JPS6238621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to a control device for a hot water boiler having anti-freezing function.

(b) Prior art The conventional control devices for this type of hot water boiler are as follows:
One thing was hot.

Use an antifreeze valve to drain water from areas that are at risk of freezing. Or run hot water over the area.

Even when the boiler's hot water is not in use, if there is a risk of freezing, set the temperature control device that adjusts the boiler's hot water to a lower temperature.
Operate the boiler solely for the purpose of preventing freezing.

Install antifreeze heaters in areas where there is a risk of freezing, and energize the heaters when the temperature becomes low.

In the above-mentioned method, the cost of the antifreeze valve is high, and it may not work properly unless fluid flow and pressure are taken into account.In the case of the water drain method, it is also necessary to consider what to do with the drained water, so it is not a good method. No, no.

The method of lowering the set temperature of a temperature control device is that it is structurally difficult to completely match the position of the temperature detection element that detects the water temperature with the location where there is a risk of freezing, so At the same time as the boiler was running, there were cases where it was not able to sufficiently prevent freezing.

Anti-freeze heaters are expensive, difficult to install when the area that requires anti-freezing is large, and requires heat-resistant heater wiring when the area is close to the combustion area.

(c) Purpose of the Invention This invention was made to solve the problems of the prior art described above, and aims to prevent freezing by operating the boiler for a short time so that freezing can be prevented reliably at low cost. The purpose is to ensure that it is done efficiently.

(D) Structure of the Invention This invention has a hot water temperature detector for detecting the hot water temperature in the hot water storage tank and a variable resistance section for setting the temperature in the input section, compares the hot water temperature with the set temperature, and determines the hot water temperature. Equipped with a temperature control device that activates the combustion device when the temperature is lower than a set temperature, and an anti-freezing thermometer installed in a place where the hot water boiler is prone to freezing, or a place susceptible to the influence of the temperature of the combustion device and outside air, This structure has an anti-freeze thermo contact that closes when the anti-freeze thermo detects a freezing dangerous temperature in parallel with the resistance of the variable resistance section.

(E) Embodiment Hereinafter, an embodiment of the present invention shown in the drawings will be described in detail. FIG. 1 shows a hot water boiler to which this invention is applied. In the figure, 1 is a push-up type hot water storage tank with a water supply pipe 2 connected to the bottom and a hot water outlet 3 at the top, 4 is a heat exchanger disposed below the hot water storage tank 1, and 5 is a push-up hot water storage tank. A descending pipe 6 leads the water in the lower part of the hot water storage tank 1 to the inlet side header 4a of the heat exchanger 4, and a rising pipe 6 returns the hot water heated by the heat exchanger 4 from the outlet side header 4b to the center of the hot water storage tank 1. 7 is a combustion device that heats the heat exchanger 4 with a burner 8; 9 is a hot water temperature thermistor as a hot water temperature detector that detects the hot water temperature slightly above the connection position of the rising pipe 6 of the hot water storage tank 1; and 10 is a heat exchanger. An antifreeze thermometer (temperature detection unit) attached to the downcomer pipe 5 near the header 4a on the inlet side of the vessel 4 and detects the water temperature in the downcomer pipe 5 and the outside temperature; This is a temperature control device that starts and stops the burner 8 by inputting the signal from the temperature setting volume 12 and the signal from the temperature setting volume 12.

As shown in FIG. 2, the temperature control device 11 includes a series circuit of a bridge circuit 16, an operational amplifier 17, a relay 18 for driving the burner 8, and an NPN transistor 19 between bus bars 14 and 15 connected to a DC power source 13. It is equipped with The bridge circuit 16 includes a series circuit of a variable resistance section VR consisting of a resistor 20, a resistor 21, and a temperature setting volume 12, a hot water temperature thermistor 9, a series circuit of resistors 22 and 23, and a resistor 21.
and a temperature setting volume 12 and an antifreeze thermostat 10A connected in parallel. operational amplifier 17
connects the non-inverting input terminal 171 to temperature setting volume 1.
2 and the hot water temperature thermistor 9, the inverting input terminal 172 is connected to the intermediate connection point 25 between the resistors 22 and 23, the output terminal 173 is connected to the base of the transistor 19 via the resistor 26, and the output terminal A feedback resistor 27 is connected between the input terminal 173 and the non-inverting input terminal 171. In addition, in the temperature control device 11 described above, the set temperature T _S is set in the range of T _SL (e.g., 30°C) to T _SH (e.g., 60°C) by adjusting the temperature setting volume 12, and the antifreeze thermostat 10
A closes when the detected temperature becomes T1 (eg, 2°C) or lower, and opens when the detected temperature becomes T2 (eg, 6°C) or higher, which is higher than T1. Since the resistor 21 and the temperature setting volume 12 are short-circuited while the antifreeze thermostat 10A is closed, the set temperature T _S of the temperature control device 11 becomes T _SM higher than the normal maximum set temperature T _SH .

