JPH0332933Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention supplies water supplied to a hot water storage tank to a heating device installed outside the hot water storage tank, and returns the hot water heated here to the hot water storage tank. The present invention relates to a water heater that stores hot water in a temperature stratified state and uses it for hot water supply.

(b) Conventional technology Conventionally, this type of water heater has been designed to drain water from the circulation circuit through an anti-freeze drain valve when the water in the circulation circuit is in danger of freezing (see Japanese Utility Model Application Publication No. 58-49151). In order to prevent freezing, the piping of the circulation circuit was heated with a heater.

However, because the location in the circulation circuit that cools quickly varies depending on usage conditions (for example, the amount of hot water remaining in the hot water storage tank), the freezing danger temperature has to be set relatively high. For this reason, the former method has the drawback that water in the circulation circuit is frequently discharged, resulting in wasted water resources, while the latter method increases power consumption, posing a problem in terms of energy conservation.

In addition, as disclosed in Japanese Utility Model Application Publication No. 57-182071, a plurality of antifreeze thermostats are provided in the circulation circuit, and the circulation pump is operated by the output of one of these antifreeze thermostats to prevent freezing. There are also suggestions for what to do.

However, since the locations in the circulation circuit that are susceptible to freezing differ depending on whether or not there is hot water remaining in the hot water storage tank, accurate antifreeze operation could not be expected even with this system.

(c) Problems to be solved by the invention This invention detects the temperature of the part of the circulation circuit that is most likely to freeze, regardless of whether there is hot water left in the hot water storage tank, and ensures that antifreeze operation is performed accurately. The purpose is to

(d) Means for solving the problem This invention has a hot water storage tank with a water supply pipe connected to the lower part and a hot water supply pipe to the upper part, a heating device installed outside the tank, and a circulation pump, A hot water supply device comprising a circulation circuit that supplies water from the hot water storage tank to the heating device from a water outlet at the bottom of the hot water storage tank, and returns hot water heated by the heating device to the hot water storage tank from a hot water return port at the top of the hot water storage tank, a first antifreeze thermometer installed in a circulation circuit near the water outlet at the bottom of the hot water storage tank;
a second anti-freezing thermometer provided near the heating device and in the circulation circuit on the inflow side of the heating device;
The configuration includes an antifreeze device that operates a circulation pump using the output of one of these antifreeze thermostats.

(E) Effect Among the multiple anti-freeze thermoses, when there is hot water left in the hot water storage tank, there is heat conduction from the hot water storage tank. The second antifreeze thermometer senses the freezing danger temperature first. On the other hand, when there is no hot water left in the hot water storage tank, the first antifreeze thermometer installed in the circulation circuit near the water outlet at the bottom of the hot water storage tank detects the freezing danger temperature first. In this way, when any of them detects a freezing dangerous temperature, the circulation pump is operated and the water or hot water in the hot water storage tank is circulated and supplied to the circulation circuit. As a result, when all the antifreeze thermometers detect a temperature higher than the freezing danger temperature, the circulation pump stops and the antifreeze operation ends. In this way, regardless of whether or not there is hot water left in the hot water storage tank, the temperature of the parts of the circulation circuit that are at risk of freezing due to a drop in ambient temperature can be accurately detected by multiple freeze prevention thermos, and the freezing danger temperature can be set to a low value. Therefore, there is no need to perform antifreeze operations frequently. Moreover, since the system supplies water or hot water from a hot water storage tank to the circulation circuit to prevent freezing, there is no need to worry about wasting water or increasing electricity consumption as in the past.

(f) Examples Hereinafter, examples of this invention shown in the drawings will be described.

