Electric water heater

Abstract

To provide an electric water heater that can prevent water leakage to the outside of the unit even if the diaphragm of the pressure reducing valve deteriorates. [Solution] The present invention relates to an electric water heater (1), comprising a hot water storage tank (2), a heating device (4), a pressure reducing valve (6) that reduces the pressure of water supplied from a water source to a predetermined pressure and allows it to flow into the hot water storage tank, and a relief valve (8) that drains the expanded water from the hot water storage tank when the pressure inside the hot water storage tank exceeds a predetermined pressure. The pressure reducing valve comprises a diaphragm (52) that receives the pressure of the water downstream of the pressure reducing valve on a pressure receiving surface (52a), a valve body (48) connected to the diaphragm and adjusting the pressure of the water flowing out of the pressure reducing valve, a biasing member (54) that applies a biasing force to the valve body, and a back pressure chamber (56) formed to surround the surface of the diaphragm opposite to the pressure receiving surface. The back pressure chamber of the pressure reducing valve is provided with a drainage channel (7a) connected to a drainage pipe (28).

Description

Technical Field

[0001] The present invention relates to an electric water heater, and more particularly to an electric water heater capable of supplying hot and cold water.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2014-178074 (Patent Document 1) describes a pre-stop type electric water heater. In this electric water heater, water is supplied from a water supply source to a hot water storage tank via a check valve and a pressure reducing valve, and the water in the hot water storage tank is heated by a heater. The hot water heated in the hot water storage tank and the water branched from the water supply source are mixed to an appropriate temperature at a faucet and discharged. Further, a relief valve is attached to the hot water storage tank, and when the pressure in the hot water storage tank increases, the expanded water is discharged from the hot water storage tank, and the discharged expanded water is discharged to a drain port.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, generally, a diaphragm that receives the pressure of the hot and cold water in the hot water storage tank is provided in the pressure reducing valve that supplies water to the hot water storage tank. This diaphragm repeatedly elastically deform in response to pressure changes in the hot water storage tank in order to operate the pressure reducing valve, and has a certain lifespan. In the electric water heater described in Patent Document 1, when the diaphragm of the pressure reducing valve is damaged due to aging or the like, there is a problem that external leakage occurs where the leaked water flows to the floor or the like.

[0005] Therefore, an object of the present invention is to provide an electric water heater capable of avoiding external leakage even when the diaphragm of the pressure reducing valve deteriorates.

Means for Solving the Problems

[0006] To solve the above-mentioned problems, the present invention provides an electric water heater capable of supplying hot water, comprising: a hot water storage tank; a heating device for heating the water stored in the hot water storage tank; a pressure reducing valve connected to the hot water storage tank, which reduces the pressure of water supplied from a water source to a predetermined pressure and allows it to flow into the hot water storage tank; and a relief valve that drains the expanded water from the hot water storage tank when the pressure inside the hot water storage tank exceeds a predetermined pressure. The pressure reducing valve comprises: a diaphragm that receives the pressure of the water downstream of the pressure reducing valve at its pressure receiving surface; a valve body connected to the diaphragm and which adjusts the pressure of the water flowing out of the pressure reducing valve; a biasing member that applies a biasing force to the valve body; and a back pressure chamber formed to surround the surface of the diaphragm opposite to the pressure receiving surface. The back pressure chamber of the pressure reducing valve is provided with a drainage channel connected to a drainage pipe.

[0007] According to the present invention configured in this manner, a drainage channel connected to a drainage pipe is provided in the back pressure chamber surrounding the side of the diaphragm of the pressure reducing valve that is opposite to the pressure-receiving surface. Therefore, even if the diaphragm deteriorates and water leakage occurs, the water that flows from the diaphragm into the back pressure chamber can be drained into the drainage pipe via the drainage channel, thus preventing water leakage outside the machine.

[0008] In the present invention, preferably, the invention further includes a drainage check valve connected to a drainage channel, and an atmospheric release valve provided in a flow path branched from the drainage channel between the drainage check valve and the back pressure chamber, wherein the atmospheric release valve is closed when water flows in from the drainage channel, and opens the drainage channel to the atmosphere when no water is flowing in from the drainage channel.

