and a switching valve 51 and a drain drainage switching valve 52 that are switching means for switching the bath circulation circuit 2 to a circulation position communicating with the bathtub 40 or to a drain discharge position where the bath circulation circuit 2 is not in communication with the bathtub 40 and is in communication with the drain discharge circuit 3. The water heater 1 is configured to perform a drain discharge operation of discharging the drain to the bathroom 4 by the drain discharge circuit 3. The water heater 1 is installed outdoors, and the bath circulation circuit 2 of the water heater 1 penetrates the outer wall of the house and the wall of the bathroom 4 and is drawn into the bathroom 4 and connected to the bathtub 40.

[0017] The water heater 1 includes a gas burner 60 that generates combustion exhaust gas, a fan 61 that supplies combustion air to the gas burner 60, and a hot water heat exchanger 7 and a bath heat exchanger 8 that absorb heat from the combustion exhaust gas to heat the hot water. A gas supply pipe 62 for supplying fuel gas is connected to the gas burner 60. The gas supply pipe 62 is provided with an original gas solenoid valve 63, a gas proportional valve 64, and a switching gas solenoid valve 65 in order from the upstream side. The hot water heat exchanger 7 and the bath heat exchanger 8 include a sensible heat exchanger 9 that recovers sensible heat from the combustion exhaust gas and a latent heat exchanger 10 that recovers latent heat from the combustion exhaust gas.

[0018] The water heater 1 includes a neutralizer 12 for neutralizing the drain water generated in the latent heat exchanger 10. The neutralizer 12 has a drain tank 13 for neutralizing the drain water and temporarily storing it. A drain introduction pipe 14 drawn from the drain water collection pan 11 disposed in the latent heat exchanger 10 is connected to the neutralizer 12. The drain water collection pan 11 collects the drain water generated in the latent heat exchanger 10 and discharges it into the drain introduction pipe 14. A drain discharge pipe 15 for discharging the stored drain water is connected to the drain tank 13, and a check valve 16 for preventing the backflow of the drain water to the drain tank 13 side is provided in the drain discharge pipe 15. A drain water level detector 17 for detecting the water level of the stored drain water is provided in the drain tank 13. The drain water level detector 17 has a high water level electrode 17a for detecting the drain water surface and detecting that the drain water is stored full in the drain tank 13, and a low water level electrode 17b for detecting the drain water surface and detecting that the drain water in the drain tank 13 has been discharged.

[0019] An inlet water pipe 71 and an outlet hot water pipe 72 are connected to the hot water heat exchanger 7. A water volume sensor 73, a feed water temperature sensor 74, and a water volume servo 75 are provided in the inlet water pipe 71 in order from the upstream side. A heat exchange temperature sensor 76 is provided on the upstream side of the outlet hot water pipe 72, and an outlet hot water temperature sensor 77 is provided on the downstream side.

[0020] A bath heat exchanger 8 is connected to a bath circulation circuit 2. The bath circulation circuit 2 includes a bath circulation return pipe 18 and a bath circulation supply pipe 19. One end portions of the bath circulation return pipe 18 and the bath circulation supply pipe 19 are connected to the bath heat exchanger 8, and the other end portions are connected to a circulation adapter 41 of the bathtub 40.

[0021] The bath circulation return pipe 18 is equipped with, in order from the bathtub 40 side, a bath return temperature sensor 21, a switching valve 51, a pump 22, a water level sensor 23, and a bath water flow switch 24. The switching valve 51 is connected to a drain outlet pipe 15 drawn from the drain tank 13 of the neutralizer 12. The pump 22 circulates the hot water in the bathtub 40 into the bath circulation circuit 2 through its operation. The water level sensor 23 detects the water level in the bathtub 40 by detecting the pressure inside the bathtub 40 through the bath circulation circuit 2. Based on the detection result of this water level sensor 23, it is possible to determine whether a person is entering or leaving the bathtub 40. The bath water flow switch 24 detects when hot water flows into the bath circulation circuit 2.

[0022] Furthermore, the bath circulation return pipe 18 is connected to the hot water filling pipe 25, which is drawn out from the hot water outlet pipe 72, between the switching valve 51 and the pump 22. The hot water filling pipe 25 is equipped with a hot water filling solenoid valve 26, check valves 27a and 27b, and a hot water volume sensor 28, in that order from the hot water outlet pipe 72 side.