FIG. 1 shows an example of a water heater to which this invention is applied. In Figure 1, 1 is a hot water storage tank with a water supply pipe 2 connected to the bottom and a hot water supply pipe 3 connected to the top, and 4 is a circulation circuit connecting a water outlet 5 at the bottom of the hot water storage tank and a hot water return port 6 at the top of the hot water storage tank. The circulation circuit 4 is equipped with a circulation pump 7, a check valve 8, a flow switch 9, and a heating device 10 in this order.
11 is a burner serving as a heat source for the heating device 10; 12 is a fuel supply pipe to the burner 11; 13 is a fuel supply pipe 1
2 is a fuel valve installed, 14 is an exhaust fan, 15
1 is an exhaust pipe, 16 is a gas-liquid separation section installed in the circulation circuit 4 on the outlet side of the heating device 10, and 17 is a gas-liquid separation section 1.
6 and an air vent pipe connecting the hot water supply pipe 3, 18 a temperature sensor for detecting the hot water temperature To at the outlet of the heating device 10, 19 a temperature sensor for detecting the water temperature at the lower part of the hot water storage tank 1, 20 an operation switch, 21 22 is a temperature setting device, 22 is an anti-freeze thermometer attached to the circulation circuit 4 immediately downstream of the circulation pump 7, 23 is an anti-freeze thermometer attached to the circulation circuit 4 near the inlet of the heating device 10, and 24 is a circulation Pump 7, burner 1
This is a control device that also serves as an antifreeze device that controls the exhaust fan 1 and the exhaust fan 14. The circulation circuit 4 is wrapped with heat insulating material except for the parts where the heating device 10 and the antifreeze thermostats 22 and 23 are attached, so that the antifreeze thermostats 22 and 23 can quickly respond to changes in the ambient temperature. .

FIG. 2 shows a specific circuit example of the control device 24. As shown in FIG. In FIG. 2, 25 and 26 are bus bars connected to the power supply, 27 is an operation switch 20, and a temperature setting device that operates when either the operation switch 20 or the antifreeze thermometer 22 or 23 is on, and the temperature Ti detected by the temperature sensor 19 and the temperature setting device Compare the desired set temperature Ts according to 21 and find that Ti is
Output switches 271, 272 when lower than Ts
The hot water thermometer 28 turns on the timer switch 281 when either the output switch 271 or the antifreeze thermometer 22 or 23 is on.
Output switch 271, antifreeze thermos 22, 23
A delay off timer device 29 turns off the timer switch 281 after a set time (45 seconds as an example) after all of the temperature sensor 18 is turned off.
30 is a pump control device that compares the detected temperature To with the set temperature of the temperature setting device 21 and operates the circulation pump 7 while adjusting the pump flow rate in a direction in which To approaches Ts; The timer switch 301 is activated after a set time (10 seconds as an example) from the time when the power is applied through the
31 is a relay for driving the exhaust fan 14 connected in parallel to the delay-on timer device 30; 32 is a flow switch 9, an output switch 272 and a timer switch 3;
This burner control device opens the fuel valve 13 and operates the burner 11 when energized through the burner 01. Note that the anti-freezing thermometers 22 and 23 are turned on when the detected temperature is below the freezing danger temperature (for example, 2° C.), and turned off when the detected temperature is 6° C. or higher.

When the operation switch 20 is turned on, the hot water thermometer 27 compares the temperature Ti detected by the temperature sensor 19 and the set temperature Ts of the temperature setting device 21. At this time, if Ti is lower than Ts, the output switches 271 and 272 are turned on. Additionally, when output switch 271 is turned on, delay off timer device 28 turns on timer switch 281. Therefore, the pump control device 29 operates the circulation pump 7 and also controls the temperature detected by the temperature sensor 18.
Compare To with the set temperature Ts, and adjust the pump flow rate so that To approaches Ts.

When the circulation pump 7 operates, the flow switch 9
detects running water in the circulation circuit 4 and turns on. Also, since output switch 272 is already on, delay-on timer device 30 and relay 3
1 is energized. At this time, the exhaust fan 14 is operated and so-called pre-purge is started. after that,
Setting time of delay-on timer device 30 (10 seconds)
lapses and the timer switch 301 is turned on, the burner control device 32 opens the fuel valve 13 and causes the burner 11 to perform combustion.

