JPH11257743A - Gas hot water supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an automatic transition to heat insulating operation when the operating frequency is high even if interruption of heat insulating operation is designated by a heat insulating switch. SOLUTION: A heat exchanger 13 is disposed on the channel between a water supply port 11 and a hot water delivery port 12 and water in the heat exchanger 13 is heated by means of a gas burner 21. If heat insulating operation is designated by a heat insulation switch 25 when water is not flowing through the channel, temperature sensors 32-34 detect the temperature of retaining water and when it drops below a reheating temperature, a heat insulation control section 30a fires the gas burner 21 for a specified time to raise the temperature of retaining water. If heat insulating operation is not designated by the heat insulation switch 25, the number of operating times per unit time is determined as operation frequency from the fluctuation of flow rate detected by a flow sensor 31. When the operation frequency exceeds a threshold level, a transition is made automatically to heat insulating operation which is sustained until a specified times elapses after interruption of hot water delivery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a gas water heater.

[0002]

2. Description of the Related Art In general, a gas water heater used for applications in which hot water comes into contact with a hand immediately after a hot water tap is opened, such as dishwashing, a washing surface, or a shower, does not cause a feeling of cold water to a person immediately after the hot water supply is started. Is desired. In order to satisfy this type of demand, a technique has been proposed for keeping the water held in the gas water heater (hereinafter referred to as "held water") warm when the hot water is not being supplied. This is so that the temperature of the water retained in the gas water heater is maintained at a predetermined temperature or higher even when hot water is not being supplied.
When the temperature of the retained water drops to the reheating temperature, the gas burner is ignited to keep the temperature. By performing such a heat retaining operation, the temperature of the water retained in the gas water heater can be kept relatively high, so that the temperature of the hot water discharged from the hot water tap after starting the hot water supply from the hot water tap reaches the set temperature. The time to reach can be relatively short.

[0003]

Incidentally, whether or not to perform the above-mentioned heat retaining operation is manually instructed by a heat retaining switch provided in the gas water heater. Therefore, the warming operation is not performed unless the warming switch is instructed by the warming switch. When the instruction for the heat-retention operation is given by the heat-retention switch, the heat-retention switch may be set to always instruct the stop of the heat-retention operation in order to suppress the consumption of the fuel gas. Here, in a usage mode in which hot water is repeatedly turned on and off in a relatively short time, such as in dishwashing or showering, it is better to perform a warming operation, and at the same time, the temperature of the hot water rises in a short time so that low-temperature water is discharged. There is also an advantage that the amount of water used can be reduced because it is not wasted. However, if the stop of the warming operation is instructed by the warming switch, such an advantage cannot be utilized, and the function of the warming operation cannot be fully utilized.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a purpose thereof is to automatically perform a heat-retaining operation when it is desired to perform a heat-retaining operation even when a stop of the heat-retaining operation is instructed by a heat-retaining switch. It is to provide a gas water heater in which the water supply is performed.

[0005]

SUMMARY OF THE INVENTION The present invention provides a heat exchanger provided on a flow path formed between a water inlet through which water flows in and a hot water outlet through which water is discharged, and water in the heat exchanger. A gas burner to be heated, a flow sensor for detecting the flow of water into the flow path, and an ignition control means for igniting the gas burner when the flow rate detected by the flow sensor is equal to or more than a predetermined value and extinguishing the gas burner when the flow rate is less than the predetermined value. A heat retention control means for intermittently igniting a gas burner after the flow rate detected by the flow rate sensor has shifted from a state of a predetermined value or more to a state of less than a predetermined value to keep the water held in the flow path, Insulation switch for instructing operation / stop of the insulation control means, frequency detection means for determining the number of uses per unit time as the usage frequency from a change in the flow rate detected by the flow sensor, and insulation for the insulation by the insulation switch In which the use frequency determined by the frequency detecting means to operate the and heat retention control means becomes equal to or higher than the threshold a predetermined time when the stop of the control means is instructed. According to this configuration, if the operation of the heat retention control means is instructed by the heat retention switch, the gas burner is intermittently ignited to keep the water held in the flow path warm. Even under low conditions, the feeling of cold water immediately after the start of hot water supply can be prevented. Also, even when the stop of the heat retention control means is instructed by the heat retention switch, when the hot water is frequently taken out and stopped in a short time, such as when used for washing dishes, even if the hot water is temporarily stopped, the comparison can be performed. By presuming that the hot water will be reused within a short period of time and operating the heat retention control means to keep the temperature warm, the user can be comfortably used without causing a feeling of cold water.

