JP2001059647A - Empty firing detector for hot water supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect empty firing surely using an inexpensive thermostat without causing any burn up in the frame. SOLUTION: The empty firing detector comprises an empty firing detection thermo 8 for detecting surface temperature of a vessel and opening at a specified temperature or above, a first timer 15 starting combustion and counting upon turning a power switch 12 on and stopping combustion upon expiration of a specified time, and a second timer 16 starting counting upon time up of the first timer 15 and resuming combustion upon expiration of a specified time. Since empty firing is detected by the empty firing detection thermo 8 during operation of the second timer 16, empty firing is detected surely through an inexpensive thermo without causing any burn up in the frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting an empty boiler of a hot water heater of a hot water storage type using a thermostat.

[0002]

2. Description of the Related Art Conventionally, in this type of apparatus, a pair of empty heating detection electrodes utilizing conduction of hot and cold water is provided in a can, and it is detected whether or not the inside of the can is empty based on the presence or absence of conduction. In such cases, combustion was prevented to ensure the safety of the equipment.

[0003]

However, in this conventional device, the empty-fire detection electrode itself is extremely expensive and causes a cost increase. In addition, if the impurities such as calcium easily adhere to the electrode, the empty-fire detection can be performed. However, there was a problem of malfunction.

[0004]

In order to solve the above-mentioned drawbacks, the present invention focuses on this point. In particular, the present invention comprises a hot water storage can and a burner for heating hot water in the can. An empty-fire detection thermostat that detects the surface temperature of the can body and opens a normally closed contact at a predetermined temperature or higher to detect empty-fire, and starts burning and counting by turning on the power switch, and time-up after a predetermined time A first timer for stopping the combustion, and a second timer for starting counting when the first timer expires and restarting the combustion after a predetermined time.
A timer is provided, and during the operation of the second timer, the empty-fire detection is performed by the empty-fire detection thermostat.

[0005]

When the power switch 12 is turned on, combustion of the burner section 7 is started, and the combustion time is counted by a first timer 15, and this combustion is stopped once after a predetermined time. Let it.

When the first timer 15 times out, the second timer 16 starts counting. At this time, the surface of the can 1 rises in temperature due to the subsequent combustion. Most of the heat is absorbed by the hot water in the can 1 and the surface temperature of the can 1 does not rise.
When there is no hot water in the container and the container is empty, most of the heat is directly transmitted to the surface of the can 1, so that the empty heating detection thermo 8 is activated before the second timer 16 times out, and the second timer 16 In addition to preventing the start of combustion after the time-up, the display unit 14 indicates that the unit is in an idle-fired state.

[0007] Therefore, since the empty heating is detected by the thermostat for detecting the surface temperature of the can 1, the cost is extremely low and the cost is reduced. In addition, since the temperature rise after the combustion is stopped once is detected, the temperature rises rapidly. By such a temperature rise, it is possible to reliably prevent burning of the plastic parts in the frame body 24 in particular.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a cylindrical can body for storing a certain amount of hot water, and has a bath heat exchanger 2 inside.
A combustion chamber 4 is provided below the smoke tube 3 and below. The combustion chamber 4 is further provided with a gun-type burner unit 7 in which an ignition electrode 5 and a nozzle 6 are integrated.

Reference numeral 8 denotes an empty-fire detection thermostat provided on the top of the can body 1 and comprising a thermostat for detecting the surface temperature of the can body 1. The thermostat is normally closed and is opened when it detects a predetermined temperature or higher and 95 ° C. or higher, here. When the temperature drops to 70 ° C., the closed state is automatically returned to the closed state.
The change is detected by the change in the surface temperature.

Reference numeral 9 denotes a hot water temperature thermistor for detecting the hot water temperature in the can 1, comparing the set temperature with the current hot water temperature to ON-OFF and proportionally control the combustion of the burner unit 7 to set the hot water temperature. The temperature is detected, and at the time of starting the operation, it is detected that the fuel cell is in a non-idling state.

Reference numeral 10 denotes a microcomputer provided on a printed circuit board 11 for controlling each section. The input side is connected to a power switch 12 for starting operation of the apparatus, an empty heating detection thermostat 8 and a hot water temperature thermistor 9, and an output side. A drive circuit 13 for driving the burner unit 7 and each unit, and a display unit 14 for displaying an operation state, a set temperature, a time, an error state at the time of abnormality, etc.
Are connected to control the entire apparatus.

Reference numeral 15 denotes a first timer which is built in the microcomputer 10 as a function. The first timer 15 controls the drive circuit 13 by turning on a power switch 12 to start the combustion of the burner unit 7 and to start counting for a predetermined time. Subsequent time-up Here, the combustion is stopped after 70 seconds.

Reference numeral 16 denotes a second timer provided in the microcomputer 10 similarly to the first timer 15. The second timer 16 starts counting when the first timer 15 times out, and burns after a predetermined time, here 60 seconds after. When the surface temperature of the can 1 rises to the operating temperature of the empty-fire detection thermometer 8 during the operation of the second timer 16, the empty-fire detection thermometer 8 is restarted. It is opened to prevent combustion after the time-up of the second timer 16 via the microcomputer 10 and to cause the display unit 14 to display an abnormal state of idle heating.

Reference numeral 17 denotes a water supply pipe which supplies water from the city water supply to the can body 1 under reduced pressure, and is provided side by side with a hot water supply pipe 18 for supplying the hot water heated by the can body 1 to a required hot water supply point. .

