JPS649536B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved control device for a hot water heater having an indirect heat exchanger.

Conventionally, in hot water heaters equipped with indirect heat exchangers using gas proportional control valves, the temperature of the hot water supply was obtained by controlling the temperature of the heating circulation water, so it was not possible to control the temperature of the hot water supply arbitrarily. It was not possible to obtain the desired temperature for hot water supply, and the desired temperature had to be achieved manually by mixing with water. In addition, although the temperature of hot water can be controlled to some extent by controlling the temperature of circulating heating water, as shown in Figure 1,
When the amount of hot water supplied was increased, the temperature A of the circulating heating water decreased, and since heat exchange was performed by indirect heating, the hot water supply temperature B also further decreased, which was not desirable in terms of hot water supply performance. Furthermore, the temperature of the hot water supply varies significantly depending on the temperature of the water supplied to the hot water supply side, and therefore the mixing ratio with water also changes each time, making it inconvenient to use.

In order to eliminate the drawbacks of the conventional example, the present invention provides temperature sensors for detecting the respective temperatures of heating circulating water and hot water supply, and controls the temperature by switching the temperature sensors during each operation of heating and hot water supply. In this way, the present invention provides a control device for a hot water supply/heater that can obtain a stable hot water temperature not only for space heating but also for hot water supply. Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 2 shows one embodiment of the present invention.
1 is a heat exchanger that heats circulating water for heating, 2 is a heating coil for hot water supply, 3 is a temperature circulation pump, 4 is a tank for makeup water, 5 is a return pipe for heating, and 6 is an outgoing pipe for heating that includes a radiator, etc. Connected. 7 is a heating coil 2 for hot water supply
8 is a hot water tap; 9 is a first temperature sensor installed near the outlet of the heat exchanger 1 to detect the temperature of the circulating heating water; 10 is near the outlet of the hot water heating coil 2; 11 is a temperature detection unit that outputs a signal corresponding to the detected temperature of the first or second temperature sensor; 12 is a signal corresponding to a preset temperature; 13 is a temperature detection unit 11 that outputs a temperature setting unit that outputs
14 is an amplification control section, 15 is a solenoid valve, 16 is a pressure regulator, 1
7 is a proportional gas control valve, and 18 is a gas burner.

Next, the operation will be explained. First, in the case of heating operation, the comparing unit 13 compares a signal corresponding to the temperature set in the temperature setting unit 12 according to the heating load and a signal corresponding to the temperature detected by the temperature sensor 9,
Based on the comparison signal, the proportional control valve 17 is controlled to proportionally control the combustion amount of the gas burner 18, thereby controlling the temperature of the heating circulating water. In addition, in the case of hot water supply operation, the temperature detecting section 11 is switched and connected to the temperature sensor 10 by a hot water supply flow switch provided in the middle of the water supply pipe 7, and a signal corresponding to the preset hot water temperature is sent to the temperature setting section 12. The temperature detected by the temperature sensor 10 is compared with a signal corresponding to the detected temperature, and the proportional control valve 17 is controlled based on this comparison signal to proportionally control the combustion amount of the gas burner 18, thereby controlling the hot water temperature.

FIG. 3 shows a comparison of the resistance-temperature characteristics of the first temperature sensor 9 and the second temperature sensor 10, where C is the characteristic of the temperature sensor 9 and D is the characteristic of the temperature sensor 1.
It is a characteristic of 0. Comparing the B constant and thermal time constant of temperature sensor 10 with those of temperature sensor 9, it is found that the B constant and thermal time constant of temperature sensor 10 are approximately 1/1
It is made smaller to 1.5 to 1/2 to give linearity to characteristic D and improve thermal response.
Thereby, the sensitivity and responsiveness of the combustion amount proportional control valve performance to the temperature of the proportional control valve 17 can be increased. Therefore, the combustion amount control characteristic of the burner 18 corresponding to the load and the heat exchange efficiency between the heating temperature and the hot water supply temperature are improved, and as shown in FIG. 4, the temperature drop with respect to the increase in the hot water supply amount can be reduced.
Furthermore, even when the set hot water temperature is changed, the temperature drop with respect to an increase in the amount of hot water supplied is extremely small.

Figure 5 shows the relationship between the temperature detected by the temperature sensor and the combustion amount controlled with respect to this detected temperature, and compares E in the conventional case and F in the case of the device of the present invention. It is. In the case of the conventional example, E is detected by the temperature sensor 9, so the sensitivity is low;
For example, the combustion amount controlled for the detected temperature t _p is I _E
Very few. Therefore, as shown in FIG. 1, the temperature decrease becomes large. In particular, this effect is large when the hot water temperature is obtained by indirect heating, and if it is desired to set the hot water temperature low by lowering the heating temperature, the temperature drop will be even greater, as shown in the characteristic at the left end of FIG. 5. This is because the temperature sensor 9 has a quadratic curve in the resistance-temperature characteristic shown in FIG.
In order to solve this problem, the comparison section 13 and the amplification control section 1
There is a way to deal with this by increasing the circuit gain in step 4, but since the resistance-temperature characteristic of temperature sensor 9 is a quadratic curve, if the temperature drop on the low temperature side is reduced,
On the contrary, the sensitivity of the temperature-combustion amount characteristic on the high temperature side becomes too high, and the change in combustion amount with respect to temperature changes becomes large, which may cause oscillation or on-off operation of the proportional control valve 17, which is a problem.

However, as shown in FIG. 5, by providing the temperature sensor 10 and providing linear resistance-temperature characteristics as in the present invention, the sensitivity of the temperature-combustion amount characteristic is increased, and the detected temperature t The combustion amount for _p is I _F
In addition, even when the temperature is set at a low temperature, a temperature-combustion rate characteristic with almost the same slope can be obtained. Therefore, it is possible to obtain a hot water supply temperature characteristic with an extremely small temperature drop as shown in Fig. 4. can.