[0023] The bath circulation supply pipe 19 is equipped with a drain drain switching valve 52 and a bath supply temperature sensor 29, in that order from the bathtub 40 side. The drain drain switching valve 52 is installed in the empty space between the wall of the bathroom 4 and the bathtub 40. A drain drain pipe 20 that discharges drain into the bathroom 4 is connected to the drain drain switching valve 52. The drain drain pipe 20 extends from the drain drain switching valve 52 to the drain outlet 43 of the waterproof pan 42 of the bathtub 40.

[0024] In this embodiment, in the bath circulation return pipe 18, the piping portion between the switching valve 51 and the bath heat exchanger 8 is referred to as the heat exchanger side return pipe 18a, and the piping portion between the switching valve 51 and the circulation adapter 41 of the bathtub 40 is referred to as the bathtub side return pipe 18b. In the bath circulation supply pipe 19, the piping portion between the drain drain switching valve 52 and the bath heat exchanger 8 is referred to as the heat exchanger side supply pipe 19a, and the piping portion between the drain drain switching valve 52 and the circulation adapter 41 of the bathtub 40 is referred to as the bathtub side supply pipe 19b.

[0025] The drain discharge circuit 3 consists of a drain outlet pipe 15, a heat exchanger side return pipe 18a, a heat exchanger side supply pipe 19a, and a drain drain pipe 20.

[0026] The switching valve 51 and the drain drain switching valve 52 are configured to switch between a circulation position in which the bath circulation circuit 2 is connected to the bathtub 40 and a drain discharge position in which the bath circulation circuit 2 is not connected to the bathtub 40 and is connected to the drain discharge circuit 3. Specifically, the switching valve 51 is configured to switch between a circulation position in which the bathtub side return pipe 18b and the heat exchanger side return pipe 18a are connected and a drain discharge position in which the drain outlet pipe 15 and the heat exchanger side return pipe 18a are connected. The drain drain switching valve 52 is configured to switch between a circulation position in which the bathtub side supply pipe 19b and the heat exchanger side supply pipe 19a are connected and a drain discharge position in which the drain drain pipe 20 and the heat exchanger side supply pipe 19a are connected.

[0027] The water heater 1 includes a control unit 30 that controls the operation of the water heater 1. The control unit 30 controls the switching operation of the switching valve 51 and the drain drain switching valve 52 to perform a drain discharge operation that discharges the drain stored in the drain tank 13 to the bathroom 4 via the drain discharge circuit 3. The control unit 30 also has a function configuration that determines whether a person has entered or left the bathtub 40 based on the detection result of the water level sensor 23. When the control unit 30 determines that a person has entered the bathtub 40, it turns on the bathing flag, and when it determines that a person has left the bath, it turns off the bathing flag. The memory unit of the control unit 30 stores this bathing flag information.

[0028] Furthermore, the water heater 1 is connected to a bathroom remote control 31 and a kitchen remote control 32 for remotely operating the water heater 1. The bathroom remote control 31 and kitchen remote control 32 may be equipped with notification means for notifying the status of a person entering and leaving the bathtub 40 in the bathroom 4. For example, a timer in the control unit 30 measures the time a person is bathing in the bathtub 40, and if it is determined that the person is still bathing after a predetermined time has elapsed, the bathroom remote control 31 and kitchen remote control 32 issue a notification. This allows the person in the bathroom 4 to be warned about prolonged bathing by the notification from the bathroom remote control 31, and allows a person outside the bathroom 4 to understand the bathing status of the person inside the bathroom 4 by the notification from the kitchen remote control 32, thereby preventing bathing accidents.

[0029] Incidentally, the decision of whether a person is entering or leaving the bathtub 40 is made based on the detection result of a water level sensor 23 installed in the bath circulation circuit 2, which detects the pressure inside the bathtub 40 through the bath circulation circuit 2. On the other hand, during drain discharge operation, the switching valve 51 and the drain drain switching valve 52 are switched to a drain discharge position that connects the bath circulation circuit 2 to the drain discharge circuit 3, and the bath circulation circuit 2 is not in communication with the bathtub 40. As a result, the water level sensor 23 cannot correctly detect the pressure inside the bathtub 40, and therefore cannot determine whether a person is entering or leaving the bathtub 40. However, in the water heater 1 of this embodiment, by storing the water level of the bathtub 40 before the drain discharge operation (first water level), it is possible to compare this first water level with the water level of the bathtub 40 after the drain discharge operation is completed (second water level), and as a result, it is possible to determine whether a person is entering or leaving the bathtub 40 during the drain discharge operation.