[0009] With the present invention configured in this way, since a drainage check valve is connected to the drainage channel, it is possible to reliably prevent backflow of expansion water discharged from the relief valve into the pressure reducing valve. Furthermore, during the normal operation of the pressure reducing valve's diaphragm, the back pressure chamber needs to be open to the atmosphere so that elastic deformation of the diaphragm is permitted. As described above, although a drainage check valve is connected to the drainage channel, an atmospheric release valve is connected between the drainage check valve and the back pressure chamber, so during the normal operation of the diaphragm, the back pressure chamber is open to the atmosphere and the operation of the diaphragm is not hindered. On the other hand, if the diaphragm is damaged and water leakage occurs and the leaked water flows into the atmospheric release valve, the atmospheric release valve is closed and water leakage from the atmospheric release valve is prevented. Meanwhile, water leakage from the back pressure chamber is discharged into the drainage piping through the drainage check valve connected to the drainage channel.

[0010] In the present invention, preferably, the system further includes a drain hopper connected to a drain pipe, into which the expanded water discharged from the relief valve and the water discharged from the back pressure chamber via a drain check valve flow.

[0011] With the present invention configured in this way, since the wastewater from the back pressure chamber also flows into the drain hopper into which the expansion water discharged from the relief valve flows, there is no need to provide a separate drain hopper to process the wastewater from the back pressure chamber, and wastewater can be processed with a simple configuration. [Effects of the Invention]

[0012] According to the electric water heater of the present invention, even if the diaphragm of the pressure reducing valve deteriorates, external water leakage can be avoided. [Brief explanation of the drawing]

[0013] [Figure 1] This is a block diagram showing the overall configuration of an electric water heater according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the schematic configuration of a relief valve provided in an electric water heater according to an embodiment of the present invention. [Figure 3]This is a cross-sectional view showing the schematic configuration of an atmospheric release valve provided in an electric water heater according to an embodiment of the present invention. [Figure 4] This is a cross-sectional view showing the schematic configuration of a drain hopper provided in an electric water heater according to an embodiment of the present invention. [Figure 5] This is a cross-sectional view showing the schematic configuration of a pressure reducing valve provided in an electric water heater according to an embodiment of the present invention, and it is shown in the closed state. [Figure 6] This is a cross-sectional view showing the schematic configuration of a pressure reducing valve provided in an electric water heater according to an embodiment of the present invention, and it is shown in the open state. [Modes for carrying out the invention]

[0014] Next, an electric water heater according to an embodiment of the present invention will be described with reference to the attached drawings. Figure 1 is a block diagram showing the overall configuration of an electric water heater according to an embodiment of the present invention. Figure 2 is a cross-sectional view showing the schematic configuration of a relief valve provided in an electric water heater according to an embodiment of the present invention. Figure 3 is a cross-sectional view showing the schematic configuration of an atmospheric release valve provided in an electric water heater according to an embodiment of the present invention. Figure 4 is a cross-sectional view showing the schematic configuration of a drain hopper provided in an electric water heater according to an embodiment of the present invention. Figures 5 and 6 are cross-sectional views showing the schematic configuration of a pressure reducing valve provided in an electric water heater according to an embodiment of the present invention, with Figure 5 showing the valve in a closed state and Figure 6 showing the valve in an open state.

[0015] As shown in Figure 1, the electric water heater 1 according to an embodiment of the present invention includes a hot water storage tank 2, a heater 4 which is a heating device for heating the water stored in the hot water storage tank, a pressure reducing valve 6 which reduces the pressure of water supplied from a water source to a predetermined pressure and allows it to flow in, and a relief valve 8 which drains the expanded water from the hot water storage tank 2. Furthermore, the electric water heater 1 of this embodiment is equipped with a drain check valve 10 connected to the back pressure chamber of the pressure reducing valve 6, and a float valve 12 which is an atmospheric release valve. In addition, the electric water heater 1 of this embodiment is equipped with a drain hopper 14 into which the drainage from the pressure reducing valve 6 and the drainage from the relief valve 8 flow in.