In the device of this embodiment described above, the antifreeze thermostat 10A is normally open, and the hot water temperature T _W detected by the hot water temperature thermistor 9 is compared with the set temperature T _S determined by the adjustment position of the temperature setting volume 12. Accordingly, the temperature control device 11 starts and stops the burner 8.
That is, when T _W is lower than T _S , the voltage at node 24 is higher than the voltage at node 25 and the operational amplifier 17
Transistor 19 becomes conductive due to the output of , relay 18 is energized, and burner 8 performs combustion. During combustion, the water in the hot water storage tank 1 is circulated to the heat exchanger 4 due to the circulation effect due to the difference in specific gravity between the hot water and the hot water, and hot water is sequentially stored from the top of the hot water storage tank 1. When the hot water temperature thermistor 9 detects a hot water temperature higher than the set temperature T _S , the voltage at the connection point 24 becomes lower than the voltage at the connection point 25 , the transistor 19 is cut off by the output of the operational amplifier 17 , and the relay 18 is deenergized. The burner 8 is turned off and combustion of the burner 8 is stopped. In this way, the hot water stored in the upper part of the hot water storage tank 1 is discharged from the hot water outlet 3 at any time, and the lower part of the hot water storage tank 1 is replenished with new water correspondingly.

When the outside air temperature is low, the temperature at the bottom of the hot water boiler rapidly decreases while the burner 8 is stopped. especially,
The temperature of the downcomer pipe 5, which has a small heat capacity, is most likely to drop, and the antifreeze thermostat 10A closes when it detects a temperature below T1. When the antifreeze thermostat 10A closes, the resistor 21 of the bridge circuit 16 and the temperature setting volume 12 are short-circuited, so the set temperature T
_S becomes T _SM higher than the maximum set temperature T _SH . Therefore, even if the hot water detected by the hot water temperature thermistor 9 is boiling at the highest temperature setting, since T _W <T _SM , the relay 18 is energized and the burner 8 is ignited. Due to combustion, the heat exchanger 4 boils in a few seconds, creating a circulation in which water from the hot water storage tank 1 flows into the downcomer pipe 5.
immediately detects a temperature higher than T2, opens the burner, and stops combustion in burner 8.

As described above, this embodiment has an antifreeze thermometer 10.
A detects the temperature of the downcomer pipe 5 with the highest risk of freezing in the hot water boiler, and from the time the temperature of this part reaches T1 until the temperature of T2, which is higher than T1, the resistor 21 and temperature setting volume are controlled. 12 with a 10A antifreeze thermometer, and set the set temperature T _S to T _S
M is used to forcibly burn the burner 8 to prevent freezing, so there are the following advantages.

○B Just add one or more freeze prevention thermos 10 such as a temperature-sensitive reed switch to the input part (bridge circuit 16) of the temperature control device 11, or if necessary, freeze prevention can be achieved at low cost. can.

Since freezing is prevented by burning the Ro Burner 8, there are no problems associated with conventional anti-freeze valves or anti-freeze heaters.

○C Since the burner 8 is fired by directly detecting the temperature in a place where there is a risk of freezing, even if the hot water temperature in the hot water storage tank 1 is high and the burner 8 does not burn under normal settings, the temperature in a place where there is a risk of freezing is detected (descending). The pipe 5) can be heated efficiently in a short time, and
There is no need to worry about prolonging boiler operation to prevent freezing longer than necessary. In particular, in this embodiment, the downcomer pipe 5, the riser pipe 6, and the heat exchanger 4 are at risk of freezing.
Since the heat capacity is small, the time for burning the burner 8 is short, from several seconds to several tens of seconds, and the fuel consumption is extremely small.

(f) Effects of the Invention As explained above, the present invention uses inexpensive parts (temperature detection By simply adding the input section) to the input section of the temperature control device, antifreeze operation can be performed more reliably and efficiently, and excellent effects can be achieved, such as saving fuel consumption and reducing costs.

[Brief explanation of the drawing]

The figure shows an example device of the present invention,
FIG. 1 is an explanatory diagram of the overall configuration, and FIG. 2 is an electric circuit diagram. 7...Combustion device, 9...Water temperature thermistor (water temperature detector), 10...Anti-freezing thermometer, 10A...
Freeze prevention thermo contact, 11...Temperature control device,
VR...Variable resistance section.

Claims (1)

[Claims] 1 The input section includes a hot water temperature detector that detects the hot water temperature in the hot water storage tank and a variable resistance section for temperature setting, and compares the hot water temperature with the set temperature, and when the hot water temperature is lower than the set temperature, the combustion device is activated. The system is equipped with a temperature control device that operates the system, and an antifreeze thermometer installed in areas of the hot water boiler that are prone to freezing, or in areas that are susceptible to the effects of the combustion equipment and outside air temperature.This antifreeze thermometer detects freezing temperatures. A control device for a hot water boiler, characterized in that an antifreeze thermo contact that closes when the circuit is closed is provided in parallel with a resistance of a variable resistance section.