JPH0413015A - Circulation type hot water supplying apparatus - Google Patents

Abstract

PURPOSE:To reduce igniting and extinguishing frequencies by providing a capacity fixing circuit for burning at a lower predetermined temperature or lower than a hot water supplying set temperature or in a fixed small capacity up to the lapse of a predetermined time at the time of insulation heating, and a proportional control circuit for burning at a predetermined temperature or in a variable capacity if it exceeds a predetermined time. CONSTITUTION:A predetermined temperature comparing circuit 27 compares a detection temperature with a lower predetermined temperature than a hot water supplying set temperature, controls at the predetermined temperature or lower by a capacity fixing circuit 28, and controls by a proportional control circuit 29 if it exceeds the predetermined temperature. The circuit 28 so controls a load as to maintain the opening of a proportional control valve 22 constant and to burn in a small capacity by opening only a capacity switching solenoid valve 18. An initial time discriminator 26 burns under a proportional control due to necessity of a rapid rise at the time of an initial ignition. When second or following ignition commands are fed, a capacity control circuit 30 limits the maximum value of the burning capacity, for example, to 70%, and the circuit 29 is limited to 70%. Accordingly, the burning time is increased, and hence frequencies of igniting and extinguishing are reduced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a circulating water heater.

(Conventional technology) Conventionally, water heaters have only had a single hot water supply pipe extended from the water heater and a hot water supply pipe attached to the end of the pipe, but the distance between the water heater and the hot water supply pipe has been limited. Under conditions where the water heating time is long, it is not only inconvenient to use, as it takes a long time for hot water at the desired temperature to actually come out after opening the hot water supply door, but also during the initial period of use.
Previously, when hot water supply was not in use, low-temperature water that had remained in the hot-water supply piping and was being cooled would come out, and this low-temperature water had to be thrown away (this water is called waste water), which was an inconvenience.

Therefore, in order to eliminate such inconveniences and inconveniences when using hot water supply, a type of water heater has been developed in which hot water is constantly circulated between the water heater and the hot water supply cylinder using a circulation pump. This is as shown in Figure 6.
A forced circulation pump 06 is interposed in the middle of a circulation pipe 03.04 provided between the hot water supply system 1 and the hot water supply cylinder 02. When hot water supply is not in use, the hot water in the circulation circuit is kept warm and hot water is immediately released when hot water supply is used.

(a5 problem to be solved by the invention) In order to keep and heat the hot water in the circulating circuit when the hot water supply is not in use, there is a method using an electric heater 05 as shown in FIG. Official gazette and Actual Publication 5
There is a method that uses the amount of heat produced by the ignition and extinguishing of combustion in a water heater, as shown in Japanese Patent No. 7-47618.

However, those using an electric heater require a separate heat-retaining tank 07 for heating hot water with the electric heater, and have the disadvantage that the water heater cannot be made compact. On the other hand, those that use the amount of heat produced by point-extinguishing combustion do not require a heat insulating tank and are therefore more compact, but the frequent point-and-extinguishing of combustion causes issues with combustion noise and the durability of parts such as fuel system valves. Ta.

(Means for Solving the Problems) An object of the present invention is to provide a circulating water heater that reduces the frequency of combustion and extinguishing, thereby reducing combustion noise and improving the durability of solvent-based parts. It is characterized by the following configuration. In other words, a hot water circulation pump is installed in the middle of a hot water circulation pipe installed between a water heater having a proportional control valve and a hot water supply system, and a temperature sensor is installed, and the temperature is measured based on the temperature detected by the temperature sensor. In a circulating water heater that turns on and off the combustion in the water heater, there is a fixed capacity circuit that burns at a fixed low capacity until the temperature reaches a predetermined temperature lower than the hot water supply setting temperature or until a predetermined time has elapsed during the heating process. Alternatively, if the predetermined time is exceeded, proportional 1 burns at a variable capacity using proportional I control based on the deviation from the hot water set temperature.
A combustion control device having a 111 circuit is provided.

Further, a capacity limiting circuit is provided to limit the maximum value of combustion capacity during proportional combustion.

Furthermore, a forced combustion circuit is provided in which the initial combustion is controlled only by the proportional 11m circuit.

(Function) When starting thermal insulation heating, the water in the hot water circulation piping is cold for the first time, so the capacity is controlled only by the proportional control circuit by the initial determination circuit, and the temperature is quickly raised to the hot water supply set temperature.

Then, when the hot water in the pipes has cooled down and a second or subsequent heat retention is performed, the capacity fixed circuit burns at a fixed small capacity until the hot water reaches a predetermined temperature lower than the hot water supply setting temperature or until the hot water continues for a predetermined time.

Therefore, the combustion time becomes longer. When the predetermined temperature (A) and (C) reach a predetermined time, proportional control is performed. At this time, the temperature deviation is small, the dip proportional control valve is throttled, and the baking time also becomes longer. Therefore, the total combustion time becomes longer, the period from one ignition to the next ignition becomes longer, and the number of ignition and extinguishing times of combustion is reduced.