[0016] The electric water heater 1 of this embodiment is configured to heat the water supplied from the water supply and let it flow out from the hot water outlet 16. Also, a part of the water supplied from the water supply is branched and flows out from the water outlet 18. In this embodiment, the hot water outlet 16 and the water outlet 18 are connected to the hot and cold water mixing faucet 20, where the hot water from the hot water outlet 16 and the water from the water outlet 18 are mixed at a predetermined ratio and discharged. Also, by closing the valve body (not shown) of the hot and cold water mixing faucet 20, the outflow of the hot water from the hot water outlet 16 and the water from the water outlet 18 is stopped. That is, the electric water heater 1 of this embodiment is a so-called "pre-stop type" electric water heater.

[0017] The hot water storage tank 2 is a tank for storing the heated hot water, and a heater 4 is disposed inside. The water in the hot water storage tank 2 is heated to a predetermined temperature by the heater 4. Also, the tap water from the water supply 22, which is the water supply source, is configured to flow into the hot water storage tank 2 through the upstream check valve 24a, the pressure reducing valve 6, and the downstream check valve 24b. By providing these upstream check valve 24a and downstream check valve 24b, the backflow of water from the electric water heater 1 to the water supply 22 and the backflow of hot water from the hot water storage tank 2 to the upstream side are prevented.

[0018] Furthermore, a drain plug 26a is connected to the bottom of the hot water storage tank 2, and an air intake plug 26b is connected to the top. These drain plug 26a and air intake plug 26b are opened when discharging the hot water stored in the hot water storage tank 2 during maintenance or the like. That is, during maintenance or the like, by opening the drain plug 26a, the hot water in the hot water storage tank 2 is discharged, and by opening the air intake plug 26b, air is inhaled into the hot water storage tank 2.

[0019] The pressure reducing valve 6 is configured to reduce the pressure of the water supplied from the water supply pipe to a predetermined pressure and allow it to flow into the hot water storage tank 2. That is, the pressure reducing valve 6 is configured to reduce the pressure of the water flowing in from the water supply passage 6a on the upstream side to a predetermined pressure and discharge it to the water supply passage 6b on the downstream side. Further, a drain passage 7a is connected to the back pressure chamber 56 (Fig. 5) provided in the pressure reducing valve 6. When there is a problem with the pressure reducing valve 6 and water leakage occurs, this water flows into the drain passage 7a and is discharged to the drain pipe 28. The specific structure of the pressure reducing valve 6 will be described later.

[0020] In addition, a check valve 10 for drainage is connected to the drain passage 7a extending from the pressure reducing valve 6. Further, a drain hopper 14 is connected to the downstream side of the check valve 10 for drainage, and a drain pipe 28 is connected to the drain hopper 14. That is, the drain passage 7a provided in the pressure reducing valve 6 is connected to the drain pipe 28 via the check valve 10 for drainage and the drain hopper 14. By providing the check valve 10 for drainage in the drain passage 7a in this way, it is possible to prevent the expanded water drained from the relief valve 8 through the relief passage 7c from flowing into the pressure reducing valve 6, which will be described later.

[0021] Furthermore, the drain passage 7a between the pressure reducing valve 6 and the check valve 10 for drainage is branched, and a float valve 12, which is an atmosphere vent valve, is provided in the branched drain passage 7b. That is, the drain passage 7a extending from the pressure reducing valve 6 is branched into two, with the check valve 10 for drainage connected to one side and the float valve 12 connected to the other side. The structure and function of the float valve 12 will be described later.

[0022] Meanwhile, a relief valve 8 is connected to the hot water storage tank 2 via an expansion water channel 2a. When the pressure inside the hot water storage tank 2 exceeds a predetermined pressure, the expansion water is drained from the relief valve 8 through the relief channel 7c. This prevents the pressure inside the hot water storage tank 2 from rising excessively due to the expansion of the water heated inside the tank. The expansion water drained from the relief valve 8 through the relief channel 7c is then joined by the drainage channel 7d downstream of the drainage check valve 10 and flows out into the drainage hopper 14 through the drainage channel 7d. As a result, the expansion water from the relief valve 8 is also discharged into the drainage piping 28 via the drainage hopper 14. The structure and function of the relief valve 8 will be described later.

