JP2022150050A - water heater - Google Patents

Abstract

To provide a water heater capable of improving stability of hot water supply temperature even when determining a bypass ratio by using a heat exchanger hot water tapping temperature detected by a heat exchanger hot water temperature sensor.SOLUTION: A water heater 1 includes a control part 50 which determines a bypass ratio as a mixing rate of heat exchanger water passing quantity and bypass water passing quantity to control an opening of a bypass valve 34 on a bypass merging part 25. The control part 50 determines a bypass ratio BF by using a heat exchanger hot water tapping temperature, the heat exchanger hot water tapping temperature used for determination of the bypass ratio BF can be replaced for a relative heat exchanger hot water tapping temperature Thexx as a heat exchanger hot water tapping temperature Thex detected in the past, in place of present heat exchanger hot water tapping temperature Thex detected by a heat exchanger hot water tapping temperature sensor 32, and the relative heat exchanger hot water tapping temperature Thexx is constituted to use the past heat exchanger hot water tapping temperature Thex which goes back from the present to the past by a going-back time Tx required until hot water flowing through a hot water tapping passage 21 arrives at a bypass merging part 25 from a position of the heat exchanger hot water tapping temperature sensor 32.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a hot water supply apparatus having a bypass passage that short-circuits a water supply passage and a hot water discharge passage to bypass a heat exchanger.

In this type of water heater, the mixing ratio (bypass ratio) of the hot water from the hot water supply passage connected to the outlet side of the heat exchanger and the water from the bypass passage is used so that hot water with a set hot water supply temperature can be obtained. is known to perform bypass mixing control to control the degree of opening of the bypass valve (for example, Patent Literature 1). Conventionally, as a bypass mixing control of hot water supply equipment, the hot water supply temperature at the time of re-discharging hot water is calculated by calculating the bypass ratio based on the deviation between the heat exchange outlet hot water temperature, which is the temperature of the hot water generated by the heat exchanger, and the hot water supply set temperature. (Patent Document 2).

JP 2017-75750 A JP-A-8-5144

However, the heat exchange outlet water temperature sensor for detecting the heat exchange outlet water temperature is attached near the heat exchanger outlet in the hot water outlet path, while the bypass junction where the bypass passage joins the hot water outlet path is not suitable for the structure of the device. is provided at a downstream position away from the vicinity of the heat exchanger outlet. In this way, unlike the installation position of the heat exchange outlet hot water temperature sensor and the position of the bypass junction, they are separated by a certain distance. Therefore, it takes a certain amount of time for the hot water flowing through the outlet hot water passage to reach the bypass junction from the position of the heat exchange outlet hot water temperature sensor. There may be a difference in the temperature of the hot water on the side of the hot water outlet passage at the confluence. In this case, if the bypass ratio is determined using the temperature of the heat-exchanged hot water detected by the heat-exchanged hot water temperature sensor, the actual hot water supply temperature may deviate from the target hot water supply set temperature in the transitional period when the opening of the bypass valve is changed. There was a risk of slipping. For example, under hot water supply conditions in which temperature control is performed at a heating amount lower than the minimum number while alternately repeating burner ignition and extinguishing due to burner combustion, and a low amount of hot water is required, depending on the change in the heating amount of the burner, The change in the temperature of the hot water discharged from the heat exchanger becomes remarkable, and the time required for the hot water discharged from the heat exchanger to reach the bypass junction becomes longer. Therefore, the temperature difference between the temperature of the hot water flowing through the hot water outlet passage and the position of the heat exchange outlet hot water temperature sensor and the position of the bypass confluence becomes large, and the deviation of the actual hot water supply temperature from the target hot water supply set temperature becomes noticeable. there was a case.

The present invention has been made in view of the above-mentioned circumstances, and makes it possible to increase the stability of the hot water supply temperature even when the bypass ratio is determined using the heat exchanged hot water temperature detected by the heat exchanged hot water temperature sensor. An object of the present invention is to provide a water heater that

