JPH01210754A - Controller of forced combustion type hot water feeder - Google Patents

Abstract

PURPOSE:To exhaust drain and protect a hot water feeder by shutting the supply of fuel by the use of an electromagnetic valve while continuously actuating an air blower in the case where steam produced together with combustion is cooled and drain is produced without sufficiently heating water which is passed through a heat exchanger. CONSTITUTION:A controller of the hot water feeder consists of electromagnetic valves 21, 22 and a proportional valve 23 provided in a fuel supply pipe 20 for a burner 11, an air blower 12, a heat exchanger thermistor 37 for detecting water temperature flowed out from a heat exchanger 32, and a controlling means 40. When the water temperature flowed in the heat exchanger 32 is low and the heating quantity of the burner 11 is insufficient because of a large quantity of feed hot water, the water temperature flowed out from the heat exchanger 32 is lowered. The water temperature is detected by the heat exchanger thermistor 37. In the case where the temperature detected is not higher than the prescribed temperature, steam produced together with combustion is cooled and condensed by the water in the heat exchanger 32 to be drain. The controlling means 40 closes the electromagnetic valves 21, 22 and the air blower 12 is actuated to exhaust drain.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a combustion water heater that heats water passing through a heat exchanger using the combustion heat of a burner, and in particular a forced combustion water heater in which combustion air is supplied by a blower. The present invention relates to a control device for a water heater.

[Prior art] In forced combustion water heaters, the heat output of the burner is increased in order to meet the demand for increased hot water supply capacity, such as raising the temperature of the hot water and increasing the amount of hot water. Combustion air is supplied by a blower. and,
The amount of hot water supplied and the amount of combustion are controlled according to the hot water supply state, so that the required temperature and amount of hot water can be obtained.

[Problem to be solved by the invention] However, in such forced combustion type water heaters, if the amount of hot water supplied exceeds the heating capacity, or if the temperature of the water flowing into the heat exchanger is low, the amount of combustion of the burner will decrease. Because the heat exchanger cannot keep up with the heat exchanger, the water passing through the heat exchanger cannot be sufficiently heated, and hot water may be supplied at a low outlet temperature. In such a case, a large amount of water vapor generated by combustion in the burner is cooled by low-temperature water passing through the heat exchanger, condenses, adheres to the heat exchanger, etc., and becomes drain. If drainage continues to occur, there are problems such as equipment being corroded by the generated drainage.

The present invention suppresses the generation of drain when the amount of hot water supplied exceeds the heating capacity, or when the temperature of the hot water that comes out of the heat exchanger decreases due to the low temperature of the water flowing into the heat exchanger. An object of the present invention is to provide a control device for a forced combustion water heater that can protect the water heater by discharging ungenerated condensate.

[Means for Solving the Problems] The present invention provides a solenoid valve provided in a fuel supply path to a burner, a blower for supplying combustion air to the burner, and an air flow from a heat exchanger heated by the burner. temperature detecting means for detecting the temperature of the water being heated; and a control means for closing the solenoid valve and continuously operating the blower when the temperature of the water detected by the temperature detecting means is below a predetermined temperature. Adopt technical measures consisting of.

For example, if the temperature of the water flowing into the heat exchanger is low, or if the amount of hot water heated by the burner is insufficient due to a large amount of hot water being supplied,
Since the heat exchanger is not heated enough, the temperature of the water leaving the heat exchanger decreases.

However, in the present invention, the temperature of the water flowing out from the heat exchanger is detected by the temperature detection means, and if the detected temperature is below a predetermined temperature, the solenoid valve installed in the fuel supply path to the burner is activated. Since the control means closes the burner, combustion of the burner stops.

At this time, the blower is continuously operated by the control means, so that only air is continuously supplied to the burner.

[Effects of the Invention] In the present invention, when the water passing through the heat exchanger cannot be sufficiently heated and the water vapor generated due to combustion in the burner is cooled by the heat exchanger and drain is generated, ,
Since combustion in the burner is stopped, no water vapor is generated, and even after combustion is stopped, only air is supplied, so the generated condensate is discharged. Therefore, since no drain remains in the equipment, corrosion of the equipment is reduced, and equipment such as heat exchangers and burners can be protected.

[Example] Next, the present invention will be explained based on embodiments shown in the drawings.

Figure 2 shows an outline of the gas water heater of this embodiment, and shows the combustor 1.
0, a fuel pipe 20, a water pipe 30, and a control device 40.