[0023] Furthermore, a thermostatic valve 30 is connected to the hot water storage tank 2 via a hot water supply channel 2b. This thermostatic valve 30 is also configured to receive tap water branched from a water supply channel 6b connected downstream of the pressure reducing valve 6. Specifically, the water supply channel 6b connected downstream of the pressure reducing valve 6 is branched into two. One water supply channel 6c is connected to the hot water storage tank 2 via a downstream check valve 24b. The other water supply channel 6d is further branched and connected to the thermostatic valve 30 via a water supply channel 6e.

[0024] The thermovalve 30 is configured to mix the hot water flowing in from the hot water storage tank 2 via the hot water supply channel 2b with the water flowing in from the cold water supply channel 6e, and to discharge the water, adjusted to a predetermined set temperature, to the hot water outlet 16 via the hot water supply channel 30a. On the other hand, the cold water supply channel 6f, which branches off from the cold water supply channel 6d, is connected to the water outlet 18, and the water discharged from the pressure reducing valve 6 flows directly into the water outlet 18.

[0025] Furthermore, the drain hopper 14 is configured to receive wastewater flowing out from the drain check valve 10 and expansion water discharged from the relief valve 8. The water that flows into the drain hopper 14 is discharged into the drain pipe 28. The configuration and function of the drain hopper 14 will be described later.

[0026] Next, the configuration of the relief valve 8 will be explained with reference to Figure 2. As shown in Figure 2, the relief valve 8 comprises a casing 32, a diaphragm valve 34 disposed within the casing, and a coil spring 36 that biases the diaphragm valve 34. The casing 32 is also provided with an outlet connection 32a connected to the relief passage 7c and an inlet connection 32b connected to the expansion water passage 2a and communicating with the hot water storage tank 2. Furthermore, a relief valve opening 32c is formed inside the casing 32, communicating with the outlet connection 32a.

[0027] The diaphragm valve 34 is a valve body positioned inside the casing 32, facing the relief valve port 32c. The coil spring 36 biases the diaphragm valve 34 toward the relief valve port 32c. As a result, when the pressure inside the hot water storage tank 2 is below a predetermined pressure, the diaphragm valve 34 seats toward the relief valve port 32c due to the biasing force of the coil spring 36, and the relief valve port 32c is closed. On the other hand, when the pressure inside the hot water storage tank 2 exceeds the predetermined pressure, the force based on the pressure acting on the diaphragm valve 34 overcomes the biasing force of the coil spring 36, and the diaphragm valve 34 moves away from the relief valve port 32c.

[0028] As a result, the expanded water flowing in from the hot water storage tank 2 flows out through the relief valve port 32c into the relief channel 7c. When the pressure inside the hot water storage tank 2 decreases due to the outflow of expanded water, the diaphragm valve 34 re-seats into the relief valve port 32c. As a result, the pressure inside the hot water storage tank 2 is maintained below a predetermined pressure. In this embodiment, the diaphragm valve 34 is configured to open when the pressure inside the hot water storage tank 2 exceeds 95 kPa. Furthermore, when the pressure inside the hot water storage tank 2 exceeds a predetermined pressure, any valve of any structure can be used as a relief valve to drain expanded water from the hot water storage tank 2.

[0029] Next, the configuration of the float valve 12 will be described with reference to Figure 3. As shown in Figure 3, the float valve 12 consists of a casing 38 and a spherical valve body 40 located inside the casing 38. The lower part of the casing 38 is provided with a connection portion 38a that connects to the drainage channel 7b, and the upper surface has an opening 38b that is open to the atmosphere. Furthermore, a valve seat 38c on which the valve body 40 sits is provided on the lower edge of the opening 38b.

