JPS6251366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a circulating hot water supply device that immediately supplies hot water when a hot water tap is opened.

BACKGROUND ART A conventional circulating hot water supply system of this type was constructed as shown in FIG. That is, a hot water feed pipe 2 and a hot water return pipe 3 are connected to the boiler 1, and the hot water feed pipe 2 is provided with hot water taps 4 and 5. A circulation pump 6 is inserted into the hot water return pipe 3 to circulate hot water from the boiler 1 to the hot water feed pipe 2 and the hot water return pipe 34. This circulation pump 6
is provided for the purpose of supplementing heat radiation from the hot water sending pipe 2 and the hot water return pipe 3, and is therefore attached to the hot water return pipe 3 so as not to create resistance during hot water supply.
7 is a cistern, which is installed at a higher position than the hot water taps 4 and 5.

Normally, a small amount of hot water is circulated by the circulation pump 6, but when the hot water tap 4 or 5 is opened, hot water is supplied from the hot water tap 4 or 5 by the water head pressure of the cistern 7. Regarding control, since the circulation hot water system was originally intended for large-scale equipment, no particular consideration was given to it, and the circulation pump 6 was turned on and off by a manual switch 8, and hot water was normally constantly circulated.

Problems to be Solved by the Invention Since this conventional circulating hot water supply device is configured as described above, it has the following drawbacks.

(1) Hot water is supplied to the hot water faucet only through the hot water feed pipe, so the hot water feed pipe must be thick enough to accommodate the amount of hot water being supplied, and the hot water return pipe is usually of the same diameter as the hot water feed pipe. Because it was used as
It required a lot of piping space and was expensive.

(2) Because the diameter of the piping is large, the area in contact with the surrounding air is also large, which increases the amount of heat dissipated during hot water circulation. In particular, hot water is constantly circulated and preheated so that hot water can be supplied at any time, so the amount of heat released is extremely large.

The present invention solves the drawbacks of the conventional circulating hot water supply system, and aims to reduce piping space and heat radiation loss from the piping route, and performs rational control, especially when the water supply means is a hot water tap. An object of the present invention is to provide a circulating water heater that can be controlled even when the water head pressure is not high.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the circulation water heater of the present invention includes a circulation pump and a backflow prevention valve provided upstream of the connection between the hot water feed pipe and the bypass pipe, and A flow rate difference detection means and a pressure detection means are provided in the piping route, and the circulation pump is activated and the route switching valve is controlled to be switched based on the flow rate difference or pressure change in the piping route.

Function: With this configuration, hot water is supplied to the hot water faucet through both the hot water supply pipe and the return pipe during hot water supply, making it possible to reduce the diameter of the pipe and the heat radiation area. Furthermore, by providing a check valve and controlling the path switching valve and circulation pump, the water supply means can eliminate water head pressure with respect to the hot water tap.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings.

In FIG. 1, a ball tap 11 serving as a water supply means is provided inside a hot water storage type boiler 12 serving as a heat source, and supplies water by opening and closing a water pipe.

Since the water pressure in the boiler 12 is separated from the water supply by the ball tap 11, only atmospheric pressure is applied to the boiler 12. The water in the boiler 12 is heated by the heater 13 and becomes hot water. A thin hot water feed pipe 14 and a hot water return pipe 15 are connected to the boiler 12 to form a piping route. And the hot water supply pipe 14 and the hot water return pipe 15 have hot water taps 16 and 17.
is provided. The hot water in the boiler 12 has no head pressure with respect to the hot water taps 16 and 17. The hot water feed pipe 14 is provided with a circulation pump 18 for circulating hot water. Hot water feed pipe 14
and the hot water return pipe 15 are connected by a bypass pipe 20 via a route switching valve 19, and the circulation pump 18
The check valve 25 is connected to the upstream side of the connecting portion 20' of the bypass pipe 19. Circulation pump 1
A check valve 25 and a pressure detection means 26 are sequentially provided on the discharge side of the pump 8. 27 is a pressure tank. In addition, the hot water feed pipe 14 has a flow rate sensor ().
21, Hot water return pipe 15 has a flow rate sensor () 2
2 is provided, and the control device 2 controls the flow rate difference between the two.
A flow rate difference detection means is constructed by calculating within 3. The pressure detection means 26 and a thermostat 24 for detecting the temperature of the piping route are also connected to the control device 23 by wiring. Route switching valve 19
and the circulation pump 18 is connected to the flow rate sensor () 2
It is controlled by a control device 23 based on signals from a flow rate difference detection means 22, a pressure detection means 26, and a thermostat 24. Route switching valve 19
selects the piping route side when circulating hot water, and connects the hot water feed pipe 14 from the boiler 12 with the circulation pump 18.
The hot water is circulated through the hot water return pipe 15 to the boiler 12 again, and when hot water is supplied, the route switching valve 1
9 selects the bypass pipe 20 side, the hot water is controlled to be guided from the boiler 12 to the hot water tap 16 or 17 through both the hot water feed pipe 14 and the hot water return pipe 15. The circulation pump 18 is
When hot water is being circulated, it is controlled according to the thermostat 24, and when hot water is being supplied by opening the hot water tap 16 or 17, it is controlled according to the pressure detecting means 26 and the flow rate difference detecting means. Further, when the circulation pump 18 is stopped and the hot water taps 16 and 17 are closed, the route switching valve 19 selects the bypass pipe 20 side, and the hot water feed pipe before the backflow prevention valve 25 and the route switching valve 19 14 and hot water return pipe 15 maintain the cut-off pressure before the circulation pump 18 is stopped.

Next, the operation of this embodiment will be explained.