The water heater according to the present invention includes:
A heat exchanger heated by a burner, a water supply passage for supplying water to the heat exchanger, a hot water outlet passage connected to the heat exchanger for outflow of hot water produced by the heat exchanger, and a short circuit between the water supply passage and the hot water outlet passage. a bypass valve that increases or decreases the flow rate of water passing through the bypass passage; A heat exchanger output hot water temperature sensor that detects in the hot water outlet passage upstream of the bypass junction where the passage joins, and a heat exchanger communication from the hot water outlet passage in the bypass confluence so that hot water with a set hot water supply temperature can be obtained. A hot water supply apparatus comprising: a control unit that determines a bypass ratio, which is a mixing ratio of a water volume and a bypass water flow volume from a bypass passage, and controls an opening degree of a bypass valve,
The control unit
The heat-exchanged hot water temperature is used to determine the bypass ratio, and the heat-exchanged hot water temperature used for determining the bypass ratio is the current heat-exchanged hot water temperature detected by the heat-exchanged hot water temperature sensor. Instead, it is possible to replace the previously detected heat exchange outlet hot water temperature with the relative heat exchange outlet hot water temperature,
The relative heat-exchanged hot water temperature is the past heat-exchanged hot water temperature that goes back from the present to the past by the time required for the hot water flowing through the hot water outlet passage to reach the bypass junction from the position of the heat-exchanged hot water temperature sensor. This configuration is used.

According to the above configuration, even if the positions of the bypass confluence and the heat exchange outlet water temperature sensor are different, the current (current) heat exchange outlet water temperature at the bypass confluence is determined by using the relative heat exchange outlet water temperature. can be obtained. Therefore, by determining the bypass ratio using the relative heat exchange output hot water temperature and controlling the opening degree of the bypass valve, it is possible to supply hot water while suppressing the deviation of the actual hot water supply temperature from the hot water supply set temperature. For example, even if a small amount of hot water is required and it takes a relatively long time for the hot water from the heat exchanger to reach the bypass confluence, the hot water supply temperature can be adjusted so that there is no error from the hot water supply set temperature. can. Therefore, even when the bypass ratio is determined using the heat-exchanged hot water temperature detected by the heat-exchanged hot water temperature sensor, the stability of the hot water supply temperature can be improved by using the relative heat-exchanged hot water temperature.

The control unit
continuously storing the temperature of the heat-exchanged hot water detected by the heat-exchanged hot water temperature sensor as a stored value at regular time intervals;
calculating the retrogression time from the ratio of the current heat exchanger water flow rate to the volume of the hot water outlet passage from the position of the heat exchange hot water temperature sensor to the position of the bypass junction;
A configuration may be provided in which the bypass ratio is calculated using a stored value of the heat exchange outlet hot water temperature before the retroactive time from the current time as the relative heat exchange outlet hot water temperature.

The retrogression time corresponds to the time required for the hot water flowing out of the heat exchanger and flowing through the hot water outlet passage to reach the bypass junction from the position of the heat-exchanged hot water temperature sensor. Therefore, the relative heat exchange outlet hot water temperature, which is the stored value of the heat exchange outlet hot water temperature before the retroactive time from the present (current time), is the temperature of the hot water on the outlet passage side that reaches the bypass junction at the present time. will be shown. That is, the accurate temperature of the current heat-exchanged hot water at the bypass confluence can be obtained from the relative heat-exchanged hot water temperature based on the retrogression time and the stored value. Therefore, the bypass ratio can be accurately determined so that the actual hot water supply temperature does not deviate from the hot water supply set temperature. Therefore, in the hot water temperature adjustment by the bypass mixing control, the hot water temperature can be adjusted so as to obtain the hot water supply temperature without error from the hot water supply set temperature, and the stability of the hot water supply temperature can be improved.

The control unit
The operation of determining the bypass ratio and controlling the opening degree of the bypass valve using the relative heat exchange outlet water temperature may be configured to be executed when the burner temperature is adjusted while alternately repeating ignition and extinguishing. can.

As a result, even when the temperature of the hot water supplied from the heat exchanger changes significantly in accordance with the change in the heating amount of the burner, it is possible to adjust the temperature of the hot water to be supplied without error from the hot water supply set temperature.

1 is a schematic diagram showing an internal configuration of a water heater according to an embodiment; FIG. FIG. 4 is a process diagram for explaining bypass mixing control processing in the hot water supply apparatus according to the embodiment; It is a graph which shows transition of the hot water supply temperature when a bypass mixing process is performed, the figure (a) is an Example of this invention, and the figure (b) is a comparative example.

