JPH102608A - Hot-water supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot-water supply apparatus wherein the combustion amount of a burner does not exceed the maximum combustion amount even when there is an unevenness in a supply gas. SOLUTION: During a hot water discharging motion, a controller calculates (S4) the calory being utilized for the heating of water by the difference between a supply hot water temperature and a fed cold water temperature, and the sum of a fed cold water flow rate, and compares the calculated value and a previously stored reference value (S5). When the calculated value exceeds the reference value (S5:YES), it is judged that the combustion amount of a burner has exceeded the maximum combustion amount by a reason such as the Wobbe index of a gas to be fed is large, or the content of butane is high, and the opening degree of a proportional valve is adjusted in the closing direction to reduce the amount of the feeding gas (S6), and the combustion amount of the burner is reduced, and when the calculated value becomes the reference value or less, the adjustment is completed (S5:NO).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater for controlling a hot water temperature by adjusting a combustion amount of a burner.

[0002]

2. Description of the Related Art Conventionally, there has been known a water heater which supplies supplied water by heating the supplied water by the combustion heat of a burner. Generally, such a water heater is provided with a proportional valve for adjusting a gas supply amount to a burner, and performs a hot water temperature control for adjusting a combustion amount of the burner to make a hot water temperature close to a set temperature. In addition, the maximum burning amount of the burner is determined in consideration of the durability of the appliance and the burnability of the burner, and the maximum burning amount determines the maximum capacity of the appliance. For example, if there is a capacity to discharge 16 liters of hot water at a temperature rise of 25 ° C. per minute,
The ability is classified as No. 16. The maximum combustion amount of the burner is limited by the maximum opening of the proportional valve.

[0003]

However, even if the opening of the proportional valve is the same, the burner combustion amount may be different. For example, in city gas, the Wobbe index (the value obtained by dividing the calorific value of gas by the square root of the specific gravity of gas) varies, and if the Wobbe index is large even if the proportional valve opening is the same, a burner is generated in proportion to it. The amount of heat increases.
Similarly, the butane content of the LP gas varies, and the higher the butane content, the greater the amount of heat generated by the burner. Further, even when the Wobbe index is low, the governor characteristics may jump due to an increase in pressure loss in the gas passage, and the calorific value of the burner may increase. As a result, the capacity was exceeded (the amount of heat required to raise the temperature of the water to the set temperature exceeded the maximum amount of heat generated by the burner)
In such a state, the proportional valve opening is at its maximum.Therefore, when the Wobbe index is large, the burner combustion amount exceeds the maximum combustion amount, and the combustion state and durability deteriorate. Was. Therefore, in practice, it is necessary to provide a margin in flammability and durability. For example, the maximum capacity has to be used as No. 16 even though the equipment can be used with No. 18 maximum capacity.

An object of the present invention is to provide a water heater in which the above-mentioned problems are solved, and the burner combustion amount does not exceed the maximum combustion amount even when the supply gas varies.

[0005]

A water heater according to the present invention for solving the above-mentioned problems comprises a heat exchanger which heats water supplied from a water supply passage by combustion heat of a burner and supplies the water to a tap water passage. A flow rate sensor for detecting a flow rate flowing through the boiler, an incoming water temperature detecting means for detecting a temperature of supplied water, a hot water temperature sensor for detecting a temperature of hot water in the hot water path, and adjusting a combustion amount of the burner. In the water heater provided with the combustion amount adjusting means, the heating amount calculated based on the detected value of the flow rate sensor, the detected value of the incoming water temperature detecting means, and the detected value of the outlet water temperature sensor is a predetermined value. If it exceeds, the gist of the invention is to adjust the burner combustion amount so that the heating amount becomes equal to or less than the predetermined value.