[0030] Next, the operation of the water heater 1 of this embodiment to determine whether to enter or exit the bath while draining is in operation will be described. The following describes the operation when draining is performed while bathing (Figure 2) and when draining is performed before bathing (Figure 3). These operations are performed by the control unit 30.

[0031] First, let's explain the case where the drain operation is performed while bathing. The flowchart in Figure 2 shows the process when a drain discharge operation is performed while bathing. As shown in Figure 2, in step S1, the water level detection result of the bathtub 40 is obtained and the current water level is calculated. The current water level is calculated by obtaining the detection result of the water level sensor 23 at regular time intervals (for example, every 500ms), and calculating the average value of the detection results of the water level sensor 23 obtained from the present to a certain time ago (for example, 3 seconds ago), and this average value is taken as the current water level. If this current water level has risen by a predetermined value (for example, 30mm) or more compared to the water level a predetermined time ago (for example, 30 seconds ago), it is determined that the person has entered the bath, and if it has fallen by a predetermined value or more compared to the water level a predetermined time ago, it is determined that the person has exited the bath. Then, in the bathing flag information of the storage unit in the control unit 30, if it is determined that the person has entered the bath, the bathing flag is stored with the bathing flag ON, and if it is determined that the person has exited the bath, the bathing flag is stored with the bathing flag OFF. In the flowchart in Figure 2, the drain discharge operation is performed while bathing. Therefore, in step S2, the bathing flag information in the memory unit is stored in the state of the bathing flag being ON, and it is recognized that the person is currently bathing.

[0032] Next, the process moves to step S3, where it is determined whether the high-level electrode 17a of the drain water level detector 17 in the drain tank 13 has been turned ON. Step S3 is a step to determine whether the drain stored in the drain tank 13 has become full. If the high-level electrode 17a is not ON, the process returns to step S1. If the high-level electrode 17a is ON, it is determined that the drain in the drain tank 13 has become full, and the process is instructed to start the drain discharge operation, and the process proceeds to step S4.

[0033] In step S4, the first water level (L1) is calculated and stored as the water level of the bathtub 40 before the drain discharge operation. The first water level (L1) here is the average value of the detection results of the water level sensor 23, which are calculated in the same manner as the current water level calculation method in step S1. The first water level (L1) at this time is the water level from the time the high water level electrode 17a is turned ON (the time when "Yes" is determined in step S3) until the switching valve 51 and the drain discharge switching valve 52 are switched from the circulation position to the drain discharge position (step S5). Note that when calculating the first water level (L1), the detection results of the water level sensor 23 before the high water level electrode 17a is turned ON may be included in the calculation of the average value of the detection results of the water level sensor 23.

[0034] In the following step S5, in order to connect the drain discharge path, the switching valve 51 and the drain drain switching valve 52 are switched to a drain discharge position in which the bath circulation circuit 2 is not connected to the bathtub 40 but is connected to the drain discharge circuit 3, and the pump 22 is activated in step S6. This starts the drain discharge operation in which the drain from the drain tank 13 is discharged into the bathroom 4. Due to the operation of the pump 22, the drain in the drain tank 13 flows through the drain discharge circuit 3 and is discharged into the bathroom 4. That is, the drain in the drain tank 13 flows out from the drain outlet pipe 15, passes through the switching valve 51 and flows into the heat exchanger side return pipe 18a, flows from the heat exchanger side return pipe 18a to the heat exchanger side out pipe 19a, passes through the drain drain switching valve 52 and flows through the drain drain pipe 20 and is discharged into the drain outlet 43 of the bathroom 4 (outside the water heater 1).

[0035] In the following step S7, it is determined whether the high-level electrode 17a of the drain water level detector 17 has turned OFF or not. If the high-level electrode 17a is not OFF, proceed to step S8; if the high-level electrode 17a is OFF, proceed to step S10.

[0036] In step S8, it is determined whether a predetermined time (for example, 90 seconds) has elapsed since the high water level electrode 17a was turned ON. If the predetermined time has not elapsed, the process returns to step S7. If the predetermined time has elapsed, the drain discharge operation is stopped in step S9 due to a potential malfunction.

[0037] In step S10, it is determined whether the low-level electrode 17b of the drain water level detector 17 has turned OFF. If the low-level electrode 17b is not OFF, the process proceeds to step S11. If the low-level electrode 17b is OFF, it is determined that the drain in the drain tank 13 has been discharged, and the process proceeds to step S13.

