JP2011149605A - Water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water heater detecting failure of a water temperature sensor without limiting a user's use of hot water. <P>SOLUTION: The water heater includes a mixing valve mixing water from a water supply pipe with hot water from a hot water supply pipe to produce mixed water. Based on a water supply temperature TW detected by a water supply temperature sensor, a hot water supply temperature TH detected by a hot water supply temperature sensor and a target mixed water temperature Tg set by the user, an upper limit opening SU and a lower limit opening SL of an opening of the mixing valve for making a mixed water temperature correspond to the target mixed water temperature Tg for the purpose of calculation are calculated. A temperature control means calculates a control mixing valve opening Sc based on a deviation between the target mixed water temperature Tg and a mixed water temperature Ta detected by a mixed water temperature sensor. When the control mixing valve opening Sc is deviated from a range from the upper limit opening SU to the lower limit opening SL, it is determined that any one of the water supply temperature sensor, the hot water supply temperature sensor and the mixed water temperature sensor is abnormal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a water heater.

  Conventionally, in a water heater, high temperature hot water heated by a heat source and low temperature water from the water source are mixed by an electric hot water mixing valve, and the temperature of the mixed water is detected by a mixed water temperature sensor. By adjusting the valve opening of the electric hot water mixing valve so that the detected mixed water temperature becomes the temperature set by the user, it is possible to supply hot water of the temperature desired by the user to the hot water tap .

  Patent Document 1 listed below discloses a technique for detecting a failure of a mixed water temperature sensor ("hot water supply temperature detection sensor" in Patent Document 1). In the water heater described in Patent Document 1, hot water is supplied with the mixing valve opening fully opened, and when the temperature detected by the mixed water temperature sensor indicates a predetermined temperature (55 ° C.) or lower, the mixed water temperature sensor Judged as a failure.

Japanese Patent Laid-Open No. 2004-20021

  As described above, in the water heater described in Patent Document 1, since it is necessary to forcibly open the hot water side in order to determine the failure of the mixed water temperature sensor, it is used until the failure determination ends. There is a problem that hot water cannot be supplied at the temperature desired by the person. Further, when the mixing valve opening is fully opened in the failure determination, hot water that is not mixed with water is supplied to the hot water tap, and the user may be burned.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a water heater that can detect a failure of a water temperature sensor without restricting the use of hot water to a user. And

  A water heater according to the present invention includes a water supply pipe that supplies water from a water source, a water temperature sensor that detects the temperature of water supplied from the water supply pipe, a hot water supply pipe that supplies hot water, and hot water supplied from the hot water supply pipe. A hot water temperature sensor for detecting the temperature of the water, a mixing valve for mixing the water supplied from the water supply pipe and the hot water supplied from the hot water supply pipe, the mixing ratio of the two being variable, and the opening of the mixing valve The temperature of the mixed water flowing downstream of the mixing valve and the actuator that can change the degree of water between the water side fully open where the water mixing ratio is maximum and the hot water side full opening where the hot water mixing ratio is the maximum Based on the deviation between the detected mixed water temperature sensor, the target mixed water temperature set by the user, and the temperature detected by the mixed water temperature sensor, temperature control means for calculating the mixing valve opening so as to eliminate the deviation, The temperature detected by the water temperature sensor and the hot water temperature sensor Based on the detected temperature and the target mixed water temperature, the calculated mixed valve opening, which is the mixed valve opening that is predicted to be the same as the target mixed water temperature in the calculation, allows for an error in the water side fully open direction. Means for calculating a first limit opening that is a shifted mixing valve opening, and a second limit opening that is a mixing valve opening that shifts the calculated mixing valve opening in anticipation of an error in the hot water side full open direction; When the control mixing valve opening, which is the mixing valve opening calculated by the temperature control means, does not fall within the range from the first limit opening to the second limit opening, the feed water temperature sensor, the hot water temperature sensor, and the mixed water temperature Abnormality determination means for determining that any of the sensors is abnormal.