EMBODIMENT OF THE INVENTION Below, it demonstrates, referring an accompanying drawing for embodiment of this invention.
As shown in FIG. 1, the water heater 1 of the embodiment includes a heat exchanger 10 for generating hot water, a combustion chamber 11 having a burner 12 for heating the heat exchanger 10, piping, and a control unit 50. I have. Fuel gas is supplied to the burner 12 through a gas passage 13, and the gas passage 13 is provided with a gas proportional valve 14 for controlling the flow rate of the fuel gas. A combustion fan 15 for supplying combustion air for the burner 12 is connected to the combustion chamber 11 .

A water supply passage 20 is connected to the upstream side of the heat exchanger 10 , and a hot water discharge passage 21 is connected to the downstream side of the heat exchanger 10 . The water supply passage 20 and hot water outlet passage 21 are short-circuited by a bypass passage 22 . Therefore, part of the water flowing through the water supply passage 20 is diverted to the bypass passage 22 before it flows into the heat exchanger 10, and the rest flows into the heat exchanger 10 and is heated before flowing out to the hot water discharge passage 21. do. The hot water flowing out to the hot water outlet passage 21 is mixed with the water flowing through the bypass passage 22 at a bypass junction part 25 where the hot water outlet passage 21 joins the bypass passage 22, and then supplied to the hot water outlet plug 24.例文帳に追加A bypass valve 34 is provided in the bypass passage 22 , and the amount of water flowing through the bypass passage 22 is controlled by adjusting the degree of opening of the bypass valve 34 . In this specification, the piping extending from the hot water supply passage 21 on the downstream side of the bypass junction 25 is referred to as the hot water supply passage 23 to distinguish it from the hot water supply passage 21 on the upstream side of the bypass junction 25 . Therefore, when simply referred to as the hot water outlet passage 21, it indicates the passage from the outlet of the heat exchanger 10 to the bypass confluence portion 25, and when referred to as the hot water supply passage 23, it indicates the passage from the bypass confluence portion 25 to the hot water outlet plug 24. shall be shown.

Water supply passage 20 has a water supply temperature sensor 31 for detecting the temperature of water supplied to hot water supply device 1 (hereinafter referred to as water supply temperature), and a water supply temperature sensor 31 for detecting the amount of water supplied to hot water supply device 1 (hereinafter referred to as water supply amount). A flow sensor 30 is provided. The flow rate sensor 30 is provided upstream of a position where the bypass passage 22 branches from the water supply passage 20 . Therefore, the flow rate sensor 30 detects the sum of the amount of water flowing into the heat exchanger 10 and the amount of water branched to the bypass passage 22 (thus, the amount of hot water flowing through the hot water supply passage 23). become. A heat-exchanged hot water temperature sensor 32 for detecting the temperature of the hot water generated by the heat exchanger 10 (hereinafter referred to as heat-exchanged hot water temperature) is attached to the hot water outlet passage 21 near the outlet of the heat exchanger 10 . A hot water supply temperature sensor 33 is attached to the hot water supply passage 23 to detect the temperature of the hot water after the hot water from the hot water outlet passage 21 and the water from the bypass passage 22 are mixed at the bypass confluence portion 25 (hereinafter referred to as hot water temperature). there is

The control unit 50 includes various control circuits such as a control circuit for adjusting the temperature of the hot water to be supplied (control of the heating amount of the burner 12, control of the degree of opening of the bypass valve 34, etc.), memory for storing programs and data, etc. A timer or the like for measuring time is provided. A flow rate sensor 30 , a water supply temperature sensor 31 , a heat exchange hot water temperature sensor 32 , and a hot water supply temperature sensor 33 are connected to the control unit 50 . A remote controller 51 is connected to the controller 50, and the user of the water heater 1 operates the remote controller 51 to set the temperature of the hot water to be supplied from the hot water tap 24, start/stop the hot water supply operation, and the like. be able to.

Next, the hot water supply operation of the hot water supply apparatus 1 of the embodiment will be described. Note that the processing of the operation of the hot water supply operation is executed by the control unit 50 .
When the hot water tap 24 is opened and the flow rate sensor 30 detects the amount of working water flowing through the water supply passage 20, the combustion fan 15 is operated at a predetermined rotational speed, the gas proportional valve 14 is opened, and the burner 12 is ignited. do. As a result, the hot water supply operation is started. When the hot water supply operation is started, the temperature of the hot water to be supplied is adjusted to the hot water supply set temperature. This temperature adjustment is performed by controlling the amount of heat generated by the burner 12 and bypass mixing control for controlling the degree of opening of the bypass valve 34 .