[0038] In step S11, it is determined whether a predetermined time (for example, 20 minutes) has elapsed since the high-water-level electrode 17a was turned OFF. If the predetermined time has not elapsed, the process returns to step S10. If the predetermined time has elapsed, the drain discharge operation is stopped in step S12 due to a potential malfunction. Note that the drain discharge operation may also involve a control operation that does not perform the process in step S11.

[0039] In step S13, the pump 22 is stopped. This stops the discharge of drain from the drain tank 13.

[0040] In the following step S14, the drain drain position of the switching valve 51 and the drain drain switching valve 52 is maintained in order to connect the pipe cleaning path so that the piping of the drain discharge circuit 3 through which the drain has flowed can be cleaned, and the hot water filling solenoid valve 26 is opened in step S15. When the hot water filling solenoid valve 26 is opened, clean hot water or water flows from the hot water filling pipe 25 into the drain discharge circuit 3 and the piping is cleaned.

[0041] In the following step S16, it is determined whether the cumulative amount of hot and cold water supplied from the hot water filling pipe 25 to the drain discharge circuit 3 has reached a predetermined amount (for example, 4L). The cumulative amount of hot and cold water supplied is detected by a hot water volume sensor 28 installed in the hot water filling pipe 25. If the cumulative amount of hot and cold water supplied has not reached a predetermined amount, the process proceeds to step S17; if the cumulative amount of hot and cold water supplied has reached a predetermined amount, the process proceeds to step S19.

[0042] In step S17, it is determined whether a predetermined time (for example, 38 minutes) has elapsed since the hot water filling solenoid valve 26 was opened. If the predetermined time has not elapsed, the process returns to step S16. If the predetermined time has elapsed, the process is considered to have malfunctioned, and the pipe cleaning operation is stopped in step S18 due to an error.

[0043] In step S19, the hot water solenoid valve 26 is closed. This stops the pipe cleaning operation.

[0044] In the following step S20, in order to connect the bath circulation path, the switching valve 51 and the drain drain switching valve 52 are switched to the circulation position in which the bath circulation circuit 2 is in communication with the bathtub 40, and the pump 22 is operated for a predetermined time (for example, 60 seconds) in step S21. As a result, the hot water from the bathtub 40 is supplied to the bath circulation circuit 2 and circulated, so even if air has entered the bath circulation circuit 2 due to the operation of the switching valve 51 and the drain drain switching valve 52, the bath circulation circuit 2 can be filled with the hot water from the bathtub 40.

[0045] In the following step S22, the pump 22 is stopped to complete the drain discharge operation. After a predetermined waiting time (for example, 35 seconds) has elapsed since the pump 22 stopped, in step S23, the second water level (L2) is calculated as the water level after the drain discharge operation is completed. The second water level (L2) here is the average value of the detection results of the water level sensor 23, which are calculated in the same manner as the current water level calculation method in step S1. The second water level (L2) at this time is calculated based on the detection results detected by the water level sensor 23 after the waiting time in step S22 has elapsed. That is, in calculating the second water level (L2), the detection results of the water level sensor 23 before the waiting time in step S22 have elapsed are not included in the calculation of the average value of the detection results of the water level sensor 23.

[0046] In the following step S24, the first water level (L1) stored in step S4 is read, and this first water level (L1) is compared with the second water level (L2) obtained in step S23 to determine whether the condition "second water level (L2) > first water level (L1) - h" is met. In other words, it is determined whether the person bathing got out of the bathtub 40 during the drain discharge operation. The h corresponds to the amount of water level change (for example, 30 mm) that occurs when a person gets out of the bathtub 40, and an arbitrary value is set according to the shape of the bathtub 40, etc. Note that the example of 30 mm may be used as a fixed value for the water level change h, but it may also be changed manually or automatically according to the shape of the bathtub 40, etc.

[0047] In the flowchart of Figure 2, the drain discharge operation during bathing is shown, so the first water level (L1) is the water level of the bathtub 40 when a person is bathing, and "first water level (L1)-h" is the water level of the bathtub 40 assuming the person has left the bath. Therefore, if "second water level (L2) > first water level (L1)-h" is true, it is determined that the person has not left the bath (is still bathing) during the drain discharge operation, and the process returns to step S1. In this case, the bathing flag stored in the memory unit remains in the ON state. On the other hand, if "second water level (L2) > first water level (L1)-h" is not true, it is determined that the person has left the bathtub 40 during the drain discharge operation, and the bathing flag stored in the memory unit in step S25 is turned OFF, and the process returns to step S1. This determination in step S24 makes it possible to detect whether the person who was bathing during the drain discharge operation continued to bathe or left the bath.