First, it is assumed that the hot water taps 16 and 17 are closed and the temperature of the piping route is low. The thermostat 24 detects the temperature and first starts the circulation pump 18. Then, after a predetermined time, the flow rate sensors ( ) 21 and ( ) 22 operate to detect the difference in flow rate between the hot water feed pipe 21 and the hot water return pipe 22 . In this case, since the hot water taps 16 and 17 are closed, there is no difference in flow rate, and the route switching valve 19 is controlled to continue selecting the piping route. At this time, the hot water in the boiler 12 flows at a small flow rate in the direction shown by the solid arrow in FIG. When the temperature of the piping route rises, thermostat 2
4 detects this and stops the circulation pump 18.

Before this stop, the path switching valve 19
The direction is switched to select the 0 side, and the circulation pump 18 is stopped with a delay. and check valve 25
As shown in FIG. 2, the cut-off pressure before the circulation pump 18 is stopped is maintained in the subsequent hot water feed pipe 14 and the hot water return pipe before the route switching valve 19, and water is prevented from dripping into the boiler 12. ing. pressure tank 2
7 as well, the cut-off pressure is maintained in the same way, and the pressure drop caused by the cooling of the hot water in the piping route is compensated for. The water head pressure is applied to the hot water taps 16 and 17 due to the maintained pressure.

Below, when the temperature of the piping route decreases, the circulation pump 18
starts, and when the temperature rises, the circulation pump 18 stops operating, which is repeated.

Next, assume that any one of the hot water taps 16 or 17 is opened while the circulation pump 18 is stopped. At this time, the route switching valve 19 selects the bypass pipe side, so the pressure in the hot water feed pipe 14, the hot water return pipe 14, and the hot water return pipe 15 decreases. The pressure detection means 26 detects this pressure drop,
The control device 23 causes the circulation pump 18 to start and the circulation switching valve 19 to continue selecting the bypass pipe 20 side.
takes control. When the circulation pump 18 starts, hot water flows through the hot water feed pipe 14 and the hot water return pipe 15, and the flow occurs in the forward direction to the flow rate sensor (21) and in the opposite direction to the flow rate sensor (22), resulting in a flow rate difference. . Then, the pump 18 continues to be activated, and the path switching valve 19 continues to maintain selection of the bypass pipe 20 side. The pressure detection means 26 detects that the circulation pump 18 is activated and the internal pressure of the piping route gradually increases.
When a predetermined pressure is reached, it is turned off, and from then on, the path switching valve 19 and the circulation pump 1 are switched off by the flow rate difference detection means.
8 is controlled. Hot water tap 16 or 1
When all 7 are closed, the flow of hot water feed pipes 14 and 15 is stopped, and there is no difference between the flow rate sensor (21) and the flow rate sensor (22), so the control device 2
According to the command 3, the circulation pump 18 stops operating.
The path switching valve 19 also continues to select the bypass pipe side.
The cut-off pressure before the circulation pump 18 is stopped is maintained in the hot water feed pipe 14 and the hot water return pipe 15.

Note that even when the circulation pump 18 is in circulation operation and the route switching valve 19 selects the piping route side, when the hot water supply tap 16 or 17 is opened, the hot water supply pipe 1
4 and hot water return pipe 15, the path switching valve 19 can be switched to select the bypass pipe 20 side to supply hot water.

Effects of the Invention As described above, the circulation water heater of the present invention is provided with a circulation pump and a check valve on the upstream side of a hot water feed pipe and a bypass pipe, and the circulation pump and the backflow prevention valve are disposed on the upstream side of a hot water feed pipe and a bypass pipe. The following effects can be obtained by starting the system or switching the route switching valve.

(1) Hot water is supplied to the hot water faucet through both the hot water supply pipe and the hot water return pipe, and during circulation, a small flow of hot water is circulated from the hot water supply pipe to the hot water return pipe. It requires only a small diameter, requires less piping space, and can be provided at low cost.

(2) Both the hot water sending pipe and the hot water return pipe can be small in diameter, reducing the area of contact with the surrounding air, which can greatly reduce the heat radiation during circulation, which was a problem in the past.

(3) Since the activation of the circulation pump and the control of the route switching valve during hot water supply are performed by pressure detection means,
Control is possible even when the water supply means does not have head pressure with respect to the hot water tap.

(4) The backflow prevention valve and route switching valve prevent water from dripping even if the hot water tap is opened when the circulation pump is stopped.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a circulating hot water supply apparatus which is an embodiment of the present invention, FIG. 2 is a block diagram of the same apparatus, and FIG. 3 is a block diagram showing a conventional circulating hot water supply apparatus. 11... Cistern (water supply means), 12... Boiler (heat source device), 14... Hot water feed pipe, 15...
...Hot water return pipe, 16, 17...Hot water tap, 18...
Circulation pump, 19... Path switching valve, 20... Bypass pipe, 20'... Connection part, 21, 22... Flow rate sensor (), () (flow rate difference detection means), 23...
...Control device, 24...Thermostat, 25...
Non-return valve, 26...pressure detection means.

Claims (1)

[Claims] 1. A water supply means, a heat source device that heats water from the water supply means, a piping route consisting of a hot water feed pipe and a return pipe connected between the heat source device and the hot water tap, and the hot water feed pipe and return pipe. a bypass pipe that communicates with the hot water return pipe, a path switching valve that selects the hot water return pipe side or the bypass pipe side, and a circulation pump and a backflow prevention valve that are provided upstream from the connection between the hot water feed pipe and the bypass pipe. and a flow rate difference detection means for detecting a flow rate difference between the hot water sending pipe and the return pipe,
A pressure detection means for detecting a pressure change in the piping route, and a control device that starts the circulation pump and switches the route switching valve based on the flow rate difference or pressure change in the piping route. Circulating water heater.