[0030] The valve body 40 is made of a resin sphere with a specific gravity lighter than water and is housed inside the casing 38. When no water is flowing in from the drainage channel 7b, the valve body 40 is separated from the valve seat 38c located in the opening 38b, and the drainage channel 7b is open to the atmosphere through the opening 38b. On the other hand, when water flows in from the drainage channel 7b, the valve body 40 floats on the incoming water and rises to the position shown by the dashed line in Figure 3. As a result, the valve body 40 sits on the valve seat 38c, and the opening 38b is closed. Therefore, even when water flows in from the drainage channel 7b, this water does not flow out from the opening 38b.

[0031] Thus, the float valve 12 closes when water flows in from the drainage channel 7b, and when no water is flowing in from the drainage channel 7b, it functions to open the drainage channel 7b to the atmosphere. In this embodiment, a float valve is used as the atmospheric release valve, but any valve with any structure that closes when water flows in from the drainage channel and opens the drainage channel to the atmosphere when no water is flowing in can be used as the atmospheric release valve.

[0032] Next, the configuration of the drain hopper 14 will be explained with reference to Figure 4. As shown in Figure 4, the drain hopper 14 consists of a casing 42 and a funnel section 44 located inside the casing 42. The casing 42 is an elongated cylindrical member, and the funnel section 44 is attached to it so as to narrow downwards. A connection section 42a connected to the drain channel 7d is provided at the upper end of the casing 42, and a drain pipe connection section 42b connected to the drain pipe 28 is formed on the lower side surface. Therefore, water that flows into the casing 42 of the drain hopper 14 is stored up to the height of the drain pipe connection section 42b. When the water level inside the casing 42 exceeds the height of the drain pipe connection section 42b, the water is drained through the drain pipe connection section 42b into the drain pipe 28.

[0033] On the other hand, the connection portion 42a of the casing 42 is located above the funnel portion 44, and the wastewater flowing in from the drain channel 7d through the connection portion 42a falls into the inside of the funnel portion 44. Also, the lower end of the funnel portion 44, which is positioned inside the casing 42, is located below the water level of the water stored inside the casing 42. Therefore, the funnel portion 44 functions as a trap, and the internal space of the drain pipe 28 is water-sealed against the drain channel 7d connected to the drain hopper 14. Furthermore, since the wastewater flowing from the drain channel 7d into the casing 42 falls into the funnel portion 44 from above the water level inside the casing 42, the drain channel 7d is isolated from the drain pipe 28. A check valve 45 is provided inside the drain pipe connection portion 42b, so that even if the inside of the drain channel 7d becomes negative pressure, wastewater will not flow back from the drain pipe 28. In this embodiment, a sealed drain hopper 14 is used, but an open drain hopper can also be used.

[0034] Next, the configuration of the pressure reducing valve 6 will be explained with reference to Figures 5 and 6. As shown in Figures 5 and 6, the pressure reducing valve 6 includes a casing 46, a valve body 48 disposed inside the casing 46, a valve stem 50 supporting the valve body 48, a diaphragm 52 connected to the valve stem 50, and a coil spring 54 which is a biasing member that applies a biasing force to the valve body 48.

[0035] The casing 46 is provided with an inlet connection 46a to which the upstream water supply channel 6a is connected, and an outlet connection 46b to which the downstream water supply channel 6b is connected. Inside the casing 46, there is a primary space 46d that communicates with the inlet connection 46a, and a secondary space 46e that communicates with the outlet connection 46b. These primary space 46d and secondary space 46e are connected by a valve seat 46c inside the casing 46.

[0036] Furthermore, the valve body 48 is positioned inside the casing 46 to open and close the valve seat 46c. That is, the valve body 48 is attached to the valve stem 50 and is supported so as to be slidable in a direction perpendicular to the valve seat 46c. The pressure of the water flowing out of the pressure reducing valve 6 is regulated by the valve body 48. In addition, a diaphragm 52 is attached to the valve stem 50.