The heating amount of the burner 12 is controlled by determining the heating amount of the burner 12 based on the hot water supply set temperature, the heat exchange hot water temperature, the water supply temperature, the water supply water amount, etc., and according to the determined heating amount, the burner combustion size, the burner The combustion state of the burner 12 is controlled under predetermined operating conditions such as on/off control of combustion (control of alternately repeating ignition and extinguishing of the burner 12). Further, the bypass mixing control determines a bypass ratio, which is a mixing ratio of the heat exchanger water flow rate on the hot water discharge passage 21 side and the bypass water flow rate on the bypass passage 22 side, in the bypass merging portion 25, and the determined bypass ratio is obtained. The degree of opening of the bypass valve 34 is controlled as follows. Through these controls, the hot water supply temperature of hot water obtained from the hot water tap 24 is adjusted to the hot water supply set temperature. When adjusting the temperature, it is necessary to prevent the temperature of the heat exchanger 10 from becoming too high, causing boiling in the heat exchanger 10, or the temperature of the heat exchanger 10 from becoming low, which tends to cause drainage. Therefore, the temperature of the heat-exchanging hot water can be kept within a predetermined temperature range.

The bypass mixing control in this embodiment will be described below.
Referring to FIG. 2, when the hot water supply operation is started, in step S1, control unit 50 changes the heat exchange outlet hot water temperature Thex detected by heat exchange outlet hot water temperature sensor 32 to a predetermined time (for example, 0.5 seconds). (every time), it is continuously stored in the memory as a stored value for the most recent arbitrary time (for example, 60 seconds).

Next, in step S2, the control unit 50 calculates the backward time Tx, which is the time required for the hot water flowing through the hot water outlet passage 21 to reach the bypass confluence section 25 from the position of the heat exchange hot water temperature sensor 32, by the following equation: Obtained by (1).

In equation (1), Tx is the backward time, Nv is the water volume of the hot water outlet passage 21 from the position of the heat exchange outlet hot water temperature sensor 32 to the bypass junction 25, Win is the current supply water amount, Bpnow is the current bypass ratio, respectively. In this specification, "currently" means the present time.

The volume Nv is obtained from the product of the cross-sectional area of the hot water outlet passage 21 and the length of the hot water outlet passage 21 from the position of the heat exchange outlet hot water temperature sensor 32 to the bypass junction portion 25, and is stored in the controller 50 in advance. The current water supply amount Win is acquired based on the current detection value detected by the flow rate sensor 30 . The current bypass ratio Bpnow is determined by the control section 50 and stored in the control section 50 . Note that the bypass ratio Bpnow at the start of the hot water supply operation may be such that the bypass valve 34 is in a constant opening or closed state.

The value of the denominator in the above formula (1) indicates the current water flow through the heat exchanger. That is, according to the above equation (1), by dividing the water volume Nv of the hot water discharge passage 21 from the position of the heat exchange hot water temperature sensor 32 to the position of the bypass junction portion 25 by the current heat exchanger water flow rate, A retrogression time Tx, which is the time required for the hot water flowing through the passage 21 to reach the bypass confluence portion 25 from the position of the heat-exchanged hot water temperature sensor 32, is obtained. The calculation of the backward time Tx is not limited to the case where the calculation is performed by the above equation (1), but may be read from the data table or the like according to the above equation (1).

Then, when the retroactive time Tx is obtained, in step S3, the control unit 50 reads from the memory the stored value of the heat exchange outlet hot water temperature Thex for the retroactive time Tx before the present, and stores the read stored value as a relative value. Obtained as the heat exchange outlet water temperature Thexx. When the stored value of the heat exchange hot water temperature Thex for the retroactive time Tx is not yet stored in the memory at the beginning of the hot water supply operation, for example, the oldest stored value among the stored values in the memory is set to the relative heat exchange hot water temperature. An arbitrary stored value among the stored values of the memory, or the heat exchanged hot water temperature Thex currently detected by the heat exchanged hot water temperature sensor 32 is regarded as the relative heat exchanged hot water temperature Thexx can be considered as

Next, in step S4, the control unit 50 determines the bypass ratio BF based on the heat exchange outlet hot water temperature Thex, the hot water supply set temperature Tqset, and the water supply temperature Tin. However, in the present embodiment, instead of the current heat-exchanged hot water temperature Thex detected by the heat-exchanged hot water temperature sensor 32, the heat-exchanged hot water temperature Thex used to determine the bypass ratio BF is set to the relative heat-exchanged hot water temperature Replace with Thexx. That is, the bypass ratio BF for setting the degree of opening of the bypass valve 34 is obtained by the following equation (2).