[0006] The water heater of the present invention having the above-described structure heats the water supplied from the water supply channel by the combustion heat of the burner and discharges the water. Here, even when the burner combustion amount exceeds the maximum combustion amount specified for the appliance, the calorie used for water heating is calculated from the incoming water flow rate, the incoming water temperature, and the outlet water temperature, and the calculated value is determined to be a predetermined value. If the value exceeds the value, the burner burn rate is judged to exceed the maximum burn rate and the burn rate is adjusted.
It can be limited to the maximum combustion amount or less. In addition to the method of directly detecting the temperature by providing a temperature sensor in the water supply path, the detection of the incoming water temperature may be calculated back from the outgoing water temperature, the incoming water flow rate, and the combustion amount of the burner. It may be assumed from the detection value of the temperature sensor.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the water heater of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a water heater as one embodiment of the present invention. The water heater includes a heat exchanger 3 to which a water supply passage 1 and a tapping water passage 2 are connected, a burner 4 for heating water flowing through the heat exchanger 3, and a gas supply passage 5 for supplying gas to the burner 4. And a controller 6 for controlling combustion. The water supply path 1 is provided with a water governor 7 for adjusting the maximum flow rate according to the incoming water temperature, a flow rate sensor 8 for detecting the incoming water flow rate, and an incoming water temperature sensor 9 for detecting the incoming water temperature. Is provided with a tap water temperature sensor 10 for detecting a tap water temperature, and a hot water tap 11 is connected downstream thereof. The gas supply path 5 is provided with a main solenoid valve 12 for opening and closing the flow path, a main solenoid valve 13, and a proportional valve 14 for adjusting the gas amount.

The controller 6 includes a CPU, a RAM, and a ROM constituting a well-known arithmetic and logic operation circuit (not shown), an input interface for inputting signals from various sensors, and
It is composed of an output interface that outputs drive signals to various actuators. Further, the controller 6 is connected to a remote controller 15 including an operation switch for setting a set temperature.

The controller 6 calculates and controls the amount of gas required to bring the hot water temperature to the set temperature on the basis of the set temperature, the incoming water temperature, and the incoming water flow rate. And the feedback control (hereinafter, referred to as FB control) for correcting the FF control amount based on the difference between the tapping temperature and the set temperature, thereby adjusting the opening of the proportional valve to perform the tapping temperature control.

Next, control processing performed by the controller 6 will be described with reference to the flowchart of FIG. The hot water tap 11 is opened to start water flow to the appliance, and the flow sensor 8
(S1: YE)
S), the main solenoid valve 12 and the main solenoid valve 13 are opened to supply gas to the burner 4 and ignited by an ignition device (not shown) (S2) to start a combustion operation. FF control based on the product of the difference between the set temperature set by the remote controller 15 and the detected temperature of the incoming water temperature sensor 9 and the flow rate detected by the flow rate sensor 8; The tapping temperature control is performed by adjusting the opening of the proportional valve 14 by the FB control based on the deviation of the hot water (S3).

[0011] During the tapping operation, to determine whether or not the burned amount of the burner 4 exceeds the maximum burned amount, the water heating is determined from the product of the difference between the tapped water temperature and the incoming water temperature (rising temperature) and the incoming water flow rate. Is calculated (S4). Further, the controller 6 stores the product of the heat generation amount and the thermal efficiency at the predetermined maximum combustion amount of the burner 4 as a reference value, and compares the reference value with the calculated value to thereby determine the combustion of the burner 4. The amount is checked (S5). Here, if the calculated value is equal to or less than the reference value (S5: NO), it is determined that the combustion amount of the burner 4 is equal to or less than the maximum combustion amount. However, if the calculated value exceeds the reference value (S5: YES), it is determined that the burned amount of the burner 4 has exceeded the maximum burned amount because the Wobbe index of the supplied gas is large. Then, the proportional valve opening is adjusted in the closing direction to reduce the supply gas amount (S
6) The combustion amount of the burner 4 is reduced, and the adjustment is terminated when the calculated value becomes equal to or less than the reference value (S5: NO).

