JPH08199635A - Freezing preventing device for piping in hot water supply system - Google Patents

Abstract

PURPOSE: To provide a freezing preventing device for a hot water supply piping system which does not carry out the drainage of a water passing path in the case of the stoppage of electric supply for a short time, and keeps a hot water supplier in a reusable state. CONSTITUTION: The upstream of a water supply path 16 is shut off, and an electric three-way valve 7 is provided for changing over a hot water supply system into either of a drainage mode for opening a drainage path 5 which is branched from the water supply path 16 and communicates with the air or a water passing mode which shut off the drainage path 5 and opens the upstream of the water supply path 16. A power source changing over section 3c for changing over from a commercial power source 1 to a charging section 2 at the time of the stoppage of electric supply, a drainage section 3 for the stoppage of electric supply for changing over from the water passing mode to the drainage mode and a delay timer section 3d for delaying the beginning of changeover set by the drainage section 3 for the stoppage of electric supply for a fixed time are provided in a drainage controller 3 for changingly controlling the electric three-way valve 7. In the case of the stoppage of electric supply for a short time, the drainage of a water passing path is not carried out, and a hot water supplier 18 is prepared for its reusing after dissolving the stoppage of electric supply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe antifreezing device in a hot water supply system, and more particularly to a pipe antifreezing device in a hot water supply system that automatically drains water from the pipe.

[0002]

2. Description of the Related Art In cold regions, water in a water pipe often expands due to freezing and the pipe ruptures frequently in winter. When it is extremely cold, it is feared that the hot water supply system will be damaged not only by the outdoor piping but also by the indoor piping due to freezing. Therefore, conventionally, water is drained when there is a risk of freezing, or a heater is attached to a water passage of a water heater to warm the water heater to prevent pipe rupture and equipment damage. In addition, in the hot water supply system that automatically drains water from the pipes to prevent draining, unexpected low temperatures when going out or sleeping, and freezing without the heater working during a power outage. Piping freeze protection devices are known.

For example, a pipe antifreezing device in a hot water supply system disclosed in Japanese Patent Laid-Open No. 3-241125 will be described with reference to FIG. The arrow on the water passage in the figure indicates the drainage direction. The water heater 18 has a water supply channel 16 leading to an upstream water pipe and a hot water supply curran 10 downstream.
And a hot water supply passage 17 connected to. The water supply passage 16 is provided below the hot water supply passage 17, and the water supply passage 1
A short-circuit path 9 is provided which short-circuits and connects 6 and the hot water supply path 17. The short-circuit passage 9 is provided with a check valve 8 that allows only one-way flow from the hot water supply passage 17 to the water supply passage 16. The check valve 8 opens at the time of drainage, and plays the role of draining the water in the hot water supply passage 17 through the short-circuit passage 9. Further, the uppermost part of the water passage in the water heater 18 (hereinafter, referred to as a water passage when the water supply passage 16, the hot water supply passage 17, and the short-circuit passage 9 are not distinguished from each other) is taken into the water passage through outside air at the time of drainage. An intake valve 15 is provided to prevent negative pressure in the water channel and facilitate drainage. That is, the intake valve 1
Air flows in from 5 and is drained due to the head difference.

A temperature sensor 13 for detecting the temperature of the supplied water is provided in the water supply passage 16 in the water heater 18,
Is connected to the hot water supply controller 12 that controls the operation of the.
The hot water supply controller 12 is provided with a water temperature monitoring unit 12b that monitors whether or not the water supply temperature is equal to or lower than a predetermined temperature. Also, the water temperature monitoring unit 12b is below the first predetermined temperature (about 5 ° C)
When it is determined that the heater is connected to the hot water supply controller 12, a heater (not shown) that is energized to prevent the water temperature in the water passage from decreasing is attached to the water passage. Then, if the water temperature falls below the second predetermined temperature (about 1 ° C.) at which the water temperature is likely to freeze despite being heated by the heater, the drainage command unit 12a that commands the drainage of the water passage is provided. Further, a remote controller 14 capable of commanding drainage by remote operation is connected to the hot water supply controller 12.