In Equation (2), the relative heat exchange exit hot water temperature Thexx is a stored value of the past heat exchange exit hot water temperature Thex acquired in step S3. The hot water supply set temperature Tqset is a set value of the hot water supply temperature of hot water supplied from the hot water tap 24, and is set in advance for the controller 50 by the user operating the remote control 51. FIG. The feed water temperature Tin is acquired based on the current detection value detected by the feed water temperature sensor 31 .

The formula (2) is based on the thermal equilibrium relationship that the amount of heat released from hot water from the hot water supply passage 21 and the amount of heat absorbed from the water from the bypass passage 22 are equal at the bypass confluence portion 25. It is a relational expression for calculating a bypass ratio BF as a mixing ratio of the heat exchanger water flow rate and the bypass water flow rate (bypass water flow rate/heat exchanger water flow rate). In the above formula (2), the bypass ratio BF is calculated as the ratio of the bypass water flow rate when the heat exchanger water flow rate is 1. However, when the value of the bypass ratio BF calculated by the formula (2) is less than 0 (BF<0), the bypass ratio BF=0. The calculation of the bypass ratio BF is not limited to the calculation using the formula (2), and may be read from the data table or the like based on the formula (2).

Then, when the bypass ratio BF using the relative heat exchange outlet hot water temperature Thexx is calculated by the processing in step S4, the control unit 50 adjusts the opening degree of the bypass valve 34 according to the bypass ratio BF in step S5. Instruct to set. As a result, the degree of opening of the bypass valve 34 is set to the degree of opening corresponding to the bypass ratio BF.

The operation of controlling the degree of opening of the bypass valve 34 described above, that is, the operation of the bypass mixing control is performed from the beginning of the hot water supply operation to the end of the operation.

As described above, according to the hot water supply apparatus 1 of the present embodiment, the relative heat exchange outlet hot water temperature Thexx is used to determine the bypass ratio in the bypass mixing control. Even if the position of the sensor 32 is different, the current heat-exchanged hot water temperature (relative heat-exchanged hot water temperature Thexx) at the bypass junction section 25 can be acquired. That is, the retrogression time Tx is the time required for the hot water flowing out of the heat exchanger 10 and flowing through the hot water outlet passage 21 to reach the bypass junction portion 25 from the position of the heat exchange outlet hot water temperature sensor 32 . The relative heat-exchanged hot water temperature Thexx is a stored value of the heat-exchanged hot water temperature Thex before the retroactive time Tx from the present, among the stored values of the past heat-exchanged hot water temperature Thex, and is the current bypass junction part. This indicates the temperature of the hot water reaching 25 on the side of hot water discharge passage 21 . In this manner, the current accurate temperature of the heat-exchanged hot water at the bypass confluence section 25 can be obtained from the relative heat-exchanged hot water temperature Thexx based on the retrogression time Tx and the stored values of the heat-exchanged hot water temperature Thex.

Therefore, the bypass ratio BF can be accurately determined so that the actual hot water supply temperature does not deviate from the hot water supply set temperature Tqset. Therefore, by determining the bypass ratio BF using the relative heat exchange output hot water temperature Thexx, it is possible to supply hot water while suppressing the deviation of the actual hot water supply temperature from the hot water supply set temperature Tqset. Therefore, in adjusting the temperature of hot water by the bypass mixing control, it is possible to adjust the hot water supply temperature to a hot water supply temperature with no error from the hot water supply set temperature Tqset, and it is possible to improve the stability of the hot water supply temperature.

For example, when the temperature is adjusted by alternately repeating ignition and extinguishing on the burner 12 side, the heat exchange discharge hot water temperature Thex changes frequently according to changes in the heating amount of the burner 12 . As a result, the difference in the temperature of the hot water flowing through the outlet hot water passage 21 between the position of the heat exchange outlet hot water temperature sensor 32 and the position of the bypass junction 25 becomes large, and the actual hot water supply temperature deviates from the target hot water supply set temperature Tqset. may become noticeable. However, even in such a case, the opening of the bypass valve 34 can be set with an appropriate bypass ratio BF at an appropriate timing for changes in the heat exchange hot water temperature Thex accompanying ignition and extinguishing of the burner 12. The temperature can be adjusted so as to obtain a hot water supply temperature that does not have an error with the temperature Tqset.