[0006]

FIG. 1 shows a schematic configuration of a gas water heater. As shown in FIG. 1A, the gas water heater shown as the present embodiment includes a water supply port 11 into which water flows in from outside and a water supply port 12 for discharging water.
A heat exchanger 13 is provided on the flow path between the heat exchanger 13 and the heat exchanger 13. The heat exchanger 13 is housed in the hot water supply combustion chamber 41 together with the gas burner 21, and water passing through the heat exchanger 13 is heated by the gas burner 21. A flow sensor 31 is provided on a flow path from the water supply port 11 to the heat exchanger 13, and the flow sensor 31 detects whether water is flowing through the flow path. The temperature of the water flowing from the water supply port 11 and passing through the flow rate sensor 31 is detected by the temperature sensor 32. A temperature sensor 34 that is heated by the heat exchanger 13 and detects the temperature of hot water discharged from the hot water outlet 12 is disposed near the hot water outlet 12,
Further, a temperature sensor 33 for detecting the temperature of the hot water discharged from the heat exchanger 13 is provided. A flow control valve 35 is provided on the flow path between the heat exchanger 13 and the tap 12 and near the tap 12. A gas burner 21 is connected to a gas connection port 22 through an original gas valve 23 which is an electromagnetic valve.
And fuel gas is supplied through the gas proportional valve 24.

Incidentally, the original gas valve 23 and the gas proportional valve 2
4. The flow sensor 31, the temperature sensors 32 to 34, and the flow control valve 35 are connected to a control circuit 30 including a microcomputer as shown in FIG. The control circuit 30 is based on the inputs from the flow sensor 31 and the temperature sensors 32-34.
According to the procedure shown in FIG. 2, the source gas valve 23, the gas proportional valve 24, and the flow control valve 35 are controlled. The control circuit 30 is connected to a heat retention switch 25, which instructs operation / stop of a heat retention control unit 30a, which will be described later.

More specifically, when a hot water tap (not shown) connected through the tap hole 12 is opened and the flow sensor 31 detects that water is flowing in the flow path (S1), the original gas valve 23 and the gas proportional The valve 24 is opened to ignite the gas burner 21 (S2). Although the ignition means of the gas burner 21 is not shown, a means for continuously generating and igniting a spark is used. When the ignition of the gas burner 21 is detected by a flame sensor (not shown), the spark is stopped. Is used. This type of ignition means is well known. After the ignition of the gas burner 21, the tapping temperature is adjusted by using the gas proportional valve 24 and the flow control valve 35 so that the tapping temperature detected by the temperature sensor 33 becomes a preset temperature (S3, S4).

On the other hand, when water flow in the flow path is no longer detected by the flow sensor 31 (S1), the original gas valve 23 and the gas proportional valve 24 are closed, and the gas burner 21 is extinguished (S5). When the gas burner 21 extinguishes, the temperature of the retained water in the flow passage drops significantly in winter. When water is not detected in the flow path, the control circuit 3
When the operation of the heat keeping control unit (heat keeping control means) 30a provided at 0 is instructed (S6), the heat keeping operation is performed. In the heat retention operation, when the temperature detected by the temperature sensors 32 to 34 falls to a preset reheating temperature (S
7) Then, the gas burner 21 is intermittently ignited for a predetermined time (S8), and the temperature at which the retained water causes a feeling of cold water (that is, the water temperature at which the user feels very cold when touching his hand).
This is a process of raising the temperature of the retained water before the temperature of the water decreases. The reheating temperature is set to a temperature lower by a predetermined temperature than the set temperature set as the tapping temperature. In short, the reheating temperature is set to have a fixed temperature difference from the set temperature. Here, since the heat capacity of the flow path and the retained water is relatively large, the gas burner 21
, The temperature detected by the temperature sensors 32 to 34 does not immediately rise. However, since there is a substantially constant relationship between the amount of combustion of the gas burner 21 and the rise in the temperature of the retained water, one ignition time of the gas burner 21 is set to such an extent that a predetermined rise in temperature is obtained. Further, it is not necessary to use all of the temperature sensors 32 to 34 for the temperature detection at the time of the warming operation, and only one of the temperature sensors 32 to 34 may be used.

By the way, if the stop of the heat keeping control unit 30a is instructed by the heat keeping switch 25, the heat keeping operation is not normally performed, but in the present embodiment, the stop of the heat keeping control unit 30a is instructed by the heat keeping switch 25. Also, when the hot water usage frequency is equal to or higher than a predetermined threshold value (S6), the heat retention operation is performed. That is, the control circuit 30 includes a frequency detector (frequency detector).
30b is provided, and when the stop of the heat insulation control unit 30a is instructed by the heat insulation switch 25, the flow rate sensor 3
Based on the output of No. 1, how many times the flow of water and the stoppage of water per unit time (for example, 10 minutes) are repeated is obtained as the use frequency (S9). When the usage frequency obtained by the frequency detection unit 30b becomes equal to or more than a predetermined threshold (S1).
0), the warming operation is started (S7, S8), and the temperature of the retained water is kept between the set temperature and the reheating temperature. By such an operation, even when the warming operation is not instructed by the warming switch 25, when the hot water supply and the stop are repeatedly performed within a relatively short time at the time of washing dishes, the operation can be automatically shifted to the warming operation. . The heat retention operation is automatically canceled when a certain time (for example, one hour) has elapsed since the hot water was stopped (S11, S12). The thermal insulation operation may be automatically canceled only when the thermal insulation operation is not instructed by the thermal insulation switch 25. However, even when the thermal insulation operation is instructed by the thermal insulation switch 25, the thermal insulation operation is automatically performed after a certain period of time. It is preferable to reduce the fuel gas consumption in order to reduce the fuel gas consumption.

In order to realize the above-described operation, it is necessary to change the program or the logic circuit in the conventional configuration, and it is not necessary to add a separate configuration.

[0012]

According to the present invention, there is provided a heat exchanger provided on a flow path formed between a water supply port into which water flows in and a tap hole for discharging water, and a gas burner for heating water in the heat exchanger. A flow rate sensor for detecting the flow of water into the flow path, ignition control means for igniting a gas burner when the flow rate detected by the flow rate sensor becomes a predetermined value or more, and extinguishing the gas burner when the flow rate is less than a predetermined value, and a flow rate sensor. After the detected flow rate has shifted from a state equal to or higher than a predetermined value to a state lower than the predetermined value, the gas burner is intermittently ignited to keep the water held in the flow path warm, and the heat insulation control means Insulation switch for instructing operation / stop, frequency detection means for determining the number of uses per unit time as the usage frequency from changes in the flow rate detected by the flow sensor, and stoppage of the insulation control means by the insulation switch When the usage frequency obtained by the frequency detection means is equal to or higher than the threshold when the instruction is given, the heat retention control means is operated for a fixed time, and when the operation of the heat retention control means is instructed by the heat retention switch, the gas burner is intermittently operated. To maintain the temperature of the water held in the flow path, so that there is an advantage that the feeling of cold water immediately after the start of hot water supply can be prevented even under conditions where the outside air temperature is low and the water temperature is low as in winter. Also, even when the stop of the heat retention control means is instructed by the heat retention switch, when the hot water is frequently taken out and stopped in a short time, such as when used for washing dishes, even if the hot water is temporarily stopped, the comparison can be performed. By presuming that the hot water will be reused within a short period of time and operating the heat keeping control means to keep the temperature warm, the user can be comfortably used without causing a feeling of cold water.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a schematic configuration diagram, and (b) is a block diagram around a control circuit.

FIG. 2 is an operation explanatory view of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Water supply port 12 Outlet 13 Heat exchanger 21 Gas burner 25 Insulation switch 30 Control circuit 30a Insulation control part 30b Frequency detection part 31 Flow rate sensor 32-34 Temperature sensor

Claims (1)

[Claims] 1. A heat exchanger provided on a flow path formed between a water supply port into which water flows in and a tap hole for discharging water, a gas burner for heating water in the heat exchanger, and the flow path A flow sensor for detecting water flow into the inside, ignition control means for igniting a gas burner when the flow detected by the flow sensor is equal to or more than a predetermined value and extinguishing the gas burner when the flow is less than a predetermined value, and a flow detected by the flow sensor After a transition from a state equal to or higher than a predetermined value to a state lower than the predetermined value, the gas burner is intermittently ignited to keep the water held in the flow path warm, and the operation and stop of the heat keeping control are performed. Insulation switch that is manually instructed, frequency detection means that determines the number of uses per unit time as the usage frequency from changes in the flow rate detected by the flow sensor, and shutdown of the insulation control means by the insulation switch A gas water heater characterized in that when the usage frequency obtained by the frequency detection means becomes equal to or more than a threshold value when the instruction is given, the heat retention control means is operated for a predetermined time.