The combustor 10 is composed of a burner group 11 provided in the water heater case 1 and a combustion fan 12 that supplies combustion air, and the combustion fan 12 as a blower of the present invention supplies fuel gas supplied from a nozzle 13. All-primary air combustion is performed using only the primary air supplied by 12, and the combustion gas is discharged from the exhaust port 2. The burner group 11 is a double burner in which a plurality of metal ribbon burners are arranged in two rows, and on one side near the burner group 11 there is a sparker 14 of an ignition device and a frame for flame detection. A rod 15 and a thermocouple 16 are provided, respectively.

The fuel pipe 20 is a gas pipe that supplies fuel gas to the nozzle 13, and includes, in order from the upstream side, a main solenoid valve 21, a main solenoid valve 22, and a proportional valve 23 that adjusts the amount of fuel supplied to the burner group 11. The fuel pipes 20 are branched downstream of the proportional valve 23 to supply fuel gas to each of the two burners, and one of the branched fuel pipes 20 is connected to one of the burner groups 11. In order to burn only one series,
A switching valve 24 is provided.

The water pipe 30 includes a supply pipe 31 and a hot water supply pipe 31a connected to a water supply source and a hot water supply port (not shown), respectively, and a heat exchanger 32 and a bypass pipe 3 provided to communicate these.
2a, a part of the water supplied from the supply pipe 31 is led to the hot water supply pipe 31a via the heat exchanger 32, and the remaining part is led to the hot water supply pipe 31a via the bypass pipe 32a. A bypass valve 33 is provided at the downstream confluence section, and mixes the water heated by the heat exchanger 32 and the water directly guided through the bypass pipe 32a by appropriately adjusting the ratio thereof.

On the other hand, a water flow control valve 34, a water flow sensor 35, and an inlet water temperature thermistor 36 are installed in the supply pipe 31 from the upstream side, a heat exchange thermistor 37 is installed downstream of the heat exchanger 32, and an outlet water temperature thermistor 38 is installed in the hot water supply pipe 31a. The heat exchange thermistor 37 serves as the temperature detection means of the present invention.

The control device 40 is a control means of the present invention, and as shown in FIG. It consists of a microcomputer 42, a safety circuit 43 for ensuring safety, a solenoid valve energizing relay circuit 44, and a power supply section 45 that supplies power to all of these, and a controller for operating the gas water heater. 46, and a mode setting circuit 47 for presetting the operating mode of the microcomputer 42.

First, each circuit as the interface 41 will be explained.

The sparker circuit 51 includes a high voltage generation section that generates a high voltage for causing spark discharge to the sparker 14, and a discharge detection section that detects the spark discharge at the sparker 14.

The flame temperature detection circuit 52 is a circuit that amplifies the output voltage of the thermocouple 16 according to the temperature of the flame to be detected for use as a control signal, and the amplified signal is used to control the air-fuel ratio during combustion. .

The water temperature detection circuit 53 is a circuit for obtaining temperature signals from the resistance values of each thermistor arranged in the water pipe 30.
The temperature signal is obtained by dividing the power supply voltage by resistors connected in series with each thermistor.

The fan circuit 55 is a circuit for driving the combustion fan 12 based on the pulse signal transmitted from the microcomputer 42, and changes the output voltage according to the pulse width of the transmitted pulse signal to the control voltage of the fan drive circuit. Apply as. It also includes a rotation speed detection circuit that outputs a voltage according to the rotation speed of the combustion fan 12, and sends the rotation speed signal to the microcomputer 42.

The proportional valve port path 56 is a circuit that energizes the proportional valve 23 that adjusts the fuel gas. In this example, the current is 20
Since the Hz pulse signals are superimposed and the proportional valve 23 vibrates when energized, the hysteresis characteristic of the proportional valve 23 is eliminated, resulting in almost no hysteresis.

The water flow circuit 59 operates based on a pulse signal from the water flow sensor 35 that is generated according to the amount of water passing through the water pipe 30.
The pulse signal is transmitted to the microcomputer 42, and when the amount of Mercury passing through the water pipe 30 exceeds a certain level, a switching signal is sent to the relay circuit power supply 45b of the power supply section 45, and the water flow signal is transmitted to the safety circuit 43. Transmit.

The microcomputer 42 is a custom IC designed for the gas water heater of this embodiment and equipped with a storage device that stores programs and data necessary for its operation, and performs predetermined sequence control, a controller 46, and a water temperature detection circuit 5.
Combustion amount control and water amount control are performed based on each signal from No. 3 and five water flow circuits.