[0048] Next, we will explain the case where the drain operation is performed before bathing. The flowchart in Figure 3 shows the process when the drain discharge operation is performed before bathing. As shown in Figure 3, in step S31, the water level detection result of the bathtub 40 is obtained and the current water level is calculated. Step S31 is almost the same as step S1 in Figure 2, so the explanation is omitted. In the flowchart in Figure 3, the drain discharge operation is performed before bathing (while getting out of the bath), so in step S32, the bathing flag information in the memory unit is stored in the state of bathing flag OFF, and it is recognized that the person is not currently bathing (getting out of the bath). Steps S33 to S53 are almost the same as steps S3 to S23 in Figure 2, so the explanation is omitted.

[0049] In step S54, the first water level (L1) stored in step S34 is read, and this first water level (L1) is compared with the second water level (L2) obtained in step S53 to determine whether the condition "second water level (L2) < first water level (L1) + h" holds true. In other words, it is determined whether a person who was not bathing entered the bathtub 40 while the drain discharge operation was in progress. The h corresponds to the amount of water level change (for example, 30 mm) that occurs when a person immerses themselves in the bathtub 40, and an arbitrary value is set according to the shape of the bathtub 40, etc. Note that the example of 30 mm may be used as a fixed value for the water level change h, but it may also be changed manually or automatically according to the shape of the bathtub 40, etc.

[0050] In the flowchart of Figure 3, the drain discharge operation before bathing is shown, so the first water level (L1) is the water level of the bathtub 40 when no one is bathing, and "first water level (L1) + h" is the water level of the bathtub 40 assuming a person is bathing. Therefore, if "second water level (L2) < first water level (L1) + h" is true, it is determined that the person is not bathing (is getting out of the bath) during the drain discharge operation, and the process returns to step S31. In this case, the bathing flag stored in the memory unit remains in the OFF state. On the other hand, if "second water level (L2) < first water level (L1) + h" is not true, it is determined that the person entered the bathtub 40 during the drain discharge operation, and the bathing flag stored in the memory unit in step S55 is turned ON, and the process returns to step S31. This determination in step S54 makes it possible to detect whether the person who was not bathing entered the bathtub 40 during the drain discharge operation.

[0051] As described above, according to the water heater 1 of this embodiment, the first water level (L1) before the drain discharge operation is performed is calculated and stored in the detection result of the water level sensor 23, and this stored first water level (L1) is compared with the second water level (L2) calculated after the completion of the drain discharge operation to determine whether a person is entering or leaving the bathtub 40 during the drain discharge operation. In this way, by storing the first water level (L1) before the drain discharge operation is performed, the switching valve 51 and the drain drain switching valve 52 can be used to switch the bath circulation circuit 2 from a circulation position that communicates with the bathtub 40 to a drain discharge position that does not communicate with the bathtub 40, and then compare it with the second water level (L2) when the bath circulation circuit 2 is switched back to a circulation position that communicates with the bathtub 40.Therefore, it is possible to suitably detect whether a person is entering or leaving the bathtub 40 during the drain discharge operation, when the bath circulation circuit 2 is in a drain discharge position that is not communicating with the bathtub 40 but is communicating with the drain discharge circuit 3.

[0052] Furthermore, the first water level (L1) before the drain discharge operation is the water level from the instruction to start the drain discharge operation until the switching valve 51 and the drain drain switching valve 52 are switched from the circulation position to the drain discharge position. As a result, the water level just before the bath circulation circuit 2 and the bathtub 40 are disconnected can be obtained as the first water level (L1) before the drain discharge operation, making it possible to determine with higher accuracy whether a person is entering or leaving the bathtub 40 during the drain discharge operation.

[0053] Furthermore, the second water level (L2) after the drain discharge operation is completed is the water level when the switching valve 51 and the drain drain switching valve 52 are switched from the drain discharge position to the circulation position, the pump 22 is operated for a predetermined time, and a predetermined waiting time has elapsed after the pump 22 stops operating. As a result, even after the drain discharge operation is performed, the bath circulation circuit 2 is filled with bath water from the bathtub 40 and does not contain air or anything else, and the water level in the bathtub 40 has stabilized. This allows for more accurate determination of whether a person is entering or leaving the bathtub 40 during the drain discharge operation.