In the water supply passage 16 connected to the water heater 18,
An electric three-way valve 7 is provided for switching between a water flow state connected to an upstream water supply source and a drainage state connected to the drainage channel 5 open to the atmosphere (the state shown in FIG. 8 shows the drainage state). . Further, an electric motor 4 for switching and driving the electric three-way valve 7 is provided. (Hereinafter, switching to the water flow state by the electric three-way valve 7 is called a water flow mode, and switching to the drainage mode is called a drainage mode.) Switching from the drainage mode to the water flow mode is an electric three-way The ball valve provided inside the valve 7 is rotated 90 ° clockwise in the drawing.

The drainage controller 30 for controlling the electric motor 4 is electrically connected to the hot water supply controller 12 of the hot water supply device 18. The drainage controller 30 that controls the electric motor 4 includes a commercial power source 1 and a backup power source 20.
Are connected, and a power supply switching unit 30c is provided that immediately switches the power supply from the commercial power supply 1 to the backup power supply 20 at the time of a power failure and returns to the commercial power supply 1 when the power failure is resolved. In addition, a mode switching unit 30a for instructing switching between the water-flow mode and the drainage mode of the electric three-way valve 7 and a power failure drainage command unit 30b for issuing a drainage command to the mode switching unit 30a at the time of power failure are provided.

The flowchart of FIG. 7 shows the processing of the drainage controller 30 for controlling the switching of the electric switching valve 7. The drainage controller 30 includes a commercial power source 1 and a backup power source 2.
It has two power sources, 0, and when the process is started (S5
1) First, it is determined whether the commercial power supply 1 is supplied (S52). In the case of a power failure, the electric three-way valve 7 is switched to the drainage mode by the electric motor 4 (S53) to drain the water passage. Subsequently, the commercial power source 1 is waited for restoration (S54), and if the commercial power source 1 is restored, it is determined whether or not there is a drainage command from the water heater 18 (S5).
5). The drainage command from the water heater 18 is issued when the drainage operation is performed by the remote controller 14 or when the temperature sensor 13 is used.
If the temperature detected by the temperature is below a predetermined temperature, the drainage command unit 12
A drain signal is output from a to the mode switching unit 30a of the drain controller 30. The mode switching unit 30a executes the drainage mode when there is a drainage command (S56), and otherwise executes the water passage mode (S57). Then, after executing the mode, the process returns to the first step 52 and these processes are repeated.

Therefore, the water temperature is monitored, and when the water temperature is lowered, the water passage is heated by the heater, and when the water temperature is lowered and the temperature is likely to be frozen, the water passage is drained. Further, in the case of a power failure, the drainage controller 30 that controls the electric motor 4 immediately issues a drainage command to drain the water passage. That is, even if the water heater 18 side becomes uncontrollable due to a power outage, freezing damage to the water passage can be reliably avoided. When the power failure is resolved, the water supply mode is switched to prepare for reuse of the water heater 18.

[0009]

However, in such an antifreezing device for pipes in a hot water supply system, when a power failure occurs, the water passage is immediately drained, so that there is a short-term power failure unrelated to freezing. Even
There was a problem that the water heater could not be used immediately after the power was restored.
In other words, after the power failure is resolved, the flow path upstream of the water supply channel is opened to switch to the water flow mode in preparation for reuse of the water heater. Has been replaced by. That is, the air in the water passage is only compressed by the water supply pressure due to the water passage, the air is not discharged outside the water passage, and the water passage is not filled with water. Therefore, when the water heater is used, hot water cannot be discharged immediately until the hot water supply hood is opened and the air in the water passage is discharged. Moreover, the water in the waterway was wastefully discarded by drainage, which was uneconomical, even though it was not frozen due to a short power failure. The antifreezing device for piping in the hot water supply system of the present invention solves the above-mentioned problem, and does not drain the water passage in the case of a short-term power outage unrelated to freezing, and the water heater can be quickly reused after the power is restored. The purpose is to provide a protection device.

[0010]

A pipe antifreezing device in a hot water supply system according to the present invention which solves the above-mentioned problems, has a water supply passage connecting a water heater and a water supply source and a branch connection from the water supply passage to the outside air. A drainage channel that communicates, a drainage valve that opens and closes the drainage channel, an upstream valve that opens and closes the water supply channel upstream of the branch position, a drainage mode that shuts off the upstream valve and opens the drainage valve, or the drainage In a pipe antifreezing device in a hot water supply system, comprising: a drainage control means for switching the valve to a water passage mode for opening the upstream valve and opening the upstream valve, wherein the drainage control means is connected to the drainage control means during a power failure. A backup power supply that supplies power, a power failure drainage means that switches to the drainage mode when there is a power failure, and a delay in the start of switching by the power failure drainage means during a power failure for a predetermined time And gist that a water delay means.