As part of this water flow control, the amount of water passing through the heat exchanger 32 and the amount of water passing through the bypass pipe 32a are controlled by the bypass valve 3.
3, the temperature of the water flowing out from the heat exchanger 32 is normally maintained at 60°C or higher even when the set water temperature is low, and the temperature of the water flowing out from the heat exchanger 32 is adjusted by the bypass valve 33 so that the water temperature reaches the set temperature. The amount ratio is adjusted. However, if the temperature of the water supplied from the supply pipe 31 is very low or if the opening of the water faucet operated by the user is large, the opening of the water flow control valve 34 may be controlled. Even if the temperature is adjusted by C, the temperature of the water flowing out from the heat exchanger 32 may not exceed 60'C. In such a case, water vapor generated during combustion in the burner group 11 is condensed by low-temperature water and becomes drain.

In order to prevent the burner group 11, heat exchanger 32, etc. from being corroded by such drainage, in this embodiment, the water temperature detected by the heat exchange thermistor 37 is lower than 55 degrees Celsius, and the water temperature is lowered for 5 minutes. If it continues, burner group 1
In order to stop the combustion of the fuel, both the original solenoid valve 21 and the main solenoid valve 22 are closed, and the combustion fan 12 is continuously operated to discharge the generated condensate.

Then, the user is informed of the combustion stoppage by a pre-designated display, and is prompted to reduce the amount of hot water supply or restart the operation.

The safety circuit 43 detects an abnormality in any one of the flame detection signal from the flame detection circuit 8, the water flow signal from the water flow circuit 59, and the pulse signal constantly sent out during the operation of the microcomputer 42. This circuit sometimes sends out a switching signal to stop the power supply to the microcomputer 42 and the electromagnetic valve energizing relay circuit 44.

Note that the safety circuit 43 is equipped with a reset circuit with a timer that stops the operation of the safety circuit 43 using a control signal for closing the original solenoid valve 21 and the main solenoid valve 22. , the safety circuit 43 is activated only after combustion in the combustor 10 has started.

The solenoid valve energizing relay circuit 44 is a circuit consisting of a relay for respectively energizing the original solenoid valve 21, the main solenoid valve 22, and the switching valve 24 in accordance with a control signal from the microcomputer 42.

When a plug (not shown) is inserted into an outlet, the power supply unit 45 converts the electric power for operating the above-mentioned circuits of the control device 40 into the voltage necessary for each circuit and constantly supplies the voltage. Now, microcomputer 42
a microcomputer power supply 45a that supplies power to the microcomputer, and a relay circuit power supply 45 that supplies power to the solenoid valve energizing relay circuit 44.
b has a switching function that stops the power supply in response to the energization stop signal from the safety circuit 43, which stops the operation of the microcomputer 42 and stops the energization to each electromagnetic valve, thereby stopping the fuel supply.

In addition, the relay circuit power supply 45b that supplies power to the solenoid valve energizing relay circuit 44 can energize each solenoid valve only when a switching signal from the water flow circuit 59 is transmitted, and the water flow is detected. If not, fuel gas is not supplied to the burner group 11, so there is no need to worry about dry firing.

The power supply section 45 is provided with a temperature fuse (not shown), an over-twitch, and a boiling prevention switch (not shown) in an electric line connected to a commercial power source to further ensure safety.

The controller 46 is for setting and operating the operating state of the gas water heater, and includes a small-capacity microcomputer operated by power from a communication circuit 57 and a communication circuit in order to exchange signals with the microcomputer 42. , modulates the setting signal and sends it to the microcomputer 42. The controller 46 also has a display function, which displays the set hot water temperature using digital numbers on a liquid crystal display, and also indicates when the combustor 10 is burning by a lamp.

The gas water heater of this embodiment having the above configuration operates as follows.

When the user turns on the operation switch using the controller 46, sets the hot water temperature, and operates a faucet (not shown), the combustion fan 12 starts rotating, and
The filtrate supplied by the supply pipe 31 is supplied through a water flow control valve 34,
The water passes through the water flow sensor 35, flows into the heat exchanger 32 and the bypass pipe 32a, the outflow amount of which is adjusted by the bypass valve 33, and flows out from the hot water supply port (not shown) via the hot water supply pipe 31a. Then, a water flow signal and a pulse signal corresponding to the water flow transmitted from the water flow sensor 35 via the water flow circuit 59 are transmitted to the electromagnetic valve energization relay circuit 44 and the microcomputer 42.

Then, in the solenoid valve energizing relay circuit 44, each solenoid valve becomes energized in accordance with the control signal from the microcomputer 42. On the other hand, when the microcomputer 42 detects a predetermined number or more of transmitted pulse signals, Combustor 10
As the ignition operation, the high voltage generating part of the sparker circuit 51 is energized to discharge a spark to the sparker 14.
Since the control signals of the original solenoid valve 21 and the main solenoid valve 22 sent to are signals that close each solenoid valve, the safety circuit 43 does not operate, and the control signal from the microcomputer power supply 45a to the microcomputer 42 is a signal that closes each solenoid valve. Electricity is supplied.