[0054] As described above, the water heater 1 of this embodiment can discharge the condensate generated in the latent heat exchanger 10 into the bathroom 4, and can suitably detect when a person enters or leaves the bathtub 40 during this drain discharge operation. Therefore, even if the drain discharge operation is performed when a person is in the bathroom 4, the timer of the control unit 30 can accurately measure the time the person is bathing in the bathtub 40. As a result, by notifying the bather through the bathroom remote control 31 or kitchen remote control 32 in the event of prolonged bathing, the bather can be alerted, and a person outside the bathroom 4 can understand the bathing situation of the person inside the bathroom 4 and prevent bathing accidents.

[0055] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the technical concept of the present invention. For example, the drain pipe 20 may be directed to a drain outside the water heater 1 other than the bathroom 4. [Explanation of Symbols]

[0056] 1. Water heater 2 Bath circulation circuit 3. Drain discharge circuit 4 Bathroom 7. Hot water heat exchanger 8. Bath heat exchanger 9. Sensible heat exchanger 10 Latent heat exchanger 11 Drain collection pan 12 Neutralizer 13 Drain Tank 14 Drain inlet pipe 15 Drain outlet pipe 16. Check valve 17. Drain water level detector 17a High water level electrode 17b Low water level electrode 18 Bath circulation return pipe 18a Heat exchanger side return piping 18b Return piping on the bathtub side 19 Bath circulation supply pipe 19a Heat exchanger side supply piping 19b Piping supplying to the bathtub 20 Drain pipe 21 Bath return temperature sensor 22 pumps 23 Water level sensor 24 Bath water flow switch 25. Hot water supply pipe 26. Solenoid valve for filling with hot water 27a, 27b Check valve 28. Water volume sensor 29 Bath temperature sensor 30 Control Unit 31 Bathroom remote control 32 Kitchen Remote Control 40 Bathtubs 41 Circulation Adapter 42 Waterproof tray 43 Drain 51 Switching valve 52 Drain drain switching valve

Claims

1. A water heater comprising a bath circulation circuit that circulates bath water using a pump, a drain discharge circuit that discharges drain from a latent heat exchanger to the outside through a part of the bath circulation circuit, and a switching means that switches between a circulation position in which the bath circulation circuit is connected to the bathtub, and a drain discharge position in which the bath circulation circuit is not connected to the bathtub and is connected to the drain discharge circuit, wherein the water heater performs a drain discharge operation to discharge drain to the outside using the drain discharge circuit, The bath circulation circuit includes a water level sensor that detects the water level in the bathtub, and a control unit that determines whether a person enters or exits the bathtub based on the detection result of the water level sensor. The control unit, based on the detection result of the water level sensor, stores the water level before the drain discharge operation, compares this stored water level with the water level after the drain discharge operation is completed, and determines whether a person is entering or leaving the bathtub during the drain discharge operation.

2. In the water heater according to claim 1, The water level before the drain discharge operation is the water level from the time the instruction to start the drain discharge operation is given until the switching means is switched from the circulation position to the drain discharge position, in a water heater.

3. In the water heater according to claim 1 or 2, The water level after the completion of the drain discharge operation is the water level when the switching means is switched from the drain discharge position to the circulation position, the pump is operated for a predetermined time, and a predetermined waiting time has elapsed after the pump has stopped operating.

4. In the water heater according to claim 1, A drain tank that neutralizes and temporarily stores the condensate generated in the latent heat exchanger, It is equipped with a drain water level detector installed in the drain tank to detect the water level of the stored drain, The control unit, When the drain water level in the drain tank rises, the system instructs the start of the drain discharge operation, and the water level in the bathtub at this time is stored as the water level before the drain discharge operation. Switch the switching mechanism from the circulation position to the drain discharge position, and activate the pump. When the drain water level in the drain tank drops low, the pump stops operating. After passing a predetermined amount of clean hot water or water through the drain discharge circuit, A water heater comprising a configuration that switches a switching mechanism from a drain discharge position to a circulation position, and sets the water level in the bathtub after a predetermined waiting period has elapsed following the operation of the pump for a predetermined time to the water level after the drain discharge operation is completed.

Images