  According to the present invention, it is possible to detect a failure of the water temperature sensor without restricting the use of hot water to the user. In addition, there is no risk that the user will be burned.

It is the schematic which shows embodiment of the water heater of this invention. It is a block diagram which shows the control circuit structure of the hot water storage type water heater shown in FIG. It is a flowchart of water temperature sensor abnormality detection in Embodiment 1 of this invention. It is a flowchart of water temperature sensor abnormality detection in Embodiment 2 of this invention. It is a flowchart of water temperature sensor abnormality detection in Embodiment 3 of this invention. It is a flowchart of water temperature sensor abnormality detection in Embodiment 4 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a schematic view showing an embodiment of a water heater according to the present invention. The water heater 130 shown in the figure has a function of boiling low-temperature water such as city water into hot water using a heat source machine and supplying hot water to a desired location. The water heater 130 includes a heat pump unit 10, a tank unit 110, and a control device 120. Hereinafter, each component of the water heater 130 will be described.

  The heat pump unit 10 includes a compressor 1 that compresses refrigerant, a heat exchanger 3 for boiling, an expansion valve 5, an evaporator 7, and a refrigerant circulation pipe 9 that connects these in an annular shape in the unit case 2. And functions as a heat source machine.

  On the other hand, the tank unit 110 has a hot water storage tank 20, a water supply pipe 30, a hot water circulation pipe 40 and a hot water supply pipe 50.

  The hot water storage tank 20 is a stacked hot water storage tank that stores the low-temperature water supplied from the water supply pipe 30 and the hot water boiled by the heat pump unit 10. In the lower part of the hot water storage tank 20, a water inlet 20 a to which the water supply pipe 30 is connected and a water outlet 20 b to which the forward pipe 40 a of the hot water circulation pipe 40 is connected are provided. In the upper part of the hot water storage tank 20, a hot water inlet 20 c to which the return pipe 40 b of the hot water storage circulation line 40 is connected and a hot water outlet 20 d to which the hot water supply pipe 50 is connected are provided. The inside of the hot water storage tank 20 is always kept full with the low temperature water of the lower layer and the hot water of the upper layer.

  The water supply pipe 30 is a pipe that supplies low-temperature water such as city water to the hot water storage tank 20, the hot water supply pipe 50, and a predetermined hot water supply destination. The first water supply pipe section 30a, the second water supply pipe section 30b, and the water supply It has a pipe 30c and a pressure reducing valve (not shown). The first water supply pipe section 30 a connects a water source (not shown) such as a water supply and the water inlet 20 a of the hot water storage tank 20. The water supply pipe 30c branches from the first water supply pipe section 30a, and connects the first water supply pipe section 30a and an electric hot and cold water mixing valve 45 described later. The 2nd water supply pipe part 30b branches from the 1st water supply pipe part 30a, and connects this 1st water supply pipe part 30a and a predetermined hot-water supply destination. In the illustrated example, one hot water tap 160 is shown as an example of a hot water supply destination. The pressure reducing valve is provided on the downstream side of the branch point of the second water supply pipe part 30b in the first water supply pipe part 30a, and reduces the water source water pressure to be equal to or lower than a predetermined value. In FIG. 1, the flow direction of the low temperature water in the 1st water supply pipe part 30a is shown by the solid line arrow.