A circulation circuit 19 communicates the bath heat exchanger 2 in the can body 1 with the bathtub 20, and a circulation pump 21
Further, a bath thermistor 22 for detecting the temperature of hot water in the bathtub 20 is provided, and the burner unit 7 and the circulation pump 21 are controlled by the bath thermistor 22 to perform boiling and reheating of the bath.

Reference numeral 23 denotes an exhaust pipe projecting from the upper surface of a frame 24 constituting a water heater which communicates with the smoke pipe 3 and accommodates the whole water heater. A silencer section 25 for reducing noise during exhaust is provided in the middle.

Reference numeral 26 denotes a main remote controller for remotely controlling the water heater, which includes a power switch 12, various switches (not shown) for setting a set temperature and a timer time, and a display unit 14, together with a bathroom remote controller 27. Things. 2
Reference numeral 8 denotes a power plug for supplying power to each unit.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. Now main remote control 2
If one of the power switches 12 provided on both the remote controller 6 and the bathroom remote controller 27 is turned on (step 29),
The burner unit 7 starts combustion (step 30), and in step 31, the first timer 15 counts this combustion for 70 seconds, and proceeds to step 32 to temporarily stop the combustion.

Next, the program proceeds to step 33, where the temperature of the hot water in the can 1 is detected by the hot water thermistor 9, and if the state is not the idle heating, the temperature of the hot water in the can 1 drops by 1 ° C. or more for 5 seconds after stopping the combustion. Therefore, if this is detected by the hot water temperature thermistor 9, the process proceeds to step 34 with YES to return to the normal control for controlling the hot water temperature to the set temperature. This is the value obtained, whereby the control can be immediately returned to the normal control without waiting for the second timer 16 to count up.

If the temperature of the hot water has not dropped in step 33, the determination is NO, and the process proceeds to step 35 to determine whether or not the surface temperature of the can 1 reaches the operating temperature of the empty-fire detection thermostat 8. In step 36, counting is started from the time-up of the first timer 15 and 60
The operation is performed until the second timer 16 that counts the second is up. When the inside of the can 1 is in an empty fire state, the operating temperature of the empty fire detection thermo 8 reaches 95 ° C. within the 60-second extinguishing time.
The ES proceeds to step 37 to prevent re-ignition, that is, to proceed to the normal control.
Is displayed to indicate that there is an abnormality in the empty firing state.

When the state is not the empty firing state, the heat generated by the combustion is absorbed by the hot and cold water in the can 1, so that the surface temperature of the can 1 does not rise to the operating temperature of the empty heating detection thermometer 8.
When the second timer 16 expires, the process proceeds to step 39 of the normal control including re-ignition.

Therefore, it is possible to surely detect the empty firing using an inexpensive thermostat, which is extremely convenient and has an advantage in cost.

Further, as shown in the characteristic diagram of the surface temperature of the can body shown in FIG. 5, in the continuous combustion state, the operating temperature of the empty-fire detection thermostat 8 is instantaneously reached, but the temperature rises rapidly and the temperature rises even when the fire extinguishing operation is performed. It does not stop and leads to burning of the plastic parts in the frame 24. However, as in the present invention, the first and second timers 1 are used.
By having a fire extinguishing time of 60 seconds after the burning of 70 seconds by 5 and 16, the rapid temperature rise is suppressed, the burning of the plastic parts in the frame 24 is prevented, and the empty firing is reliably detected in a short time. It is extremely convenient and can be used with confidence.

Further, when the heating state is not the idle state, the hot water temperature thermistor 9 detects the hot water temperature, so that the control can be promptly shifted to the normal control without waiting for the time-up of the second timer 16, thereby shortening the time. You can do it.

In this embodiment, the power switch 12
N always performs the empty-fire detection operation. However, in the case of this type of hot-water storage type water heater, the danger of empty-fire is limited after forgetting to connect pipes at the first use or after long-term non-use. Alternatively, it may be limited to the first use only when the power plug 28 is inserted into the outlet.

[0026]

As described above, according to the present invention, it is possible to reliably detect an empty-fire detection using an inexpensive empty-fire detection thermometer without using expensive electrodes, which is extremely convenient and The cost can be reduced, and the plastic parts in the frame can be reliably prevented from burning.

[Brief description of the drawings]

FIG. 1 is a side view of a water heater to which an embodiment of the present invention is attached, with a side plate removed.

FIG. 2 is a schematic configuration diagram of the same.

FIG. 3 is a block diagram of the main part electric circuit.

FIG. 4 is a flowchart of the main part.

FIG. 5 is a characteristic diagram of the can body surface temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Can body 7 Burner part 8 Dry firing detection thermometer 12 Power switch 15 1st timer 16 2nd timer

Claims (1)

[Claims] 1. A hot-water storage type can body and a burner section for heating hot water in the can body, and further detects the surface temperature of the can body and opens a normally closed contact at a predetermined temperature or higher to detect empty heating. An empty heating detection thermostat, a first timer for starting combustion and counting by turning on a power switch and stopping this combustion after a predetermined time, and a predetermined time for starting counting when the first timer expires. A second timer for restarting combustion at a later time-up.
An empty-fire detection device for a water heater, wherein empty-heating detection is performed by the empty-heating detection thermo while the timer is operating.