FIG. 3 shows a tapping capacity diagram when the inlet water temperature of this water heater is 15 ° C. In this water heater, the maximum flow rate is 8.9 liters / hour when the incoming water temperature is 15 ° C. by the water governor 7 so that hot water at 60 ° C. can be secured regardless of the incoming water flow rate.
Limited to minutes. Therefore, when the set temperature is set to 75 ° C. and the hot water tap 11 is fully opened, the burner 4
Although the amount of combustion becomes maximum, the tapping temperature rises only up to 60 ° C. Here, when the combustion amount of the burner 4 is increased by 10% due to a situation such as a large Wobbe index or a high butane content, as shown at a point b, the tapping temperature rises to 64.4 ° C. , And the combustion continues at a combustion amount of 10% UP of the maximum combustion amount, so that the burnability of the burner 4, the durability of the equipment, and the like deteriorate.
However, in the water heater of the present embodiment, the calorie used for heating the water is calculated from the incoming water temperature, the outgoing water temperature, and the incoming water flow rate, and when it is determined that the combustion amount of the burner 4 exceeds the maximum combustion amount, In order to reduce the amount of combustion, the amount of combustion of the burner 4 can be limited to the maximum amount of combustion or less.

As described above, according to the water heater of the present embodiment, even if the burned amount of the burner 4 exceeds the maximum burned amount for some reason, the difference between the outlet water temperature and the incoming water temperature can be improved. The amount of heat used for water heating is calculated from the product of the product and the flow rate of incoming water, and the amount of combustion of the burner 4 is checked by comparing with the reference value.
If the calculated value exceeds the reference value, the amount of gas supply is reduced to limit the amount of combustion of the burner 4 to the maximum amount of combustion or less. It is not necessary to improve the durability and the burnability of the burner excessively. Further, by calculating the amount of combustion of the burner 4 using a sensor conventionally used for hot water temperature control, it is not necessary to use a new sensor, so that the cost can be reduced.

In this embodiment, the incoming water temperature is detected by the incoming water temperature sensor 9. However, without providing the incoming water temperature sensor 9, the outgoing water temperature, the incoming water flow rate, and the proportional valve opening may be calculated back.
Also, the incoming water temperature may be assumed from the detected temperature of the hot water temperature sensor 10 or the temperature change at the start of hot water supply. Further, in the present embodiment, the calorie used for heating the water calculated from the incoming water temperature, the outgoing water temperature, and the incoming water flow rate is compared with a reference value which is a product of the amount of heat generated at the maximum combustion amount of the burner 4 and the thermal efficiency. However, the amount of heat generated by the burner 4 may be calculated by dividing the amount of heat calculated from the incoming water temperature, the outlet water temperature, and the incoming water flow rate by the thermal efficiency, and the generated heat amount at the maximum combustion amount may be compared as a reference value.

The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

[0016]

As described in detail above, according to the water heater of the present invention, the burner burn amount can be limited to the maximum burn amount specified for the appliance or less, and the burnability and durability deteriorate. Can be prevented, and it is not necessary to excessively improve the durability of the apparatus and the burnability of the burner. Also, by calculating the amount of heat used for heating water using a sensor conventionally used for hot water temperature control, it is not necessary to newly provide a sensor or the like, so that costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a water heater as one embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control process performed by a controller.

FIG. 3 is a graph showing a tapping capacity range.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Water supply channel, 2 ... Hot water supply channel, 3 ... Heat exchanger, 4 ... Burner, 6 ... Controller, 8 ... Flow rate sensor, 9 ... Input water temperature sensor, 10 ... Hot water temperature sensor, 11 ... Hot water tap, 14 ... Proportional valve , 15 ... Remote control.

Claims (1)

[Claims] 1. A heat exchanger for heating water supplied from a water supply passage by combustion heat of a burner and supplying the water to a hot water passage, a flow sensor for detecting a flow amount flowing through the heat exchanger, and a supplied water. A water inlet temperature detecting means for detecting a temperature, a hot water temperature sensor for detecting a temperature of hot water in the hot water path, and a combustion amount adjusting means for adjusting a combustion amount of the burner; If the heating amount calculated based on the detection value, the detection value of the incoming water temperature detection means, and the detection value of the tap water temperature sensor exceeds a predetermined value, the heating amount becomes equal to or less than the predetermined value. A water heater characterized in that the burner combustion amount is adjusted as described above.