  The hot water storage circulation line 40 is a pipe that reaches the hot water inlet 20c of the hot water storage tank 20 from the water outlet 20b of the hot water storage tank 20 through the boiling heat exchanger 3 in the heat pump unit 10, and is a three-way valve. 33 and a hot water storage water pump 35 are provided with an outgoing pipe 40a, a return pipe 40b, and a bypass pipe 40c provided in this order. The forward pipe 40 a connects the water outlet 20 b and the boiling heat exchanger 3. The return pipe 40b connects the boiling heat exchanger 3 and the hot water inlet 20c. The bypass pipe 40c branches from the forward pipe 40a by a three-way valve 33 provided on the upstream side of the boiling heat exchanger 3 in the forward pipe 40a, and connects the forward pipe 40a and the return pipe 40b. During the freeze prevention operation, the water that flows from the hot water storage tank 20 into the forward pipe 40a flows through the boiling heat exchanger 3 and the return pipe 40b, and again through the bypass pipe 40c to the forward pipe 40a. In order to enable a boiling operation for boiling hot water by the boiling heat exchanger 3 and the antifreezing operation, a hot water storage water supply pump 35 is provided on the downstream side of the three-way valve 33 in the forward pipe 40a.

  The hot water supply pipe 50 mixes the hot water flowing from the hot water storage tank 20 through the hot water supply pipe 50a and the low temperature water from the water supply pipe 30c by the electric hot water mixing valve 45, and the mixed hot water (hereinafter referred to as “hot water”). This is a pipe that supplies “mixed water” to a predetermined hot water supply destination (hot water tap 160 in the illustrated example). The hot water supply line 50 includes an electric hot water mixing valve 45, a hot water supply pipe 50a, and a mixed hot water supply pipe 50b. The hot water supply pipe 50 a connects the hot water outlet 20 d of the hot water storage tank 20 and the electric hot water mixing valve 45. The mixed hot water supply pipe 50 b connects the electric hot water mixing valve 45 and the hot water tap 160. In FIG. 1, the outflow direction of the hot water from the hot water tap 160 is indicated by a dashed arrow.

  The electric hot / cold water mixing valve 45 includes a valve for adjusting the mixing ratio of hot water supplied from the hot water supply pipe 50a and water supplied from the water supply pipe 30c, and a mixing valve drive motor 45a as an actuator for driving the valve. I have. By controlling the mixing valve drive motor 45a, the opening degree of the electric hot / cold water mixing valve 45 (hereinafter referred to as “mixing valve opening degree”) is set to the water side fully open where the water mixing ratio becomes maximum, and the hot water mixing ratio. It can be changed between the hot water side fully opened. In the present embodiment, when the opening degree of the mixing valve is fully opened on the water side, the mixing ratio is water 100: hot water 0, and when it is fully opened, the mixing ratio is water 0: hot water 100. .

  The mixing valve drive motor 45a in this embodiment is a stepping motor. The opening of the mixing valve in this embodiment can be expressed by the number of steps of this stepping motor. In the following description, the operation range of the electric hot / cold water mixing valve 45 is 0 to 1000 steps of the mixing valve drive motor 45a, where 0 step corresponds to water side full open and 1000 step corresponds to hot water side full open.

  A hot water supply temperature sensor 102 is attached to the upper part of the hot water storage tank 20. According to the hot water supply temperature sensor 102, the temperature of the hot water flowing through the hot water supply pipe 50a can be detected. A water supply temperature sensor 101 is attached to the water supply pipe 30c. According to the water supply temperature sensor 101, the temperature of the low-temperature water flowing through the water supply pipe 30c can be detected. A mixed water temperature sensor 103 is attached to the mixed hot water supply pipe 50b. According to the mixed water temperature sensor 103, the temperature of the mixed water downstream of the electric hot / cold water mixing valve 45 can be detected.

  Among the above-described components constituting the tank unit 110, each of the water supply conduit 30, the hot water storage circulation conduit 40, and the hot water supply conduit 50 extends to the outside of the unit case 112, The remaining components are housed in the unit case 112.

  FIG. 2 is a block diagram showing a control circuit configuration of the hot water storage type water heater having the above configuration. The control device 120 includes a control device main body 120a disposed in the unit case 112 and a remote controller 120b disposed in a kitchen, a bathroom, or the like and connected to the control device main body 120a by wire or wirelessly. The heat pump unit 10, the three-way valve 33, the mixing valve drive motor 45a, the feed water temperature sensor 101, the hot water temperature sensor 102, and the mixed water temperature sensor 103 are connected to the control device main body 120a. The control device main body 120a controls the operation of each unit based on information and commands input by the user from the remote controller 120b as an input device, signals from each sensor, and the like.

  Accordingly, the water heater 130 operates based on the above-described information and commands input by the user from the remote controller 120b. For example, when the boiling start time input by the user from the remote controller 120b is reached, the heat pump unit 10 and the hot water storage water supply pump 35 are activated under the control of the control device 120, and the boiling operation is started. The boiling operation is continued until it is determined from a detection result of a temperature sensor (not shown) provided in the hot water storage tank 20 that a predetermined amount of hot water is stored in the hot water storage tank 20. During this time, low-temperature water flows from the water outlet 20b at the lower part of the hot water storage tank 20 into the hot water circulation circuit 40, is heated to hot water by the heat pump unit 10, and is supplied to the hot water storage tank 20 from the hot water inlet 20c at the upper part of the hot water storage tank 20. Returned.

  The remote controller 120b is configured so that the temperature of hot water (mixed water) supplied to the hot water tap 160 can be set to an arbitrary temperature desired by the user. When the hot water tap 160 is opened, the control device main body 120a deviates between the hot water supply temperature set by the user with the remote controller 120b (hereinafter referred to as “target mixed water temperature”) and the temperature detected by the mixed water temperature sensor 103. The mixing valve drive motor 45a is controlled so that the mixing valve opening is controlled. That is, the controller main body 120a can perform feedback control of the mixed water temperature.

  FIG. 3 is a flowchart of a routine executed by the control device main body 120a in order to detect the water temperature sensor abnormality in the first embodiment of the present invention. Using this, the abnormality detection in the first embodiment will be described in detail.

  In step S1, the presence or absence of hot water supply is confirmed. Specifically, if hot water tap 160 is opened, it is determined that hot water is present, and the process proceeds to step S2. Otherwise it loops. In step S2, the feed water temperature TW detected by the feed water temperature sensor 101 is read, and the process proceeds to step S3. In step S3, hot water supply temperature TH detected by hot water supply temperature sensor 102 is read, and the process proceeds to step S4.

  In step S4, based on the water supply temperature TW acquired in step S2, the hot water supply temperature TH acquired in step S3, and the target mixed water temperature Tg previously set by the user with the remote control 120b, the mixing valve An upper limit opening and a lower limit opening are calculated.

As described above, the opening degree of the mixing valve is represented by 0 step (water side full open) to 1000 step (hot water side full open) of the mixing valve drive motor 45a. When the mixing valve opening is 0 step (water side full open), the water from the water supply pipe 30c flows directly to the mixed hot water supply pipe 50b, so the temperature detected by the mixed water temperature sensor 103 matches the water supply temperature TW. When the mixing valve opening is 1000 steps (fully open on the hot water side), the hot water from the hot water supply pipe 50a flows directly into the mixed hot water supply pipe 50b, so that the temperature detected by the mixed water temperature sensor 103 matches the hot water supply temperature TH. Therefore, the number of steps required to change the mixed water temperature detected by the mixed water temperature sensor 103 once when the mixing valve opening degree is moved by the mixing valve drive motor 45a is represented by 1000 / (TH-TW). be able to. Accordingly, when the opening degree of the mixing valve predicted by calculation when the temperature detected by the mixed water temperature sensor 103 matches the target mixed water temperature Tg, Se is expressed by the following equation.
Se = 1000 / (TH−TW) × (Tg−TW) (1)

Hereinafter, the mixing valve opening degree Se represented by the above equation (1) is referred to as “calculated mixing valve opening degree”. In step S4, the upper limit opening degree SU and the lower limit opening degree SL are calculated assuming that an error of a width corresponding to ± 5 degrees at the target mixed water temperature is a normal range with respect to the calculated mixing valve opening degree Se. That is, the upper limit opening degree SU and the lower limit opening degree SL are respectively expressed by the following equations.
SU = 1000 / (TH−TW) × (Tg + 5−TW) (2)
SL = 1000 / (TH−TW) × (Tg−5−TW) (3)