FIG. 6 shows a specific example of the control circuit according to the present invention, where 9 and 10 are the temperature sensors shown in FIG. 2, 19 is a commercial power source, 20 is a power switch, and 21
A transformer provides low pressure on the secondary side. 22 is an operation switch, 23 is a full-wave rectifying bridge diode, 24 is a smoothing capacitor, 25 is a limiting resistor, and 26 is a constant voltage diode to obtain a constant voltage power source. 27, 28, and 29 are resistors, which constitute part of the bridge side of the temperature setting section and the temperature detection section. 30
is a hot water supply flow switch such as a water pressure responsive switch installed in a hot water supply waterway, and has a temperature sensor 9 for heating on the B contact side and a temperature sensor 10 for hot water supply on the A contact side.
and a variable resistor 31 for temperature adjustment. 34
is a comparison amplifier, 35 is a gain resistor, 36,3
7 and 39 are resistors, 38 is a driving transistor,
40 is a coil of the proportional control valve 17, and 41 is a reverse voltage prevention diode.

With the above circuit configuration, the temperature detection section 1 shown in FIG.
1, temperature setting section 12, comparison section 13, amplification control section 1
4th prize is included. Then, the hot water supply flow switch 30 is automatically switched in response to heating operation and hot water supply operation, the two input levels of the comparison amplifier 34 are compared, and the current flowing through the coil 40 of the proportional control valve is controlled by this comparison signal. . In this way, the present invention is designed to obtain good hot water temperature characteristics by utilizing the characteristics of the temperature sensors 9 and 10, respectively, although the circuit gain does not change during either heating or hot water supply. be. In addition, when changing the hot water temperature, the resistance value of the variable resistor 31 connected in series to the temperature sensor 10 may be adjusted.

FIG. 7 compares the state of change in the temperature of hot water when the amount of hot water supplied is changed between G in the conventional example and H in the case of the apparatus of the present invention. It can be seen that in the case of H in the case of the apparatus of the present invention, the fluctuation in the hot water temperature is extremely small.

As described above, the present invention has the following excellent effects.

(b) Separate temperature sensors are installed on the heating circulating water side and the hot water supply side, which prevents significant changes in the hot water temperature when the amount of hot water supply changes or when the temperature of the heating circulating water changes. In addition, it is possible to arbitrarily set the hot water temperature and easily obtain hot water at a desired temperature without mixing water as in the conventional example, which has the advantage of further improving usability.

(b) Since the hot water temperature is directly detected by the second temperature sensor, stable hot water temperature control can be obtained, and arbitrary temperature setting control is possible.

(c) Heating and hot water supply are automatically switched, and when hot water is being supplied, the hot water temperature is directly detected and the amount of combustion is controlled, so the response is quick and the time it takes for the hot water temperature to stabilize is shortened.

(d) Since the combustion amount is controlled by the same control device during both heating and hot water supply, there are advantages such as lower cost.

(e) Temperature sensors with different temperature characteristics are provided on the heating circulating water side and the hot water supply side, so it is possible to perform control with little change in hot water temperature in response to changes in the amount of hot water supplied and changes in the heating load.

(f) Since the first and second temperature sensors are connected in parallel, the hot water supply flow switch automatically switches the sensors when hot water is being used, and the hot water temperature can be adjusted from a high temperature close to the heating set temperature to a low temperature. Since the temperature of the hot water can be controlled, there is no need to mix it with water.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between hot water supply amount and hot water temperature in a conventional example, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a characteristic diagram of a temperature sensor, and FIG.
Figure 5 shows the relationship between the hot water supply amount and hot water temperature of the device of the present invention, Figure 5 shows the relationship between the detected temperature and the amount of combustion controlled thereby, and Figure 6 shows a specific example of the present invention. FIG. 7 is a circuit diagram showing the fluctuation state of the hot water temperature when the amount of hot water supplied is changed. 1...Heat exchanger, 2...Hot water heating coil, 9...
...first temperature sensor, 10...second temperature sensor, 11...temperature detection section, 12...temperature setting section,
13... Comparison section, 14... Amplification control section, 17...
Proportional gas control valve, 18... Gas burner, 31...
... Variable resistor, 34 ... Comparison amplifier, 40 ... Coil of proportional control valve 17.

Claims (1)

[Claims] 1. In a hot water heater equipped with an indirect heat exchanger having a heating coil for hot water supply in the heating circulating water passage, the first temperature sensor 9 is provided on the heating circulating water side to detect the temperature of the heating circulating water. And this first
The temperature change in the resistance-temperature characteristic is determined by the temperature sensor.
Almost linear over a wide range of hot water temperatures,
a second temperature sensor 10 provided on the hot water outlet side to detect the temperature of the hot water;
a temperature detection section 11 that outputs a signal corresponding to the temperature detected by the temperature sensor; a temperature setting section 12 that outputs a signal corresponding to a preset temperature; and a temperature detection section 12 that outputs a signal corresponding to the temperature detected by the temperature sensor; a comparison section 13 that compares and outputs a comparison signal; an amplification control section 14 that amplifies the comparison signal; and a proportional gas control valve 17 that proportionally controls the amount of gas supplied to the gas burner based on the output signal of the amplification control section. A water supply flow switch 30 is connected to the first temperature sensor 9 during heating, and switches from the first temperature sensor 9 to the second temperature sensor 10 according to the hot water flow to control the hot water temperature during hot water supply. A control device for a hot water heater, characterized in that: