JP3590964B2 - Combined water heater with heat retention function - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water heater with a warming operation function that can perform a warming operation during standby for hot water supply to appropriately raise the water temperature in the heat exchanger and prevent cold water from flowing even at the initial time when hot water is supplied. In addition, the present invention relates to a combined water heater having either a bath function or a heating function or both in addition to the hot water supply function.
[0002]
[Prior art]
Conventionally, even during standby for hot water supply, that is, even when the hot water is not being supplied, the water in the appliance is appropriately heated to improve the hot water supply performance (hereinafter, referred to as a heat retention operation function). 2. Description of the Related Art A water heater having a warming operation function such as a water heater is provided. This is because the water heater keeps the temperature of the water inside the heat exchanger by performing the combustion during the cold start and the standby of the hot water by the warming operation function of the water heater. Is prevented from flowing out, and hot water at a set temperature is promptly provided to the user.
[0003]
In this type of water heater with a heat retaining operation function, when the temperature of the water in the pipe such as the heat exchanger becomes equal to or lower than a preset temperature for preserving the combustion while the heat retaining operation is turned on, the burner causes a short time. The operation of performing the warming combustion to heat the water in the pipe and repeating the warming combustion when the water temperature becomes equal to or lower than the warming combustion start temperature is repeated. In such a heat-retaining operation, the burner is repeatedly burned. Therefore, in consideration of the durability of the parts, an interval (stand-by time) in which the heat-burning is not performed is set in advance. Control is performed to perform a heat retention operation when the temperature exceeds the limit. In addition, when the cooling speed is high, the control of stopping the warming operation is performed by giving priority to the durability because the effect of the warming operation is low.
[0004]
[Problems to be solved by the invention]
By the way, in the combined water heater, when other functions (bath or heating) are operated while the hot water supply is stopped, a fan for hot water supply combustion is rotated so that exhaust gas generated by the combustion does not flow back to the hot water supply side. As a result, there is a case where one fan is shared, and the heat exchanger on the hot water supply side is cooled by the blowing of the fan. In such a case, as in the conventional control method, even if the warming operation is performed after waiting until cooling to a certain temperature is performed, the cooling rate is too fast and the effect of the warming operation does not appear. Was controlled not to perform.
[0005]
Therefore, in the present invention, the problem of the warming operation in the combined water heater is solved, the warming operation is effective even during operation other than the hot water supply function, and the durability and safety of the burner and the like are ensured. It is an object to provide a control method.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a combined water heater with a heat retention operation function according to the present invention includes a water inlet pipe, a hot water pipe, a heat exchanger disposed between these pipes, and a heat exchanger. A hot water supply comprising at least a temperature sensor for detecting the temperature of water in the inside, and a burner mechanism for heating, and even when not supplying hot water, having a heat retaining operation function of burning the burner mechanism to perform a heat retaining operation. In the case of a combined type water heater having a function, a bath function and / or a heating function in addition to the hot water supply function, or both, and the function other than the hot water supply is operating during the warm-up operation, the temperature sensor If the temperature detected by the temperature sensor drops below a predetermined temperature, the heat-retention combustion starts when a function other than hot water supply is not activated. Start burning UNA performs control. When a function other than hot water supply is operating during the warm-up operation, a standby time is provided after the warm-up combustion, and the water temperature in the heat exchanger at the start of the warm-up combustion is detected by the temperature sensor and sent to the control unit. The stored temperature is compared with the water temperature in the heat exchanger after the elapse of the standby time, and if there is a temperature drop equal to or more than a predetermined value, warm combustion is performed. Even if it is, the process proceeds to the warming operation control when the function other than the hot water supply is not operating.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
2. Description of the Related Art Recently, a combined type water heater has been provided with a circulation circuit for circulating hot and cold water in a bath for reheating a bath and a circulation circuit for hot water for hot water heating. Here, an example of a combined water heater provided with such a circulation circuit is shown in FIG.
[0008]
The combined type water heater shown in FIG. 1 includes a hot water supply circuit A, a heating circuit B, a bath circuit C, and a drop circuit D as main parts, and these circuits provide hot water supply, heating, and bath filling and follow-up. Functions such as firing are realized.
[0009]
Specifically, the hot water supply circuit A includes a hot water supply heat exchanger 14 that is heated by the gas burner 4, and a water supply temperature sensor that detects a water supply temperature on the water supply side (water supply circuit side) of the hot water supply heat exchanger 14. A hot water temperature sensor 15 for detecting the temperature of the hot water from the hot water supply heat exchanger 14 and a water flow servo valve for limiting the hot water flow are provided on the tapping side, while a hot water supply sensor 12 for detecting the hot water supply is provided. 1 and a tapping temperature sensor 16 for detecting the tapping temperature to the outside of the water heater main body. A bypass is provided between the water inlet side and the tapping side to short-circuit the hot water supply heat exchanger 14, and a bypass valve 11 is provided on the bypass to limit the flow rate of the bypass. .
[0010]
The heating circuit B includes a heating circulation pump 31, a heating heat exchanger 22 heated by the gas burner 20, a heating temperature sensor 23 for detecting the temperature of the heating water from the heating heat exchanger 22, and an expansion for always ensuring a constant water volume. A tank 21, a bath heater 24 for bath reheating, a bath heat valve 32, and a bypass 35 are provided. The expansion tank 21 is provided with a water level electrode 33 for detecting a water level, one end of a water supply pipe 36 and one end of an overflow pipe 34 are connected, and the other end of the water supply pipe 36 is connected to the water inlet side of the hot water supply circuit A. At the same time, the other end of the overflow pipe 34 is open to the atmosphere. Further, a rehydration valve 30 is provided in the middle of the rehydration pipe 36.
[0011]
The bath circuit C has a bath heater 24 connected thereto, a pressure sensor 5 for detecting a water level in the bathtub, a bath circulation pump 3, a water flow switch 6 for detecting the presence or absence of bathtub water, and a temperature of the bathtub water. A bath temperature sensor 25 for detecting is provided. Although the configuration in which the bath heater 24 is provided is shown in the illustrated example, a bath heat exchanger may be provided in the bath circuit C instead of the bath heater 24 and heating may be performed by a gas burner.
[0012]
The drop circuit D connects between the hot water supply circuit A and the bath circuit C, and drops hot water from the hot water supply circuit A into the bathtub through the bath circuit C. In the middle of the drop circuit D, a vacuum breaker 17 is provided. A drop valve 2, a drop water amount sensor 10, and a check valve 18 are provided.
[0013]
In the combined water heater shown in FIG. 1, when performing the additional heating operation or the heating operation of the bath, the gas burner 20 is burned to heat the heating water by the heating heat exchanger 22, and the heating water and the bathtub water are separated from each other by the bath. The heat is exchanged by the heater 24 to reheat the bath, or the heating water is circulated to the outside heating circuit as it is, and the room is heated by a radiator or the like. Here, in order to burn the gas burner 20, the heating fan 8 is rotated to blow combustion air to the gas burner 20.
[0014]
The combustion exhaust gas from the gas burner 20 is discharged outside the device. However, in rare cases, the gas may flow back into the device from the outlet on the hot water supply side due to an adverse wind or the like. 7 is rotated to blow air.
[0015]
FIG. 3 shows an example of a conventional heat retaining operation in the above case. The graph shown by the solid line in FIG. 3 shows the temperature of the hot water supply heat exchanger during heating combustion, and the graph shown by the dotted line shows the temperature of the hot water supply heat exchanger when there is no heating combustion. In the case of no heating combustion, since the cooling rate of the hot water supply heat exchanger temperature is slow, if the heat exchange combustion is performed when the heat exchanger temperature T reaches the heat retention start temperature T1, the heat exchanger can be operated even after the standby time has elapsed. The temperature T is higher than T1, and the water temperature in the heat exchanger can be maintained at an appropriate temperature by repeating the short-time warm combustion. However, when there is heating combustion, the heat exchanger is rapidly cooled by the blowing of the hot water supply fan, and the heat exchanger temperature T is effective during the standby time even if the heat keeping combustion is performed after reaching the heat keeping start temperature T1. Since the temperature was lower than the temperature T2, a sufficient heat retaining operation could not be performed.
[0016]
The following two means can be considered to solve such a problem. One is to increase the warming combustion time, and the other is to shorten the waiting time between the warming combustions. However, if the warming combustion time is lengthened, the temperature rises sharply because the water is burned in a state where the water on the hot water supply is stopped, and the heat exchanger is damaged due to the pressure rise due to local boiling, There is a danger that hot water will flow out when hot water is reapplied. Further, if the standby time is shortened, the number of times of combustion increases, which may adversely affect the durability of the component. FIG. 4 shows an example of the heat retention operation when the standby time is shortened.
[0017]
The heat keeping operation control according to the present invention will be described with reference to the flowchart shown in FIG. First, the warming operation is started (the warming operation switch is turned on) in step S1, and when the hot water supply combustion is stopped in step S2, the water temperature in the heat exchanger is detected by the heat exchange temperature sensor 15 and the temperature at this time is measured. It is stored in the control unit as the exchanger initial temperature T0 (step S3).
[0018]
In step S4, it is determined whether or not heating combustion is being performed. If heating combustion is not being performed, the process proceeds to step S12, which is the same heat retention operation control as that in the related art. In step S12, if the heat exchange temperature T is equal to or lower than the heat retention start temperature T1 (for example, 45 ° C.), the process proceeds to step S13; otherwise, the process returns to step S4.
[0019]
In Step S13, a predetermined short-time warm combustion (for example, 5 seconds) is performed to appropriately raise the heat exchanger temperature, and in Step S14, operation is waited for a predetermined standby time (for example, 5 minutes). Proceed to S15. In step S15, the temperature T of the heat exchanger is detected. If the temperature is equal to or lower than the predetermined effective heat-retention temperature T2 (for example, 35 ° C.), the process proceeds to step S16, and the heat-retention operation ends. In this case, if there is a sudden decrease in temperature during the standby time, the effect cannot be expected even if the warming operation is continued, so that the warming operation is terminated with priority given to the durability of the appliance. If the heat exchanger temperature T is higher than the heat keeping effective temperature T2 in step S15, it is determined that the heat keeping operation is effective, and the process returns to step S4 to continue the heat keeping operation.
[0020]
If heating combustion is being performed in step S4, the process proceeds to step S5. In step S5, the process proceeds to step S6 when the heat exchanger temperature T drops by a predetermined temperature deviation ΔT (for example, 10 ° C.) from the heat exchanger initial temperature T0, and otherwise returns to step S4. In step S6, the heat exchanger temperature T at this time is stored in the control unit as the next heat retention start temperature Ton, and the process proceeds to the heat retention combustion in step S7. The warm combustion at this time is the same as the warm combustion performed in step S13. The heat-retention combustion time varies depending on the size of the appliance, the amount of water retained, and the like, and a short-time combustion without danger such as local boiling, pressure rise, and hot water tapping is determined by experiments.
[0021]
In step S8, similarly to step S14, the operation waits for a predetermined time, and in step S9, it is determined whether the heating combustion is continuing. If the heating combustion is finished, the process proceeds to step S12. If the heating combustion is continued, the process proceeds to step S10. In step S10, if the heat exchanger temperature T is equal to or lower than the next heat retention start temperature Ton, the process proceeds to step S11. If not, the process proceeds to step S12. To determine whether the temperature is equal to or lower than the next heat retention start temperature Ton, the temperature rise due to heat retention combustion and the temperature drop during the standby time are compared, and if it is determined that the rise is greater, there is no problem with the conventional control. This is for shifting to the conventional control.
[0022]
In step S11, similarly to step S15, the heat exchanger temperature T is detected, and if the temperature is equal to or lower than a predetermined heat retention effective temperature T2 (for example, 35 ° C.), the process proceeds to step S16 to end the heat retention operation. If the heat exchanger temperature T is higher than the heat retention effective temperature T2 in step S11, the process returns to step S6, and the heat exchanger temperature at this time is stored in the control unit as the next heat retention start temperature Ton, and the heat retention operation is repeated.
[0023]
FIG. 5 shows an example of the warming operation by the above warming operation control. It can be seen that the heat retention effect continues for a long time even during heating and combustion as compared with the operation example of FIG. In addition, the number of times of heat-retention combustion is reduced as compared with the operation example of FIG. 4, and durability is considered. In the heat retention operation control according to the present invention, the effect of the heat retention operation continues for about 30 minutes or more even during the heating combustion, and the continuous combustion time of the heating combustion is about 5 minutes in the additional heating operation of the bath, and about 5 minutes at the start of the heating operation. Considering that it is 30 minutes (after that, intermittent combustion), the heat retention operation control according to the present invention has a sufficient effect on its practicality.
[0024]
【The invention's effect】
In the heat retention operation control of the combined water heater according to the present invention, as described in claim 1, when a function other than hot water supply is operating during the heat retention operation, the detection temperature of the heat exchange temperature sensor is set to a predetermined value. When the temperature decreases by more than a predetermined value (initial temperature deviation ΔT), when the function other than the hot water supply is not operating, the detected temperature of the heat exchange temperature sensor is changed to a predetermined temperature (the heat retention start temperature T1). ) With the control to start the warming combustion when the following is detected, it is possible to start the warming operation of the hot water supply from an early stage even in the rapid cooling state where the hot water supply fan rotates due to the operation of other functions. There is an effect that the effect is maintained within a sufficiently practical range, and when other functions are not operating, unnecessary heat retention operation is not performed, so that durability is secured.
In the control according to the second aspect, the degree of cooling is determined by comparing the heat exchanger temperature before and after the warm-up combustion with the standby time. If the cooling rate is low, even if other functions are operating. Even so, by shifting to the conventional warming operation control (control in a state where other functions are not operating), an effect of preventing unnecessary warming combustion was obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a combined water heater according to the present invention.
FIG. 2 is a flowchart illustrating a warming operation control according to the present invention.
FIG. 3 is a diagram showing a change in a heat exchanger temperature by conventional heat keeping operation control.
FIG. 4 is a diagram illustrating a change in a heat exchanger temperature by a heat retention operation control when a standby time is shortened.
FIG. 5 is a diagram showing a change in a heat exchanger temperature by the heat retention operation control of the present invention.
[Explanation of symbols]
4 Hot water supply gas burner 7 Hot water supply fan 14 Hot water supply heat exchanger 15 Heat exchange temperature sensor 20 Heating gas burner 22 Heating heat exchanger 24 Bath heater T Heat exchanger temperature T0 Heat exchanger initial temperature T1 Heating start temperature T2 Heating effective temperature △ T Initial temperature Deviation Ton Next warming start temperature

Claims (2)

A water inlet pipe, a hot water pipe, a heat exchanger disposed between these pipes, a temperature sensor for detecting a water temperature in the heat exchanger, and a burner mechanism for heating. At least, even when not supplying hot water, a hot water supply function having a heat retaining operation function of burning the burner mechanism to perform a heat retaining operation, and either a bath function or a heating function other than the hot water supply function, or both. In the combined type water heater with
When a function other than hot water supply is operating during the warm-up operation, when the temperature detected by the temperature sensor drops by a predetermined value or more, the heat-retention combustion is started, and when a function other than hot water supply is not operating. Is a combined type water heater with a warming operation function, which performs control to start warming combustion when the temperature detected by the temperature sensor is equal to or lower than a predetermined temperature. A water inlet pipe, a hot water pipe, a heat exchanger disposed between these pipes, a temperature sensor for detecting a water temperature in the heat exchanger, and a burner mechanism for heating. At least, even when not supplying hot water, a hot water supply function having a heat retaining operation function of burning the burner mechanism to perform a heat retaining operation, and either a bath function or a heating function other than the hot water supply function, or both. In the combined type water heater with
If a function other than hot water supply is operating during the warm-up operation, a standby time is provided after the warm-up combustion, and the water temperature in the heat exchanger at the start of the warm-up combustion is detected by the temperature sensor and stored in the control unit. Then, in comparison with the water temperature in the heat exchanger after the elapse of the standby time, if there is a temperature drop of a predetermined value or more, warm combustion is performed, and if there is no temperature drop of a predetermined value or more, functions other than hot water supply are activated. A combined type water heater with a warming operation function, characterized in that even if it is in operation, the process shifts to a warming operation control when a function other than the hot water supply is not operating.

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