  In step S4, the upper limit opening degree SU and the lower limit opening degree SL are calculated according to the above equations (2) and (3), and the process proceeds to step S5. Note that the upper limit opening degree SU calculated by the above equation (2) is a value obtained by shifting the calculated mixing valve opening degree Se in the hot water side full open direction by allowing for an error of a width exceeding the target mixed water temperature by 5 degrees (second limit). The lower limit opening degree SL calculated by the above formula (3) is calculated by taking the calculated mixing valve opening degree Se into the water side fully open direction by allowing for an error of 5 degrees below the target mixed water temperature. This corresponds to the shifted value (first limit opening).

  In step S5, the mixed water temperature Ta detected by the mixed water temperature sensor 103 is read, and the process proceeds to step S6. In step S6, based on the deviation between the target mixed water temperature Tg and the mixed water temperature Ta detected by the mixed water temperature sensor 103, the mixing valve opening degree obtained by performing feedback correction processing in a direction to eliminate the deviation is calculated. The mixing valve opening calculated in step S6 is hereinafter referred to as “control mixing valve opening” and is represented by the symbol Sc. After step S6, the process proceeds to step S7.

  In step S7, it is compared whether the control mixing valve opening degree Sc calculated in step S6 is in a range from the upper limit opening degree SU to the lower limit opening degree SL. When the control mixing valve opening degree Sc is in the range from the upper limit opening degree SU to the lower limit opening degree SL, the control mixing valve opening degree Sc calculated based on the detected value of the mixed water temperature sensor 103 and the water supply temperature Since it can be determined that the deviation from the calculated mixing valve opening degree Se calculated based on the detection values of the sensor 101 and the hot water temperature sensor 102 is within the normal range, the hot water temperature sensor 101, the hot water temperature sensor 102, and the mixed water temperature sensor 103 Are determined to be normal. In this case, the process proceeds to step S8, and the mixing valve drive motor 45a is controlled so that the actual mixing valve opening degree coincides with the control mixing valve opening degree Sc.

  On the other hand, if the control mixing valve opening Sc is not in the range from the upper limit opening SU to the lower limit opening SL in step S7, the control mixing valve opening Sc and the calculated mixing valve opening Se It can be judged that the deviation is larger than the normal range. For this reason, in this case, it is determined that any of the feed water temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103 is abnormal, and the process proceeds to step S10.

  In step S10, the control mixing valve opening Sc is compared with the lower limit opening SL. When the control mixing valve opening degree Sc is smaller than the lower limit opening degree SL, that is, when the control mixing valve opening degree Sc is in the range of the water side fully open direction from the lower limit opening degree SL, the process proceeds to step S11. In step S11, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening coincides with the lower limit opening SL.

  On the other hand, when the control mixing valve opening degree Sc is not smaller than the lower limit opening degree SL in step S10, the control mixing valve opening degree Sc is larger than the upper limit opening degree SU. That is, the control mixing valve opening Sc is in the range of the hot water side fully open direction from the upper limit opening SU. In this case, the process proceeds to step S12. In step S12, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening degree coincides with the upper limit opening degree SU.

  According to the first embodiment described above, the temperature of the mixing valve is not forced to be fully opened for detecting the water temperature sensor abnormality, and the water temperature sensor is supplied while supplying hot water at the hot water temperature set by the user. Anomaly detection can be performed. For this reason, use of hot water is not restricted to the user. Further, since the opening of the mixing valve is not forced to be fully opened on the hot water side, there is no risk of burns and the safety of the user can be ensured.

