JP3067418B2 - Water heater control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a hot water supply system in which hot water supplied through a heat exchanger is mixed with water by using a bypass to supply hot water at a predetermined hot water supply temperature.

[0002]

2. Description of the Related Art A conventional water heater of this type will be briefly described with reference to FIG. 1. Water supplied to a water inlet passage 10 is heated by a burner 21 in an instantaneous heat exchanger 20 and discharged to a tap water passage 30. You. On the other hand, the water is mixed into the hot water supply path 30 by the water mixing control valve 41 through the bypass 40 branched from the water supply path 10, whereby hot water at a predetermined hot water supply temperature is supplied. Further, in the previous water heater, the burner 21 and the instantaneous heat exchanger 20 directly adjust the hot water supply temperature without mixing water by the bypass 40 (the bypass 40 in FIG. 1 is not provided). I was In the water heater before the water mixing is not performed, one of the goals is to quickly adjust the outlet temperature from the heat exchanger 20 to the set hot water supply temperature. Therefore, as shown in FIG. The tapping temperature T _K from the heat exchanger 20 is suddenly adjusted (as indicated by A in FIG. 4) by, for example, rapidly changing the combustion amount of the fuel cell 21. The tendency of the rapid adjustment of the tapping temperature T _K in the water heater before the water mixing was not performed is due to the subsequent bypass.
In the mixed water heater using the water heater 40, the re-water supply is started, and as shown in FIG. 5, the tapping temperature T _K from the instantaneous heat exchanger 20 is changed to the set hot water supply temperature. The temperature was suddenly adjusted (shown by B in FIG. 5) to the original hot water temperature calculated from the incoming water temperature and the bypass water mixing ratio.

[0003]

However, in a mixed water heater, if the temperature of the hot water from the heat exchanger 20 is sharply adjusted as described above, a sudden change in the hot water temperature will cause another problem. The water mixing control valve 41 of the bypass 40, which is a hot water supply temperature adjusting means, also requires abrupt operation, and as a result, there is a problem that the load on the water mixing adjusting valve, its driving means, and the control means is heavy.

Accordingly, the present invention solves the above-mentioned drawbacks of the prior art, eliminates a rapid change in the tapping temperature from the heat exchanger at the initial stage of refilling in a mixed water heater, and provides a stable and gentle temperature. It is an object of the present invention to provide a method for controlling a water heater in which the load on the bypass water mixing regulating valve is reduced by adjusting the temperature of the hot water supply to the hot water supply temperature.

[0005]

In order to achieve the above-mentioned object, the present invention provides a method of heating water from an inlet channel with an instantaneous heat exchanger to supply hot water to a hot water channel, and connecting a bypass from the water inlet channel to a hot water channel. A method of controlling a water heater that mixes water and adjusts water to a predetermined set hot water supply temperature to perform hot water supply.When re-hot water supply is performed, the set hot water supply temperature, the incoming water temperature, and The original set hot water temperature to be discharged from the instantaneous heat exchanger is calculated from the distribution ratio by the bypass water mixing regulating valve, and further, an intermediate temperature between the calculated original hot water temperature and the set hot water supply temperature is calculated. Then, combustion is performed using this as the initially set tapping temperature, and the set tapping temperature is raised to the original set tapping temperature over a certain period of time thereafter.

[0006]

According to the above-mentioned feature of the present invention, in the mixed water heater, since the hot water from the heat exchanger is not always the last hot water, the temperature of the hot water from the heat exchanger in the initial stage of re-hot water supply is immediately determined. Instead of using the original set hot water temperature calculated with respect to the set hot water supply temperature, an intermediate temperature is gradually adjusted to the set hot water temperature. That is, first, an intermediate temperature between the set hot water supply temperature and the original set hot water temperature is selected as an appropriate hot water temperature to be adjusted first in the initial stage of re-hot water supply, that is, an initial set hot water temperature. Thus, the tapping temperature at an appropriate temperature lower than the original setting tapping temperature is achieved without the tapping temperature of the heat exchanger from the heat exchanger in the initial stage of the re-supplying water being too high and, of course, not lower than the set tapping temperature. And since the set tapping temperature is raised gently over a certain period of time, the change of the actual tapping temperature does not change suddenly, so the set water supply adjusting valve does not need to be moved suddenly. Water mixing adjustment to temperature can be performed.

[0007]

FIG. 1 is an overall configuration diagram of a water heater in which the method of the present invention is implemented, FIG. 2 is a flowchart showing a control example, and FIG. 3 is an initial hot water supply and heat exchange at the time of re-water supply according to the method of the present invention. It is a figure which shows the tapping characteristic from a vessel.

In the water heater shown in FIG. 1, the water supplied to the water inlet 10 is heated by the instantaneous heat exchanger 20 and discharged to the hot water outlet 30. From the water inlet channel 10, a bypass 40 is connected to the hot water channel 30.
And are adapted to mix water. The inlet channel 10 is provided with an inlet temperature sensor 11 and an inlet flow sensor 12. The instantaneous heat exchanger 20 has a gas burner 21.
Is provided. Further, a tapping temperature sensor 31 is provided in the tapping path 30, and a tapping temperature sensor 51 is provided in a tapping water path 50 of the tapping path 30 downstream of a point 32 to which the bypass 40 is connected. A water regulating valve 41 and a drive unit 42 thereof are provided. Reference numeral 60 denotes a controller with a built-in microcomputer for controlling the entire water heater, which inputs information from the sensors 11, 12, 31, and 51 and a command from a remote controller (not shown), performs calculations in accordance with a predetermined program, and performs operations to the respective parts 21 and 41. Output a control signal.

Next, a method of controlling the water heater by the controller 60 will be described with reference to FIGS. Now, a hot water supply curl (not shown) is reopened in the water heater, re-water supply is started (YES in S1), and the burner 21 is ignited (YES in S2).
First calculates the original set tap temperature T _{KS at} which the heat exchanger 20 should tap water from the set hot water supply temperature T _QS , the incoming water temperature T _C, and the distribution ratio _KBKO by the water mixing regulating valve 41 at the start of re-hot water supply ( S
3). Now the amount of water the Q _BO to the bypass 40 side by the distribution ratio K _BKO at the start re hot water supply, when the amount of water to the heat exchanger 20 side and Q _KO, the next number 1, number 2 is established.

[0010]

[Number 1] _{T QS (Q BO + Q KO} ) = T C · Q BO + T KS · Q KO T QS: set hot water supply temperature T _C: incoming water temperature T _KS: original configuration of the heat exchanger the hot water temperature Q _BO: distribution The amount of water to the bypass 40 side at the rate K _BKO Q _KO : The amount of water to the heat exchanger 20 side at the distribution rate K _BKO

[0011]

[Number 2] _{K BKO = Q BO / Q KO} K BKO: distribution ratio at the start of re-hot water supply Q _BO: water Q _KO to the bypass 40 side in the distribution ratio K _BKO: heat exchanger 20 in the distribution ratio K _BKO Amount of water to the side

From the above equations (1) and (2), the original set hot water temperature T _{KS of} the heat exchanger 20 can be obtained by the following equation (3).

[0013]

[Number 3] _{T KS = T QS (1 +} K BKO) -T C · K BKO T KS: the original setting of the heat exchanger hot water temperature T _QS: Set hot water supply temperature T _C: incoming water temperature K _BKO: re-hot water supply at the start of Distribution rate

In the above, the original set tap temperature T _KS of the heat exchanger is set.
Is calculated, the controller 60 further calculates the first appropriate tapping temperature to be adjusted in the initial _stage of re-hot water supply, that is, the initial setting tapping temperature T _KSO , and the set tapping temperature T _KSt at regular intervals thereafter. 4. Calculate using Equation 5 (S
4).

