JPH0711339B2 - Hot water heating system - Google Patents

Description

The present invention relates to a hot water heating device.

(Prior Art) In a conventional hot water heating device, a heat exchanger and a radiator are connected by a circulation circuit, and hot water is circulated by a pump interposed in the circulation circuit. In controlling the hot water temperature, the temperature at the outlet of the heat exchanger is detected and the proportional valve of the burner for heating the heat exchanger is proportionally controlled so that the temperature becomes constant.

(Problems to be Solved by the Invention) By the way, since the water temperature is low at the time of heating start, the proportional valve has a large opening and burns with a large capacity to make the rise as fast as possible. However, when the load on the radiator is small, the temperature of the hot water returning to the heat exchanger has not dropped too much, and the hot water that has been heated by this large capacity causes the hot water temperature to rise too high, turning off the combustion. It had to be done. When the combustion is turned off, the hot water temperature is lowered, and the combustion is turned on again. However, when the load is small, the flow rate is small and the delay in temperature detection is large, so overshoot and undershoot frequently occur. Therefore, although the rising speed is fast, the hot water discharge characteristics are poor, and it takes a long time for the hot water temperature to stabilize. That is, on the radiator side, the hot air first comes out and then becomes cold, and while repeating this, it becomes an appropriate warm air, which is uncomfortable.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional drawbacks and to provide a hot water heating device that can obtain good hot water discharge characteristics regardless of the size of the load of the radiator, that is, the number of times combustion is turned on and off is small.

(Means for Solving the Problems) In order to achieve the above object, the present invention is characterized by the following configurations. That is, a soft start circuit that gradually increases the combustion amount at the start of heating is provided.

(Operation) Since the amount of combustion starts from a small amount at the start of heating, even if the load on the radiator is small, the warm water returned to the heat exchanger will not suddenly become hot. Therefore, the on / off of combustion is eliminated and the tapping property is improved.

(Example) An example of the present invention will be described with reference to the drawings. Reference numeral 1 is a heat exchanger, 2 is a radiator, and these are connected by a circulation circuit 3. A pump 4 is interposed in the circulation circuit 3. The burner 5 heats the heat exchanger 1, and the combustion amount is controlled by the proportional valve 6. A temperature detector 7 is provided at the outlet of the heat exchanger 1 and detects the temperature of the hot water discharged. Reference numeral 8 denotes a controller, which receives the signal from the temperature detector 7 and controls the proportional valve 6,
An adding circuit 9 that is a soft start circuit that gradually increases the combustion amount at the start of heating, a subtraction circuit 10 that decreases the combustion amount when the set temperature is detected while increasing the combustion amount, and a combustion circuit. A built-in proportional control circuit 11 that starts proportional control when the hot water temperature does not decrease and reaches a certain value while the amount is being reduced. These circuits are composed of a microcomputer, and the flow thereof is shown in FIG.

Next, the operation of the above configuration will be described. When the heating operation start signal is input to the controller 8 (S1), the combustion amount (gas pressure) G is set to the minimum and combustion is started (S2). Next, compare the tap water temperature T _H with the set temperature T _S (S3)
If T _H is low, a constant gas pressure (ΔG) is added every fixed time (S4). When the hot water outlet temperature T gradually rises and reaches the set temperature T _S , the constant gas pressure (ΔG) is subtracted at regular intervals (S5). Then, it is judged whether or not the outlet heated water temperature T _H is lowered (S6), and if it is lowered, the value is added again (S7).
If the hot water outlet temperature T _H does not decrease, it is determined whether or not the gas pressure G at that time is a predetermined value that allows the proportional control to be shifted (S8). If it is not the predetermined value, the subtraction is continued (S5) and the predetermined value is reached. If so, the control shifts to proportional control.

Therefore, as shown in FIG. 3, the tap water temperature reaches the set temperature with smooth characteristics regardless of the size of the load. That is, when the load is small, even if the initial heated water returns to the heat exchanger 1, the gas pressure at that time has not yet reached its maximum, and the set temperature will not be significantly exceeded. Moreover, since the gas pressure is forcibly reduced when the set temperature is exceeded, the overshoot amount can be further reduced.

It should be noted that when the load is large, the time required for the hot water temperature to reach the set temperature is longer than that for the conventional one, but there is no significant difference in the time until the hot water temperature stabilizes, and there is no inconvenience in actual use.

(Effects of the Invention) As described above, according to the present invention, since the combustion amount is gradually increased at the start of the heating operation, good hot water discharge characteristics can be obtained regardless of the load of the radiator, and the number of combustion on / off times can be increased. The durability of the gas valve and the igniter is improved, and the usability is improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of the present invention, FIG. 2 is a control flowchart, and FIG. 3 is a time chart of gas pressure and tapping temperature. FIG. 4 is a time chart of conventional gas pressure and hot water temperature. 1 ... Heat exchanger 2 ... Radiator 3 ... Circulation circuit 4 ... Pump 5 ... Burner 6 ... Proportional valve 7 ... Temperature detector 8 ... Controller 9 ... Soft start circuit

Claims (1)

[Claims] 1. A heat exchanger and a radiator are connected by a circulation circuit,
A hot water heating device that circulates hot water with a pump interposed in a circulation circuit, comprising a soft start circuit that gradually increases the amount of combustion at the start of heating.