The pipe antifreezing device in the hot water supply system according to the second aspect of the present invention includes a water supply passage connecting the water heater and the water supply source, a drainage passage branching from the water supply passage to the outside air, and the drainage. A drainage valve for opening and closing a passage, an upstream valve for opening and closing the water supply passage upstream of the branching position, a drainage mode in which the upstream valve is shut off and the drainage valve is opened, or the drainage valve is shut off and the upstream In a pipe antifreezing device in a hot water supply system comprising a drainage control means for switching to any one of water flow modes for opening a valve, the drainage control means is a backup power supply for supplying power to the drainage control means in the event of a power failure. , A temperature sensor provided in the water supply passage for detecting the water supply temperature, a water temperature monitoring means for monitoring whether or not the water supply temperature is below a predetermined temperature at which it is likely to freeze, and a water temperature monitoring means. And gist that a low temperature water discharge means for switching to the waste water mode if it is determined that the temperature less.

Further, the pipe antifreezing device in the hot water supply system of the third invention is summarized in that the drainage control means of the first and second inventions are incorporated in the water heater.

Further, in the pipe antifreezing device in the hot water supply system according to the fourth aspect of the present invention, the backup power source of the first, second and third aspects includes commercial power charging means for charging from the commercial power source and provided in case of power failure. The point is to have prepared.

[0014]

In the pipe antifreezing device in the hot water supply system according to the first aspect of the present invention having the above structure, the backup power source supplies power to the drainage control means at the time of a power failure, and the drainage delay means in the drainage control means is the drainage means at the time of power failure. Delay the start of switching to drainage mode for a predetermined time. Then, after a lapse of a predetermined time, the drainage means during a power failure switches from the water flow mode to the drainage mode. That is, at the time of power failure, drainage is performed by the power failure drainage means, but the switching from the water flow mode to the drainage mode is not performed until a predetermined time has elapsed from the start of the power failure. That is,
If the power outage is resolved within the specified time, the water flow mode remains. Therefore, since the water in the pipe is not drained immediately after the power failure, the water heater can be promptly reused in the case of a short power failure that is unrelated to the freezing of the pipe, which is convenient.
Also, in the case of a short power outage, there is no waste water drainage, which saves water.

A second invention having the above structure is, in the pipe antifreezing device in the hot water supply system according to the first invention, a backup power source supplies power to the drainage control means at the time of power failure, and the water temperature monitoring means in the drainage control means. But,
The water temperature detected by the temperature sensor is monitored to see if it is below a predetermined temperature at which it is likely to freeze, and if the water temperature monitoring means determines that it is below the predetermined temperature, the low temperature drainage means switches to drainage mode. Regardless of this, if the temperature falls below a predetermined temperature at which it is likely to freeze, the water is drained, so it is possible to reliably prevent freezing. Further, unlike the first invention, if the water temperature is high even if there is a blackout for a long time, the water in the pipe is not drained unnecessarily, and the water heater can be promptly reused after the power failure is resolved, which is convenient. Also, if the water temperature is high, there is no waste water due to drainage, so water is saved. In addition, since the temperature sensor detects the water temperature in the water supply channel outside the water heater, and the water temperature monitoring means in the drainage control means monitors the water temperature, the water temperature on the water heater side is high and the temperature outside the water heater is likely to freeze. Even if it is, it can be drained to prevent freezing.

A third aspect of the invention having the above-mentioned structure is that in the pipe antifreezing device in the hot water system according to the first and second aspects, the drainage control means is incorporated in the water heater. Therefore, it is not necessary to provide a drainage valve and an upstream valve in the middle of the piping or to route a connection signal line to the water heater, and the installation work of the entire system is facilitated. Further, since the temperature sensor and the processing / judgment circuit provided in the water heater can be used, the entire system can be manufactured at low cost.

A fourth aspect of the present invention having the above-mentioned structure is the pipe antifreezing device in the hot water supply system according to the first, second and third aspects, wherein the backup power source is equipped with commercial power charging means and is charged from the commercial power source. Prepare for a power outage. Therefore, compared to the case of using a dry battery as a backup power source, battery replacement is not necessary, and in the case of an unexpected power failure, the situation where the backup power source is not noticed after pipe freeze damage occurs .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the structure and operation of the present invention described above, preferred embodiments of the pipe antifreezing device in the hot water supply system of the present invention will be described below. FIG. 1 is a schematic diagram of a pipe antifreezing device in a hot water supply system according to a first embodiment. The difference between the first embodiment and the conventional example is that a delay timer unit 3d is added to the drainage unit 3b during a power failure in the drainage controller 3. Therefore, other configurations are the same as those of the conventional technique, and the description of the conventional technique will be omitted. The backup power supply 2 is a commercial power charging unit 2a that stores the power required during a power failure by charging from the commercial power supply 1 before a power failure.
To provide.

Next, the drainage control process executed by the drainage controller 3 of the first embodiment will be described with reference to FIG. When a power failure occurs, the hot water supply controller 12 provided in the hot water supply device 18 stops, and during combustion, the valve opening force of a solenoid valve (not shown) is lost, the gas flow path is closed, and combustion is immediately stopped. Further, when the water passage in stopped water heater 18 is warmed by a heater (not shown) because the water temperature is low, the power supply to the heater connected to hot water controller 12 is stopped due to a power failure. On the other hand, the drainage controller 3 that controls the switching of the electric three-way valve 7
The power supply to the power source is immediately switched from the commercial power source 1 to the backup power source 20 at the same time as a power failure. When the process starts in step 1 (S1), it is first determined whether or not there is a power failure (S2), and in the case of a power failure, it is determined whether or not T seconds have elapsed from the power failure (S3). And Step 4
In, when the power failure is resolved within the predetermined time T seconds, the drainage is not performed and the process proceeds to step 7. In step 4, if the power outage is not resolved even after the lapse of the predetermined time T seconds, the electric three-way valve 7 is switched to the drainage mode (S5), and the commercial power supply 1 is waited until it is restored (S6). ). If the power failure is resolved in step 6, the process proceeds to step 7.

Subsequently, in step 7, it is determined whether or not there is a drainage command from the water heater 18. The drainage command from the water heater 18 outputs a drainage signal to the mode switching unit 3a in the drainage controller 3 when the remote controller 14 performs drainage operation or when the temperature detected by the temperature sensor 13 is equal to or lower than a predetermined temperature. (Fig. 1). The mode switching unit 3a executes the drainage mode when there is a drainage command (S9), and otherwise executes the water passage mode (S8).
After executing the mode, the process returns to the first step 2 and these processes are repeated.

In the case of a short power failure within 10 minutes, if the water temperature is low, the water passage is warmed by the heater just before the power failure, and it is unlikely that the water will freeze because the water is not drained. Therefore, the predetermined time T seconds is preferably set to about 10 minutes. Therefore, when the short-time power failure within 10 minutes is resolved, the water heater is not drained, and the water heater can be promptly reused. Also, in the case of a short power outage, there is no waste water due to drainage, so water can be saved.

Next, a second embodiment will be described with reference to FIG. The main difference from the second embodiment and the conventional example is that, in addition to monitoring the water temperature with the hot water supply controller 12 in the water heater 18, the water temperature is also the same in the drainage controller 3 that controls switching of the electric three-way valve 7. Is the point to monitor. That is, in addition to the temperature sensor 13 provided in the water heater 18, a temperature sensor 6 that detects the water temperature in the vicinity of the electric three-way valve 7 is provided in the water supply passage 16 connected to the water heater 18, and the drainage controller 3 is provided with the temperature sensor 6. A water temperature monitoring unit 3e that monitors whether or not the temperature detected by the temperature sensor 6 is below a predetermined temperature is provided, and if the temperature is below the predetermined temperature, a drainage command unit 3f that commands the mode switching unit 3a to drain water is provided.

Next, the drainage control process executed by the drainage controller 3 of the second embodiment will be described with reference to FIG. When the process starts in step 21,
Drainage controller 3 for switching control of the electric three-way valve 7.
Determines whether the temperature detected by the temperature sensor 6 near the electric three-way valve 7 is lower than or equal to a predetermined temperature (S22), and if it is lower than or equal to the predetermined temperature, the drainage mode is executed (S25). On the other hand, if the temperature detected by the temperature sensor 6 is not below the predetermined temperature,
The process proceeds from step 22 to step 23. When there is no power outage, the hot water supply controller 12 of the water heater 18 is operating, and when the remote controller 14 performs drainage operation or when the temperature detected by the temperature sensor 13 provided in the water heater 18 is equal to or lower than a predetermined temperature. Then, the drain command is issued to the mode switching unit 3a (FIG. 2). Therefore, in step 23, it is determined whether or not there is a drainage command from the water heater 18, and if there is a drainage command, the drainage mode is executed (S25), and if there is no drainage command, the water flow mode is executed (S24). Then, returning to the first step 22, these processes are repeated.

Therefore, regardless of whether or not there is a power failure, the water temperature is monitored, and if the water temperature falls below a predetermined temperature at which it is likely to freeze, the water is drained, so that freezing can be reliably prevented. Also, unlike the first embodiment, if the water temperature is high even during a long power outage, the water in the pipe is not drained unnecessarily, and the water heater can be quickly reused after the power outage is resolved, which is convenient. . Also, if the water temperature is high, there is no waste water due to drainage, so water can be saved. In addition, the temperature sensor 1 is installed in the water supply passage 16 in the water heater 18.
3 is provided and the temperature sensor 6 is provided in the water supply passage 16 outside the water heater 18, even when the water temperature inside the water heater 18 is high and the temperature outside the water heater 18 is likely to freeze, Can be drained to prevent freezing.

Next, a third embodiment will be described with reference to FIG. The main difference between the third embodiment and the second embodiment is that the pipe antifreezing device in the hot water supply system is incorporated in the water heater 18 itself. That is, the water heater 18
The electric switching valve 7, the electric motor 4, the drainage controller 3, the backup power supply 2, the temperature sensor 6, the short-circuit path 9, and the check valve 8, which are provided outside, are incorporated into the water heater 18. Therefore, it is not necessary to provide the check valve 8, the short-circuit path 9 and the electric three-way valve 7 in the middle of the piping, and to route the connection signal line between the water heater 18 and the drainage controller 3, thus eliminating the need for installation of the entire system. Construction becomes easy. Also, the water heater 18
Temperature sensor 13 and hot water supply controller 1 provided in
Since the processing / determination circuit according to 2 can be shared with the drainage controller 3, the entire system can be manufactured at low cost.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it is needless to say that the present invention can be implemented in various modes without departing from the spirit of the present invention. Is. For example, in the embodiment, the check valve 8 is provided in the short-circuit passage 9 that connects the hot-water supply passage 17 and the water-supply passage 16, and drains water from the hot-water supply passage 17 through the short-circuit passage 9 during drainage, and reverses flow during water passage. It is blocking.
However, the check valve 8 may be eliminated as shown in the schematic view of the electric switching valve 7 shown in FIG. 4A and the switching diagram (B). For example, in the drainage mode, the water source side of the water supply channel 16 is closed and the drainage channel 5 and the short circuit 9 are opened to drain the water channel. In the water channel mode, the water source side of the water channel 16 is opened and the drain channel 5 and The short circuit 9 may be closed to allow water to flow. Further, the predetermined time T seconds of the delay timer unit 3d that delays the start of switching to the drainage mode is set to preferably about 10 minutes, but depending on the installation environment of the hot water supply system, the set time is shortened to prevent freezing damage. You may. For example, it may be set to about 3 minutes assuming an extremely cold environment where the outside air temperature is -30 ° C (water temperature 3 ° C). Further, the intake valve 15 is not limited to being provided in the water heater 18,
In the case where the hot water supply scallop 10 is piped at the uppermost position as shown in FIG. 4C, the intake valve 15 may be provided on the uppermost water passage of each pipe or at each hot water supply scallop 10. Further, although the short circuit 9 is provided for draining the hot water supply channel 17, the short circuit 9 and the check valve 8 may be omitted depending on how the water channel is installed. For example, as shown in FIG. 4C, the electric three-way valve 7 is provided at the lowest piping position,
The water in the entire water passage may be piped upward so that the water can be discharged from the drain portion 5 of the electric three-way valve 7, and the short circuit 9 and the check valve 8 may be eliminated.