When the spark discharge in the sparker 14 is detected by the operation detection section of the sparker circuit 51, the microcomputer 42 changes the control signal for the original solenoid valve 21 and the main solenoid valve 22, which had been the signal for closing the valve, to open. Change the signal to the state and send it. At this time, the safety circuit 43 does not operate for a certain period of time even after the control signal of each solenoid valve becomes an open signal due to the circuit to the timer reset 1, so the microcomputer 42 continues to receive power. Supplied.

Therefore, the original solenoid valve 21 and the main solenoid valve 22 are energized by the solenoid valve energizing relay circuit 44, and the fuel gas is supplied to the nozzle 13.
The fuel is ejected from the air, mixed with combustion air, and supplied to the burner group 11, where it is ignited by the sparker 14, which is already in operation.

When ignition is detected by the flame rod 15 and a flame detection signal is sent from the flame detection circuit 58, the inlet water temperature thermistor 36, the heat exchange thermistor 37, and the outlet water temperature thermistor 38
The required combustion amount is calculated based on the detection signals from each thermistor and water flow sensor 35 and the setting signal from the controller 46, and based on the calculation results, the combustion fan 12, proportional valve 23, switching valve 24, bypass valve 33 and water flow control valve 34 are controlled. Further, after ignition, air-fuel ratio correction control is also performed based on the signal from the thermocouple 16, but this control is not performed for a certain period of time until the temperature of the thermocouple 16 stabilizes.

Thereafter, if there is a change in the amount of hot water or the set temperature, the ratio of the flow rate passing between the heat exchanger 32 and the bypass pipe 32a and the combustion amount by the bypass valve 33 are changed in accordance with the change.

At this time, if the water temperature detected by the outlet hot water temperature thermistor 38 of the hot water supply pipe 31a is lower than the water temperature set by the controller 46, the amount of water passing through the heat exchanger 32 and the amount of water passing through the bypass pipe 32a are bypassed. It is regulated by valve 33.

However, if the temperature of the water flowing out of the heat exchanger 32 does not rise for some reason and becomes below 55°C, the water vapor generated during combustion is cooled by the low-temperature water passing through the heat exchanger 32 and condenses. and becomes a drain. Then, at this time, the microcomputer 42 starts operating based on the detection signal from the heat exchange thermistor 37 inputted via the water temperature detection circuit 53, and when the state of 55°C or less continues for 5 minutes, it closes each solenoid valve. In the closed state, burner group 11
The fuel supply to the engine is stopped, thereby stopping combustion.

Therefore, thereafter, no drain is generated due to combustion.

Further, at this time, the combustion fan 12 is continuously operated to supply air into the water heater case 1, so that the generated drain is discharged from the water heater case 1 by the supplied air.

When the user senses that combustion has stopped on the display section of the controller 46, the user can resume hot water supply by decreasing the opening degree of the faucet or restarting the faucet.

As described above, according to the combustion type water heater control device of the present invention, when the heat exchanger is not sufficiently heated and drainage occurs, combustion of the burner is stopped and only the blower is operated. Therefore, the generation of condensate can be reduced and the generated condensate can be discharged, so that combustion equipment can be protected and corrosion is less likely to occur.

In this embodiment, the original solenoid valve and the main solenoid valve are provided twice as solenoid valves, but the number is not necessarily limited.

Further, in this embodiment, a gas water heater is shown that is equipped with a bypass pipe that leads the hot water to the hot water supply port without passing through a heat exchanger, but the same effect can be obtained in a water heater that does not have a bypass pipe.

Furthermore, although the effect is great when using gas as fuel, it can also be used with fuels such as petroleum.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control device for a gas water heater according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the configuration of the gas water heater according to the embodiment. In the figure, 12... Combustion fan (air blower), 21...
Original solenoid valve (solenoid valve), 22...main solenoid valve (solenoid valve),
37...Heat exchange thermistor (temperature detection means), 4°.
...Control bag M, (control means).

Claims (1)

[Claims] 1) A solenoid valve provided in a fuel supply path to a burner, a blower that supplies combustion air to the burner, and a flow of water flowing out from a heat exchanger heated by the burner. Comprised of a temperature detection means for detecting temperature, and a control means for closing the solenoid valve and continuously operating the blower when the temperature of the water detected by the temperature detection means is below a predetermined temperature. Control device for forced combustion water heaters.