Therefore, even when the bypass ratio BF is determined using the heat-exchanged hot water temperature Thex detected by the heat-exchanged hot water temperature sensor 32, the currently detected heat-exchanged hot water temperature Thex is replaced with the relative heat-exchanged hot water temperature By using Thexx, it is possible to improve the stability of the hot water supply temperature.

Other form 1
In another form 1, the control unit 50 determines the bypass ratio BF using the relative heat exchange outlet hot water temperature Thexx and performs bypass mixing control when the requested hot water supply amount is low (for example, the water supply amount is 3 L/min or less). When the amount of water is not low, the bypass ratio is determined by another method such as using the heat exchanged hot water temperature Thex detected by the heat exchanged hot water temperature sensor 32 to perform bypass mixing control, or the bypass valve 34 may be maintained at a constant opening. As a result, even if it takes a relatively long time for the hot water coming out of the heat exchanger 10 to reach the bypass confluence portion 25 due to the low water volume, the relative heat exchange hot water temperature Thexx is used to determine the bypass ratio BF. By doing so, hot water can be supplied while suppressing deviation of the actual hot water supply temperature from the hot water supply set temperature Tqset.

Other form 2
In another form 2, the control unit 50 determines the bypass ratio BF using the relative heat exchange outlet hot water temperature Thexx, and performs bypass mixing control while the burner 12 alternately repeats ignition and extinguishing. It is configured to be executed when the temperature is adjusted with a lower burner heating amount. When the heating amount of the burner 12 is equal to or higher than the minimum number, the bypass ratio is determined by another method such as using the heat exchanged hot water temperature Thex detected by the heat exchanged hot water temperature sensor 32, and bypass mixing control is performed. Alternatively, the degree of opening of the bypass valve 34 may be maintained at a constant degree of opening. As a result, even when the change in the heat exchange outlet hot water temperature Thex becomes remarkable in accordance with the change in the heating amount of the burner 12, by determining the bypass ratio BF using the relative heat exchange outlet hot water temperature Thexx, the actual It is possible to supply hot water while suppressing deviation of the hot water supply temperature from the set hot water supply temperature Tqset.

Next, tests were conducted to confirm the effects of the present invention, which will be described below. In this test, a hot water supply apparatus corresponding to the configuration of the hot water supply apparatus 1 shown in FIG. The state of the hot water supply temperature (detected value of the hot water supply temperature sensor 33) when the bypass mixing control was performed under the condition that ignition and extinguishing were alternately repeated was measured.

FIG. 3 is a graph showing the results of this test, and FIG. 3(a) shows an embodiment of the present invention. FIG. 3B shows a comparative example in which bypass mixing control is performed using a bypass ratio calculated using the heat exchanged hot water temperature Thex currently detected by the heat exchanged hot water temperature sensor 32. shows the hot water supply temperature when

In the comparative example, as shown in FIG. 3B, when the degree of opening of the bypass valve 34 is controlled so as to increase the degree of opening of the bypass valve 34 (increase the bypass ratio) due to the rise in the temperature of the heat exchanged hot water. When the temperature of the hot water supplied drops, and when the opening of the bypass valve 34 is controlled so as to decrease the opening of the bypass valve 34 (reduce the bypass ratio) due to the drop in the temperature of the hot water supplied from heat exchange, the temperature of the hot water supplied rises. It was observed. From this, it is considered that the timing of the control of the degree of opening of the bypass valve 34 is slightly earlier.

The hot water supply temperature of the comparative example had a maximum value of 40.9°C, a minimum value of 37.9°C, and an average value of 38.9°C. That is, the average value of the hot water supply temperature has a deviation (temperature difference) of 1.1°C from the hot water supply set temperature of 40°C, 2.0°C between the average value and the maximum value, and 2.0°C between the average value and the minimum value. There was a difference of 1.0°C between As described above, in the comparative example, especially in the transitional period after the opening degree of the bypass valve 34 is changed, the deviation of the hot water supply temperature from the hot water supply set temperature was remarkable.