[0037] Furthermore, the diaphragm 52 is a flexible, disc-shaped member and is attached to the casing 46 so as to form part of the wall surface that constitutes the secondary space 46e. That is, one side of the diaphragm 52 (the lower side in Figure 5) constitutes a pressure-receiving surface 52a, and this pressure-receiving surface 52a is subjected to the water pressure in the secondary space 46e. Therefore, the diaphragm 52 is configured to receive the water pressure downstream of the pressure reducing valve 6 at the pressure-receiving surface 52a and undergo elastic deformation.

[0038] The coil spring 54 is provided on the opposite side of the pressure-receiving surface 52a of the diaphragm 52 and is configured to apply a biasing force in the direction that opens the valve body 48 (downward in Figure 5). That is, the coil spring 54 is positioned to bias the diaphragm 52, the valve stem 50 connected thereto, and the valve body 48 downward in Figure 5. With this configuration, the valve body 48 opens and closes mainly based on the balance between the force based on the pressure acting on the pressure-receiving surface 52a of the diaphragm 52 and the biasing force of the coil spring 54. In this embodiment, the coil spring 54 is used as the biasing member, but any member that can apply a biasing force to the valve body can be used as the biasing member.

[0039] In other words, when the pressure downstream of the pressure reducing valve 6 (pressure in the secondary space 46e) is high, the force based on the pressure acting on the pressure-receiving surface 52a of the diaphragm 52 overcomes the biasing force of the coil spring 54, causing the valve body 48 to move in the closing direction (upward in Figure 5), and the pressure reducing valve 6 enters the closed state shown in Figure 5. On the other hand, when the pressure downstream of the pressure reducing valve 6 decreases, the biasing force of the coil spring 54 overcomes the force based on the pressure acting on the pressure-receiving surface 52a of the diaphragm 52, causing the valve body 48 to move in the opening direction (downward in Figure 5), and the pressure reducing valve 6 enters the open state shown in Figure 6.

[0040] Furthermore, a back pressure chamber 56 is formed on the opposite side of the pressure-receiving surface 52a of the diaphragm 52 (the upper side in Figure 5). This back pressure chamber 56 is formed to surround the side of the diaphragm 52 opposite to the pressure-receiving surface 52a (the upper side in Figure 5). The back pressure chamber 56 is also provided with a drainage channel connection part 56a for connecting the drainage channel 7a. The drainage channel 7a is connected to the drainage piping 28 via a drainage check valve 10 and a drainage hopper 14. The back pressure chamber 56 is a sealed structure, and if water flows into the back pressure chamber 56, this water will not leak out of the back pressure chamber 56 but will flow out into the drainage channel 7a through the drainage channel connection part 56a.

[0041] Next, the operation of the electric water heater 1 according to an embodiment of the present invention will be described. First, in the standby state of the electric water heater 1, a predetermined amount of hot water is stored in the hot water storage tank 2. When the temperature of the hot water in the hot water storage tank 2 drops, the heater 4 is energized to maintain the temperature of the hot water in the hot water storage tank 2 at the predetermined temperature. Also, if the pressure inside the hot water storage tank 2 exceeds a predetermined pressure due to heating the water in the hot water storage tank 2, the relief valve 8 opens. As a result, the expanded water is discharged from the hot water storage tank 2 through the expanded water passage 2a, the relief valve 8, the relief passage 7c, the drainage passage 7d, and the drainage hopper 14 to the drainage pipe 28. When the pressure inside the hot water storage tank 2 drops due to the discharge of the expanded water, the relief valve 8 closes. In addition, in the standby state, since the water pressure in the water supply passage 6b downstream of the pressure reducing valve 6 is sufficiently high, the valve body 48 of the pressure reducing valve 6 sits on the valve seat 46c, and the pressure reducing valve 6 is in the closed state shown in Figure 5.

[0042] Next, when the user operates the hot and cold water mixing faucet 20 to open the valve body (not shown) of the hot and cold water mixing faucet 20, the hot water in the hot water storage tank 2 and the water supplied from the water supply channel 6e are mixed in the thermostatic valve 30, and the hot and cold water adjusted to a predetermined temperature is supplied to the hot water outlet 16. In addition, water supplied from the water supply channel 6f is supplied to the water outlet 18. The hot and cold water supplied to the hot water outlet 16 and the water supplied to the water outlet 18 are then mixed in a predetermined ratio in the hot and cold water mixing faucet 20 and discharged.