In addition, the motorized three-way valve 7 in the second embodiment.
The position of the temperature sensor 6 provided in the vicinity may be either the water supply passage 16 upstream of the electric three-way valve 7 or the downstream.
Further, the position of the temperature sensor 6 need not be limited to the vicinity of the electric three-way valve 7, and the position where the water temperature becomes the lowest due to the water supply passage 16 being exposed to the outside may be located at another position of the water supply passage 16. For example, it may be installed at this lowest temperature position. Also,
The electric three-way valve 7 is a system in which a ball valve is rotated by the electric motor 4, but a solenoid may be used in addition to the electric motor 4 so that the valve moves forward and backward. Further, in the embodiment, a heater is used in combination, and the heater is used to prevent freezing and the drainage is surely executed to prevent freezing. However, the heater may not necessarily be used, and the number of temperature sensors and The mounting position may be changed appropriately.

[0028]

As described above in detail, according to the pipe antifreezing device in the hot water supply system of the first invention, water is not drained in the case of short-time power failure, so that water is saved and
It is easy to use because the water heater can be reused promptly after the power failure is resolved. Further, the pipe antifreezing device in the hot water supply system according to the second aspect of the present invention does not drain water if the water temperature is high even during a long power outage, so that water can be saved and the water heater can be promptly reused after the power outage is resolved. Easy to use. Further, the pipe antifreezing device in the hot water supply system according to the third aspect of the invention can be manufactured at low cost and the installation work can be facilitated. Further, the pipe antifreezing device in the hot water supply system according to the fourth aspect of the present invention eliminates the need for battery replacement of the backup power source, and does not cause interruption of the backup power source even if an unexpected power failure occurs, thereby ensuring freezing damage to the pipe. It has an excellent effect that it can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a pipe antifreezing device in a hot water supply system according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a pipe antifreezing device in a hot water supply system according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a pipe freeze prevention device in a hot water supply system according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a pipe freeze prevention device in a hot water supply system according to another embodiment of the present invention.

FIG. 5 is a flowchart according to the first embodiment of the present invention.

FIG. 6 is a flowchart according to a second embodiment of the present invention.

FIG. 7 is a flowchart according to a conventional example.

FIG. 8 is a schematic configuration diagram of a pipe freeze prevention device in a hot water supply system according to a conventional example.

[Explanation of symbols]

 1 Commercial power supply 2 Backup power supply 3 Drainage controller 4 Electric motor 5 Drainage path 7 Electric three-way valve 8 Check valve 9 Short circuit path 16 Water supply path 17 Hot water supply path 18 Water heater

Claims (4)

[Claims] 1. A water supply passage connecting a water heater and a water supply source, a drainage passage branching from the water supply passage to connect to the outside air, a drainage valve opening / closing the drainage passage, and a drainage upstream of the branching position. Drainage control for switching between an upstream valve that opens and closes the water supply channel, a drainage mode that shuts off the upstream valve and opens the drainage valve, or a waterflow mode that shuts off the drainage valve and opens the upstream valve. In the pipe antifreezing device in the hot water supply system including means, the drainage control means, a backup power supply for supplying power to the drainage control means in the event of a power failure, and a power failure drainage means for switching to the drainage mode at the time of power failure, A pipe antifreezing device in a hot water supply system, comprising: drainage delay means for delaying the start of switching by the drainage means at the time of power failure for a predetermined time during a power failure. 2. A water supply passage connecting a water heater and a water supply source, a drainage passage branching from the water supply passage to connect to the outside air, a drainage valve opening / closing the drainage passage, and a drainage upstream of the branching position. Drainage control for switching between an upstream valve that opens and closes the water supply channel, a drainage mode that shuts off the upstream valve and opens the drainage valve, or a waterflow mode that shuts off the drainage valve and opens the upstream valve. In the pipe antifreezing device in the hot water supply system including means, the drainage control means includes a backup power supply that supplies power to the drainage control means at the time of a power failure, and a temperature sensor that is provided in the water supply passage and detects the water supply temperature. , A water temperature monitoring means for monitoring whether or not the supply water temperature is below a predetermined temperature at which freezing is likely to occur, and a low temperature for switching to the drainage mode when the water temperature monitoring means determines below a predetermined temperature. Antifreezing device of the pipe in a hot water supply system, characterized in that a time draining means. 3. A pipe antifreezing device in a hot water supply system, wherein the drainage control means according to claim 1 or 2 is incorporated in the hot water supply device. 4. The pipe antifreezing device in the hot water supply system according to claim 1, 2 or 3, wherein the backup power supply includes commercial power charging means for charging from a commercial power supply and prepared for a power failure.