Further, at the 19th time when the second and subsequent heat-retention heating is performed, the maximum value of the combustion capacity may be controlled by the limiter circuit. In other words, if the temperature deviation is large, the ζ2If example control circuit tries to cause combustion at high capacity, but since this causes the hot water temperature to rise immediately, it restricts the heat exchanger and slows down the rise in hot water temperature. I'll take it because it makes me want to do it. Therefore, the combustion time to reach the hot water supply set temperature becomes longer, the cycle from ignition to the next ignition becomes longer, and the number of times combustion is turned on and off is reduced.

(Example) In FIG. 1, 1 is a water heater, and 2 is a hot water heater. 3.4 is the heat exchanger 8 of the water heater 1 and the hot water heater 2
This is a circulation piping provided between the two, and a circulation pump 6 is interposed therebetween. 9 is a water supply pipe connected to city water, which includes a check valve 10, a water flow sensor 11, and an inlet water temperature sensor 12.
is arranged and connected to the heat exchanger 8. The return pipe 4 of the circulation pipe is connected downstream of the check valve 10 of the water supply pipe 9. 13 is a hot water temperature sensor installed in the outgoing pipe 3; 14
is the water amount wIr1s valve.

15 and 16 are check valves, 15 is for the outgoing pipe 3, and 16 is for the return pipe 4.
There is no intervention. Reference numeral 17 denotes a group of burners for heating the heat exchanger 8, which is arranged corresponding to the gas passages branched by the capacity switching fr solenoid valves 8, 19, 20, and 21. 22 is a proportional control valve provided upstream of the electromagnetic valve group, and 23 is a former electromagnetic valve. and the solenoid valve and proportional control valve 22
is controlled by a control device 24.

FIG. 2 shows a main block diagram inside the control device 24.
The II system W24 is mainly composed of a microcomputer, and performs control as a normal water heater, and performs TSM such as circulation and heat retention heating as a circulating water heater. Reference numeral 25 denotes a comparison circuit that compares the incoming water temperature sensor 12 with a hot water supply temperature set by a 4 degree setting device (not shown) and outputs a command to turn off the hot water during heat retention heating.

Of course, hysteresis is provided for the temperature at which the fire is turned on and extinguished.

Reference numeral 26 denotes a first time determination circuit, which determines whether or not the ignition command during thermal insulation heating is the first time, and if it is the first time, only combustion control is performed by a proportional control circuit 29, which will be described later. 27
is a predetermined temperature comparison circuit, which compares the detected temperature with a predetermined temperature lower than the hot water supply setting temperature, and when the temperature is lower than the predetermined temperature, the capacity fixed circuit 2 is activated.
8 is performed, and when the temperature exceeds a predetermined temperature, control is performed by the proportional control circuit 29. The capacity fixing circuit 28 controls the load so as to keep the opening degree of the proportional control valve 22 constant and to perform small capacity combustion in which only the capacity cut-off valve I8 is opened. The proportional 1iI1g1 circuit 29 controls the load by varying the opening degree of the proportional w4 control valve 22 through proportional control based on the deviation between the detected temperature and the hot water supply set temperature.

Reference numeral 30 denotes a capacity limiting circuit, which controls the load by limiting the maximum value of the combustion capacity when combustion is performed by proportional control during the second and subsequent combustions.

In addition, in the case where the timing for switching control from the capacity fixing circuit 28 to the two proportional iI4 control circuits is determined by time,
The predetermined temperature comparison circuit may be replaced with a timer.

Next, an explanation will be given of the operation of the above-mentioned configuration during heat retention and heating.

When the water is turned on, the circulation pump 6 is first activated, and the incoming water temperature sensor 12 detects the water temperature. Initially, the water temperature is lower than the hot water supply setting temperature, so the comparison circuit 25 outputs an ignition command.

Then, the first time determination circuit 26 determines whether or not this ignition command is the first time after turning on the insulation heating start switch, and if it is the first time, outputs a control start output to the proportional control circuit 29.

Since the detected water temperature is low, the proportional control circuit 29 causes the burner 7 to burn at its maximum capacity, quickly raising the temperature of the circulating water to the hot water supply set temperature. Therefore, even if you use the hot water supply a short time after turning on the switch, hot water will come out without any waste water.

When hot water is being used, it is the same as a conventional water heater, and the incoming water temperature sensor 1
2 detects the temperature of water coming in from city water, the water flow sensor 11 detects the water flow rate, and the proportional control valve 22 and the solenoid valves 18 to 21 control so that combustion is performed at a combustion capacity determined from these and the hot water supply setting temperature. In addition, the hot water temperature sensor 13 detects the hot water temperature, and if there is a deviation from the hot water supply set temperature, the combustion capacity is corrected to eliminate this deviation, and hot water at the hot water supply set temperature is discharged from the hot water supply cooker 2. Once hot water supply is finished, combustion will stop.