[0043] On the other hand, when the valve body (not shown) of the hot and cold water mixing faucet 20 is opened, the pressure downstream of the pressure reducing valve 6 (the water pressure in the water supply channel 6b) decreases, causing the valve body 48 of the pressure reducing valve 6 to open. That is, when the pressure downstream of the pressure reducing valve 6 decreases, the pressure in the secondary space 46e of the pressure reducing valve 6 decreases, and the pressure acting on the pressure-receiving surface 52a of the diaphragm 52 also decreases. As a result, the biasing force of the coil spring 54 overcomes the force based on the pressure acting on the pressure-receiving surface 52a, causing the valve stem 50 and valve body 48 connected to the diaphragm 52 to move downward in Figure 5, and the valve body 48 to separate from the valve seat 46c. As a result, the pressure reducing valve 6 enters the open state shown in Figure 6.

[0044] Next, after the user operates the hot and cold water mixing faucet 20 to shut off the water, when the pressure downstream of the pressure reducing valve 6 rises above a predetermined pressure, the pressure acting on the pressure-receiving surface 52a of the diaphragm 52 also rises. As a result, the force based on the pressure acting on the pressure-receiving surface 52a overcomes the biasing force of the coil spring 54, causing the valve stem 50 and valve body 48 connected to the diaphragm 52 to move upward in Figure 6, and the valve body 48 to seat on the valve seat 46c. As a result, the pressure reducing valve 6 enters the closed state shown in Figure 5. Although the diaphragm 52 is located within the back pressure chamber 56 of the pressure reducing valve 6, which has a sealed structure, the drainage channel 7a connected to the back pressure chamber 56 is open to the atmosphere via the drainage channel 7b and the float valve 12. Therefore, the diaphragm 52 can freely elastically deform without being hindered by the back pressure chamber 56.

[0045] Thus, the pressure reducing valve 6 is opened and closed each time the user operates the hot and cold water mixing faucet 20 to stop or start the water flow, and the diaphragm 52 is elastically deformed as a result. Repeated elastic deformation can cause cracks or tears in the diaphragm 52 due to aging. If the diaphragm 52 is damaged, water in the secondary space 46e of the pressure reducing valve 6 will leak into the back pressure chamber 56 on the opposite side of the pressure-receiving surface 52a of the diaphragm 52.

[0046] Water leaking from the secondary space 46e into the back pressure chamber 56 is discharged into the drain channel 7a connected to the back pressure chamber 56, and then discharged into the drainage piping 28 via the drainage check valve 10, drain channel 7d, and drainage hopper 14. Drain channel 7b branches off from drain channel 7a, and a float valve 12 is connected to drain channel 7b. However, when wastewater flowing into drain channel 7a reaches the float valve 12 through drain channel 7b, the opening 38b of the float valve 12 is closed by the valve body 40, so wastewater does not leak from the float valve 12.

[0047] According to the electric water heater 1 of the embodiment of the present invention, a drainage channel 7a connected to a drainage pipe 28 is provided in the back pressure chamber 56 surrounding the side of the diaphragm 52 of the pressure reducing valve 6 that is opposite to the pressure receiving surface 52a. Therefore, even if the diaphragm 52 deteriorates and water leakage occurs, the leaked water that flows from the diaphragm 52 into the back pressure chamber 56 can be drained to the drainage pipe 28 via the drainage channel 7a, thereby preventing water leakage outside the unit.