When the burner 11 starts combustion, water entering the circulation circuit 4 from the water outlet 5 of the hot water storage tank 1 is transferred to the heating device 10.
The water receives combustion heat from the burner 11 and becomes hot water while passing through the heating device 10. The hot water from the heating device 10 passes through the circulation circuit 4 and enters the hot water storage tank 1 from the hot water return port 6. Furthermore, the pump control device 29 compares the temperature To detected by the temperature sensor 18 with the set temperature Ts, and adjusts the pump flow rate so that To approaches Ts. When the flow rate is small and the water temperature on the inlet side of the heating device 10 is high, the pump flow rate becomes large. Therefore, hot water maintained at approximately the set temperature is stored in the hot water tank 1 in order from the top.

As a result, when the temperature Ti detected by the temperature sensor 19 becomes equal to or higher than the set temperature Ts, the hot water thermometer 27 turns off the output switches 271 and 272. At this time, the burner control device 32 is de-energized and the burner 11 stops combustion. Further, the delay off timer device 28 turns off the timer switch 281 when 45 seconds have elapsed since the burner 11 stopped.
The pump control device 29 is de-energized. Therefore, the operation of the circulation pump 7 is continued for 45 seconds after the burner 11 is stopped, and boiling can be prevented from occurring in the heating device 10 due to after-boiling. In addition, the set time (45 seconds) of the delay off timer device 28 is the time required for the water at the water outlet 5 to reach the hot water return port 6 via the circulation circuit 4 when the circulation pump 7 is operated at the minimum flow rate. Since this is set, all of the hot water in the circulation circuit 4 can be collected into the hot water storage tank 1.

In this way, the hot water stored in the hot water storage tank 1 is sent from the hot water supply pipe 3 to the usage section at any time. Moreover, when hot water is tapped, water is supplied from the water supply pipe 2 to the hot water storage tank 1 accordingly. Then, when the detected temperature Ti of the temperature sensor 19 becomes lower than the set temperature Ts by a certain temperature or more, the hot water thermocircuit 27 switches the output switch 27 again.
1,272 and repeat the above operation.

When the outside temperature is low, such as at night in winter, there is a risk that the water in the circulation circuit 4 may freeze. Therefore, the control device 24 causes the following antifreeze operation to be performed even if the operation switch 20 is turned off.

In other words, the antifreeze thermostat 22 or 23 is
When a low temperature below ℃ is detected and turned on, the delay off timer device 28 is energized and the time switch 2 is turned on.
81 is turned on. And the pump control circuit 29
is energized and starts the circulation pump 7, so that water or hot water in the lower part of the hot water tank 1 flows into the circulation circuit 4 from the water outlet 5.

At this time, if the water temperature at the bottom of the hot water storage tank 1 is 6° C. or higher, the antifreeze thermostat 22 or 23 is turned off by the water or hot water in the hot water storage tank 1 flowing into these attachment parts. Therefore, even if the delay-on timer device 30 is energized via the flow switch 9 and the output switch 272, the hot water thermo device 27 will stop operating before the set temperature (10 seconds) of the delay-on timer device 30 has elapsed. However, since the output switches 271 and 272 are turned off, no combustion occurs in the burner 11 of the heating device 10. The circulation pump 7 then stops after the time set by the delay off timer device 28 (45 seconds) has elapsed from the time when the antifreeze thermostat 22 or 23 was turned off. Therefore, even if the circulation pump 7 operates at the minimum flow rate, the water or hot water in the lower part of the hot water storage tank 1 is distributed throughout the circulation circuit 4, and freezing of the entire circulation circuit 4 is prevented.

If the water temperature at the bottom of the hot water storage tank 1 is lower than 6° C., the antifreeze thermostats 22 and 23 will not be turned off even if the water at the bottom of the hot water storage tank 1 is supplied to the circulation circuit 4. In this case, as a matter of course, the output switches 271 and 272 of the hot water thermometer 27 are turned on, so the delay-on timer device 30 and the relay 31 are energized via the flow switch 9 and the output switch 272, and pre-purge is performed. It can be done. Then, when the set time of the delay-on timer device 30 has elapsed, the burner control device 32 is energized and the burner 11 starts combustion. As a result, the water in the hot water storage tank 1 is heated, and when the temperature of the water flowing through the circulation circuit 4 reaches 6°C or higher, the antifreeze thermostat 22,
23 are all turned off. At this time, the hot water thermometer 27 stops operating, so the burner 11 stops combustion. The circulation pump 7 is connected to the burner 11.
When the set time of the delay off timer device 28 has elapsed, the operation is stopped. Therefore, when the water temperature in the lower part of the hot water storage tank 1 is low and the water in the hot water storage tank 1 is not useful for preventing freezing, the burner 11 is used to perform combustion, thereby reliably preventing the water in the circulation circuit 4 from freezing. . Of course, after the combustion of the burner 11 is stopped, the circulation pump 7 is stopped after a delay of the set time of the delay-off timer device 28, so there is no fear that boiling will occur in the heating device 10.