If the #ij temperature in the pipe decreases while the hot water supply is stopped, this is detected by the incoming water temperature sensor 12 or the outgoing hot water temperature sensor 3, and the comparison n path 25 outputs an ignition command. Initial judgment amount FI
! Since this is the second time, i26 activates the predetermined temperature comparison circuit 27.

The predetermined temperature comparison circuit 27 determines that the detected water temperature is the hot water supply setting temperature T,
Lower predetermined temperature T. If the following is true, the ability fixing circuit 28
control. If the capacity at this time is set to the minimum value, for example, the proportional control valve 22 is set to the minimum opening, and the solenoid valve 1 is set to the minimum opening.
Open only 8 and burn with only one burner. Therefore, since the amount of heating is small, the rate of rise in the temperature of the water is slow (see Figure 3). and the predetermined temperature T. When the water temperature rises, the predetermined temperature comparison circuit 27 switches control to the proportional control circuit 29. At this time, the deviation from the set temperature T has already become small, so the opening degree of the proportional 8m valve 22 is not large, and 1,'! ! The rise in temperature will also be gradual. When the detected hot water temperature reaches the set hot water supply temperature T, the comparison vgJ path 25 outputs a fire extinguishing command to extinguish the fire. Therefore, the ignition time is longer than in the conventional case (see Fig. 5), and the frequency of spot extinguishing is correspondingly reduced.

Next, the capacity control circuit 30 will be explained. The first time, as mentioned above, a quick rise is required, so combustion is performed using proportional control. When the second and subsequent ignition commands are received, the initial determination circuit 26 activates the capacity limiting circuit 30. The capacity limiting circuit 30 is
The maximum combustion capacity is limited to, for example, 70%.

Therefore, when the detected water temperature is low, the proportional control circuit 29
I try to output 0% output, but it turns out to be 70%.
! It will be done. Therefore, as shown in Figure 4, the rate of increase in ms is slower than in the conventional case (see Figure 5), which starts at 100%, and in this case as well, the time for ignition and combustion is longer. It is. Therefore, the period of spot extinguishing becomes longer and the frequency of spot extinguishing becomes less.

Furthermore, in the case where a timer is used instead of the predetermined temperature comparison circuit 27, the capacity fixing circuit 2B performs 1ilIlliI for a certain period of time after ignition, and then the proportional M control circuit 2B performs 1ilIlliI.
9, and is effective in extremely cold regions where it is difficult to raise the temperature with a small capacity.

Although the operation of the circulation pump 6 may be stopped at the same time as the fire is extinguished, it is better to keep it running during the time when the hot water circulates in the pipe after the fire is extinguished, to suppress after-boiling due to combustion and to reduce the temperature of the water inside the pipe. It is effective because it ensures uniformity.

(Effects of the Invention) As described above, the present invention suppresses the combustion ability during heat retention and increases the combustion time. By reducing the burning noise and reducing the frequency of ignition and extinguishing, the durability of the parts can be improved.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of main parts. Figures 3 and 4 are graphs showing the relationship between capacity (a) and hot water temperature (b) of the present invention, and Figure 5 is a graph showing the relationship between capacity (a) and hot water temperature (b) of the conventional example. It is a graph. FIG. 6 is an overall configuration diagram of a conventional example. 1...Water heater 2...Hot water supply system 3.4...Hot water circulation piping 6...Circulation pump 12. 24 ・ 26 ・ 28 ・ 29 ・ 30 ・ 3... Temperature sensor/combustion control device - initial judgment circuit/capacity fixing circuit/proportional side IB circuit/capacity limiting circuit

Claims (3)

[Claims] (1) In the middle of the hot water circulation piping installed between the water heater with a proportional control valve and the hot water supply system, a hot water circulation pump is installed and a temperature sensor is installed, and the temperature detected by the temperature sensor is In a circulating hot water system that turns on and off the combustion in the water heater based on the heat retention system, there is a fixed capacity circuit that burns at a fixed low capacity until the combustion during heating is lower than a predetermined temperature lower than the hot water supply setting temperature or until a predetermined time elapses, and Alternatively, a circulation type hot water supply device characterized in that it is provided with a combustion control device having a proportional control circuit that burns the hot water at a variable capacity by proportional control based on the deviation from the hot water supply setting temperature when a predetermined time is exceeded. (2) In the middle of the hot water circulation piping installed between the water heater with a proportional control valve and the hot water supply system, a hot water circulation pump is installed and a temperature sensor is installed, and the temperature detected by the temperature sensor is In a circulating hot water system that turns on and off the combustion in the water heater based on the heat retention temperature, the proportional control circuit performs combustion during heat retention heating with a variable capacity using proportional control based on the deviation between the detected temperature and the hot water supply setting temperature, and the proportional combustion What is claimed is: 1. A circulating water heater comprising a combustion control device having a capacity limiting circuit that limits the maximum value of the combustion capacity of the water heater. (3) The circulating hot water supply apparatus according to claim 1 or 2, further comprising an initial determination circuit that causes only combustion control by a proportional control circuit to be performed for the first combustion during heat retention heating.