[0048] Furthermore, according to the electric water heater 1 of this embodiment, since a drain check valve 10 is connected to the drain channel 7a, it is possible to prevent the expanded water drained from the relief valve 8 through the relief channel 7c from flowing into the pressure reducing valve 6. In addition, although a drain check valve 10 is connected to the drain channel 7a, a float valve 12, which is an atmospheric release valve, is connected between the drain check valve 10 and the back pressure chamber 56, so during the normal operation of the diaphragm 52, the back pressure chamber 56 is released to the atmosphere and the operation of the diaphragm 52 is not hindered. On the other hand, if the diaphragm 52 is damaged and water leakage occurs and the leaked water flows into the float valve 12, the float valve 12 is closed and water leakage from the float valve 12 is prevented. Meanwhile, water leakage from the back pressure chamber 56 is discharged into the drain piping 28 through the drain check valve 10 connected to the drain channel 7a.

[0049] Furthermore, according to the electric water heater 1 of this embodiment, since the wastewater from the back pressure chamber 56 also flows into the drain hopper 14 into which the expansion water discharged from the relief valve 8 flows, there is no need to provide a separate drain hopper 14 to process the wastewater from the back pressure chamber 56, and wastewater can be processed with a simple configuration.

[0050] Although embodiments of the present invention have been described above, various modifications can be made to the embodiments described above. [Explanation of symbols]

[0051] 1. Electric water heater 2. Hot water storage tank 2a Expansion water channel 2b Hot water supply flow path 4. Heater (heating device) 6 Pressure Reducing Valve 6a Water supply channel 6b Water supply channel 6b Water supply channel 6c Water supply channel 6d Water supply channel 6e Water supply channel 6f Water supply channel 7a Drainage 7b Drainage channel 7c Relief channel 7d drainage canal 8. Relief valve 10 Drain check valve 12. Float valve (atmospheric release valve) 14. Drain hopper 16 Hot water outlet 18 Water outlet 20 Hot water mixing faucet 22. Water supply 24a Upstream check valve 24b Downstream check valve 26a Drain plug 26b Intake valve 28 Drainage piping 30 Thermovalve 30a Hot water supply flow path 32 Casing 32a Outlet connection section 32b Inflow connection section 32c relief valve opening 34 Diaphragm valve 36 Coil springs 38 Casing 38a Connection part 38b opening 38c valve seat 40 valve body 42 Casing 42a Connection part 42b Drainage pipe connection 44 Funnel part 45 Check valve 46 Casing 46a Inlet connection 46b Outlet connection 46c valve seat 46d Primary space 46e Secondary space 48 Valve body 50 valve stems 52 Diaphragm 52a Pressure-receiving surface 54. Coil spring (biasing member) 56 Back pressure chamber

Claims

1. An electric water heater capable of supplying hot and cold water, Hot water storage tank and A heating device that heats the water stored in this hot water storage tank, A pressure reducing valve connected to the hot water storage tank reduces the pressure of water supplied from the water source to a predetermined pressure and allows it to flow into the hot water storage tank. The system includes a relief valve that drains expansion water from the hot water storage tank when the pressure inside the hot water storage tank exceeds a predetermined pressure, The above pressure reducing valve is, The water pressure downstream of the above-mentioned pressure reducing valve is received by a diaphragm that receives the pressure on its pressure-receiving surface, A valve body connected to this diaphragm adjusts the pressure of the water flowing out of the pressure reducing valve, A biasing member that applies a biasing force to the valve body, The diaphragm comprises a back pressure chamber formed to surround the surface of the diaphragm opposite to the pressure-receiving surface, An electric water heater characterized in that the back pressure chamber of the pressure reducing valve described above is provided with a drainage channel connected to a drainage pipe.

2. Furthermore, a drainage check valve connected to the drainage channel, This includes an atmospheric release valve provided in a flow path branched from the drainage channel between this drainage check valve and the back pressure chamber, The electric water heater according to claim 1, wherein the above-mentioned atmospheric release valve is closed when water flows in from the above-mentioned drainage channel, and when no water is flowing in from the above-mentioned drainage channel, the above-mentioned drainage channel is opened to the atmosphere.

3. Furthermore, the electric water heater according to claim 2, which has a drain hopper connected to a drain pipe, and is configured such that the expansion water discharged from the relief valve and the water discharged from the back pressure chamber via the drain check valve flow into the drain hopper.

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