[0015]

## EQU4 ## T _KSO = 1/2 (T _QS + T _KS ) T _KSO : Initial tap water temperature at the time of re-hot water supply by heat exchanger 20 T _QS : Set hot water supply temperature T _KS : Original set tap water temperature of heat exchanger

[0016]

[ _Equation 5] T _KSt = T _KSO + Kt T _KSt : Set tap temperature at fixed time intervals after start of re-hot supply T _KSO : Initial set tap temperature at re-hot water supply by heat exchanger 20 K: Constant t: Unit time

The Kt is, for example, 1 ° C. every 0.5 seconds.
The expression can be ascending. However, the numerical value is not particularly limited. Further, in the above equation 4, the initial set tapping temperature T _KSO is set to the midpoint temperature between the set hot water supply temperature T _QS and the original set tapping temperature T _KS of the heat exchanger. I just need.

As described above, the initially set tapping temperature T _KSO
When the set tapping temperature T _KSt is calculated for each fixed time period thereafter, the required amount of combustion heat is calculated, the required gas amount is calculated (S5), and the new gas amount calculated for each fixed time period is calculated. Feed forward supplied (S
6). This control operation is continued until the set tapping temperature T _KSt reaches the original set tapping temperature T _KS , and ends.

If the start of hot water supply is not re-hot water supply in S1, feedforward control is performed so that the original set hot water temperature T _KS of the heat exchanger 20 is maintained from the beginning. Whether or not the hot water supply is re-hot water supply may be determined, for example, based on whether or not a predetermined time or more has elapsed since the last use.

[0020]

According to the water heater control method according to the first aspect of the present invention, when the hot water is re-supplied, the set hot water supply temperature, the incoming water temperature, and the bypass water mixture are provided. From the distribution ratio by the regulating valve, calculate the original set hot water temperature to be discharged from the instantaneous heat exchanger, and further obtain an intermediate temperature between the calculated original set hot water temperature and the set hot water supply temperature, Since this was performed as the initial set hot water temperature and combustion was performed over a certain period of time, the set hot water temperature was raised to the original hot water temperature.
The actual hot water from the instantaneous heat exchanger in the initial stage of re-hot water supply can be gently adjusted from an appropriate temperature to the original set hot water temperature without a sudden change in up and down. The water mixture can be adjusted to the required set hot water supply temperature without requiring a sudden movement operation. As a result, the hot water supply temperature after mixing can be stably adjusted to the hot water supply temperature, the load on the control of the mixing water adjustment valve is light, and the purpose can be sufficiently achieved with simple control and driving means. became.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a water heater in which a method of the present invention is performed.

FIG. 2 is a flowchart showing a control example of the method of the present invention.

FIG. 3 is a diagram showing characteristics of initial hot water supply and hot water supply from a heat exchanger when re-hot water is supplied according to the method of the present invention.

FIG. 4 is a diagram showing an initial hot water supply characteristic at the time of re-hot water supply according to the conventional method.

FIG. 5 is a diagram showing characteristics of initial hot water supply and hot water supply from a heat exchanger at the time of re-hot water supply according to another conventional method.

[Explanation of symbols]

 10 Inlet channel 11 Inlet temperature sensor 20 Instantaneous heat exchanger 21 Burner 30 Outlet channel 31 Outlet temperature sensor 40 Bypass 41 Water mixing regulating valve 42 Drive unit 50 Hot water channel 51 Hot water temperature sensor 60 Controller

Claims (1)

(57) [Claims] 1. A system according to claim 1, wherein the water from the water inlet is heated by an instantaneous heat exchanger to supply the hot water to the hot water outlet, and a bypass from the water inlet is connected to the hot water outlet to mix the water. The method of controlling a hot water supply, wherein the instantaneous heat exchanger is adjusted based on a set hot water supply temperature, an input water temperature, and a distribution ratio by a bypass mixing control valve when re-heating is performed. From the calculated original set hot water temperature and the set hot water supply temperature, calculate an intermediate temperature between them, perform combustion as the initial set hot water temperature, and thereafter perform combustion. A method for controlling a water heater, wherein the set tapping temperature is raised to the original set tapping temperature over a certain period of time.