According to this embodiment, two antifreeze thermoses 22 and 23 are installed at different positions in the circulation circuit 4, and the circulation pump 7 is operated by the OR output of these thermometers. By lowering the temperature (2°C in the example), frequent antifreeze operations can be prevented. That is, when hot water is left in the hot water tank 1, the temperature at the attachment part of the antifreeze thermostat 22 is difficult to drop due to heat conduction from the hot water storage tank 1, and the antifreeze thermostat 23, which is close to the heating device 10, prevents the ambient temperature from decreasing. It is sensitively detected and turns on first.
On the other hand, if there is no hot water left in the hot water tank 1, the antifreeze thermostat 22 located below is turned on first. In this way, even if the location in the circulation circuit 4 that cools quickly differs depending on the usage conditions, the two anti-freeze thermoses 22 and 23 accurately detect a drop in ambient temperature, so the setting of the freezing danger temperature is possible. It can be made as low as possible, eliminating unnecessary antifreeze operations. Furthermore, since water or hot water from the hot water storage tank 1 is supplied to the circulation circuit 4 to prevent freezing, there is no need to worry about wasting water or increasing power consumption as in the past, contributing to resource and energy conservation. can.

In addition, in the above-mentioned embodiment, the anti-freezing thermometer is
However, the length of the circulation circuit 4 and the heating device 10
Three or more may be used depending on the mounting position.
In addition, there are various types of anti-freezing thermometers, such as mechanical ones and electronic ones that combine a temperature sensor such as a thermistor with a temperature control circuit. It is only necessary to attach only one to the circulation circuit 4.

(g) Effects of the invention This invention is structured as described above, so
With multiple antifreeze thermostats installed at different locations in the circulation circuit, regardless of whether there is hot water remaining in the hot water tank,
It is possible to accurately detect the temperature at a point in the circulation circuit that is at risk of freezing due to a drop in ambient temperature, and the freezing risk temperature can be set low to eliminate frequent antifreeze operations. Furthermore, by operating the circulation pump with the OR output of multiple anti-freeze thermostats and supplying water from the hot water tank or hot water to the circulation circuit, the water in the circulation circuit is prevented from freezing, making it possible to prevent the water from freezing like in the past. There is no needless discharge or increased power consumption, contributing to resource and energy conservation.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a water heater to which this invention is applied, and FIG. 2 is an electric circuit diagram of a control device that also serves as the antifreeze device shown in FIG. 1. 1...Hot water storage tank, 2...Water supply pipe, 3...Hot water supply pipe,
4... Circulation circuit, 7... Circulation pump, 10... Heating device, 22, 23... Antifreeze thermostat, 24...
...control device (antifreeze device).

Claims (1)

[Scope of utility model registration request] A hot water storage tank with a water supply pipe connected to the bottom and a hot water supply pipe connected to the top, a heating device installed outside the tank,
It has a circulation pump that supplies water from the hot water storage tank to the heating device from the water outlet at the bottom of the hot water storage tank, and a circulation circuit that returns hot water heated by the heating device to the hot water storage tank from the hot water return port at the top of the hot water storage tank. In the water heater equipped with the above-mentioned hot water supply system, a first anti-freeze thermostat is provided in the circulation circuit near the water outlet at the bottom of the hot water storage tank, and a second antifreeze thermometer is provided in the circulation circuit near the heating device and on the inflow side of the heating device. 1. A hot water supply device comprising an anti-freeze device that has an anti-freeze thermometer and operates a circulation pump using the output of one of these anti-freeze thermometers.