In the example, as shown in FIG. When the opening degree of the bypass valve 34 is controlled so as to decrease the opening degree of the bypass valve 34 due to the decrease in the temperature of the hot water supply, almost no increase or decrease in the temperature of the hot water supply is observed. It was confirmed that the temperature was kept constant and stable. This proves that the timing of controlling the degree of opening of the bypass valve 34 is timely.

The hot water supply temperature in the example was 40.2°C as the maximum value, 39.1°C as the minimum value, and 39.6°C as the average value. That is, the average value of the hot water supply temperature has a deviation (temperature difference) of 0.4°C from the hot water supply set temperature of 40°C, the difference between the average value and the maximum value is 0.6°C, and the average value and the minimum value are 0.6°C. Although there is a difference of 0.5° C. between the temperature and the hot water supply temperature, the temperature difference between the hot water supply temperature and the hot water supply set temperature was extremely small compared to the comparative example. As described above, it can be seen that in the example, the temperature deviation observed between the hot water supply temperature and the hot water supply set temperature as in the comparative example is eliminated in the transitional period after the opening degree of the bypass valve 34 is changed.

From the results of the above examples and comparative examples, according to the present invention, even when the temperature is adjusted while the burner 12 alternately repeats ignition and extinguishing, and a small amount of hot water is required. Also, the effect of increasing the stability of the hot water supply temperature was demonstrated.

It should be noted that the present invention is not limited to the above embodiments, and can be modified in various ways within the scope of the claims. For example, the present invention may be practiced under burner combustion conditions in which the burner alternately ignites and extinguishes and when a low water quantity hot water supply request is made.

1 Hot water supply device 10 Combustion device 11 Heat exchanger 12 Burner 13 Gas passage 14 Gas proportional valve 15 Combustion fan 20 Water supply passage 21 Hot water supply passage 22 Bypass passage 23 Hot water supply passage 24 Hot water supply valve 25 Bypass junction 30 Flow sensor 31 Water supply temperature sensor 32 Heat Discharged hot water temperature sensor 33 Hot water supply temperature sensor 34 Bypass valve 50 Control unit 51 Remote controller

Claims (3)

A heat exchanger heated by a burner, a water supply passage for supplying water to the heat exchanger, a hot water outlet passage connected to the heat exchanger for outflow of hot water produced by the heat exchanger, and a short circuit between the water supply passage and the hot water outlet passage. a bypass valve that increases or decreases the flow rate of water passing through the bypass passage; A heat exchanger output hot water temperature sensor that detects in the hot water outlet passage upstream of the bypass junction where the passage joins, and a heat exchanger communication from the hot water outlet passage in the bypass confluence so that hot water with a set hot water supply temperature can be obtained. A hot water supply apparatus comprising: a control unit that determines a bypass ratio, which is a mixing ratio of a water volume and a bypass water flow volume from a bypass passage, and controls an opening degree of a bypass valve,
The control unit
The heat-exchanged hot water temperature is used to determine the bypass ratio, and the heat-exchanged hot water temperature used for determining the bypass ratio is the current heat-exchanged hot water temperature detected by the heat-exchanged hot water temperature sensor. Instead, it is possible to replace the previously detected heat-exchanged hot water temperature with the relative heat-exchanged hot water temperature,
The relative heat-exchanged hot water temperature is the past heat-exchanged hot water temperature that goes back from the present to the past by the time required for the hot water flowing through the hot water outlet passage to reach the bypass junction from the position of the heat-exchanged hot water temperature sensor. hot water supply device. In the water heater according to claim 1,
The control unit
continuously storing the temperature of the heat-exchanged hot water detected by the heat-exchanged hot water temperature sensor as a stored value at regular time intervals;
calculating the retrogression time from the ratio of the current heat exchanger water flow rate to the volume of the hot water outlet passage from the position of the heat exchange hot water temperature sensor to the position of the bypass junction;
A hot water supply apparatus comprising a configuration for calculating the bypass ratio using a stored value of a heat exchange outlet hot water temperature before the retroactive time from the present as the relative heat exchange outlet hot water temperature. The water heater according to claim 1 or 2,
The control unit
The operation of determining the bypass ratio using the relative heat exchange output hot water temperature and controlling the opening degree of the bypass valve is executed when the temperature is adjusted while the burner alternately repeats ignition and extinguishing. Device.

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