  Furthermore, according to the present embodiment, when it is determined that any of the water supply temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103 is abnormal, the control mixing valve opening Sc is less than the lower limit opening SL. When it is in the range of the water side fully open direction, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening coincides with the lower limit opening SL, and the control mixing valve opening Sc is higher than the upper opening SU. When in the range of the side fully open direction, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening degree coincides with the upper limit opening degree SU. As a result, even when an abnormality occurs in any of the water temperature sensor 101, the hot water temperature sensor 102, and the mixed water temperature sensor 103, hot water at a temperature that is as close as possible to the hot water temperature set by the user and that is not dangerous is the hot water tap 160. Therefore, usability can be improved while ensuring safety.

  In the present embodiment, when the control mixing valve opening Sc is not within the range from the upper limit opening SU to the lower limit opening SL, any one of the water supply temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103 is selected. In this case, it may be determined that the mixed water temperature sensor 103 is abnormal.

Embodiment 2. FIG.
FIG. 4 is a flowchart of water temperature sensor abnormality detection in the second embodiment of the present invention. Embodiment 2 of the present invention will be described using this. However, since the configuration of the water heater is the same as that of Embodiment 1, the description thereof is omitted. Further, since the operation flow from step S1 to step S8 is the same as that of the first embodiment, the same reference numerals are given and description thereof is omitted.

  When the control mixing valve opening Sc is not in the range from the upper limit opening SU to the lower limit opening SL in step S7 of FIG. 4, that is, the water supply temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103. If it is determined that there is an abnormality in any one, the process proceeds to step S13.

In step S13, the control mixing valve opening degree Sc and the calculated mixing valve opening degree Se are compared. The calculated mixing valve opening degree Se can be calculated based on the equation (1). Alternatively, it can be calculated as follows. The following expression is established from the expressions (1) to (3).
Se = (SU + SL) / 2 (4)
Therefore, the calculated mixing valve opening degree Se may be calculated by substituting the values of the upper limit opening degree SU and the lower limit opening degree SL calculated in step S4 into the above equation (4).

  If the control mixing valve opening Sc is smaller than the calculated mixing valve opening Se in step S13, the process proceeds to step S14. In step S14, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening degree coincides with the control mixing valve opening degree Sc.

  On the other hand, if the control mixing valve opening Sc is not smaller than the calculated mixing valve opening Se in step S13, that is, if the control mixing valve opening Sc is greater than or equal to the calculated mixing valve opening Se, step S15 is performed. Proceed to In step S15, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening degree coincides with the calculated mixing valve opening degree Se.

  According to the present embodiment described above, similarly to the first embodiment, the abnormality of the water temperature sensor can be detected without restricting the use of hot water by the user and without causing the user to be burned.

  Further, according to the present embodiment, when it is determined that any of the feed water temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103 is abnormal, the control mixing valve opening Sc and the calculated mixing valve opening The mixing valve drive motor 45a is controlled so that the actual opening of the mixing valve coincides with the smaller opening of Se (that is, the opening close to the water side fully open). As a result, when an abnormality occurs in any of the feed water temperature sensor 101, the hot water temperature sensor 102, and the mixed water temperature sensor 103, the mixed water temperature becomes lower among the control mixing valve opening Sc and the calculated mixing valve opening Se. Hot water and water are mixed at the opening of the mixing valve. Therefore, even when it is determined that there is an abnormality in either the hot water temperature sensor 102 or the mixed water temperature sensor 103, hot water having a temperature that is as close as possible to the hot water temperature set by the user and that is not dangerous is supplied to the hot water tap 160. Therefore, usability can be improved while ensuring safety.

Embodiment 3 FIG.
FIG. 5 is a flowchart of water temperature sensor abnormality detection in the third embodiment of the present invention. Embodiment 3 of the present invention will be described in detail using this. However, since the configuration of the water heater is the same as that of Embodiment 1, the description thereof is omitted. Further, since the operation flow from step S1 to step S8 is the same as that of the first embodiment, the same reference numerals are given and description thereof is omitted.

  When the control mixing valve opening Sc is not in the range from the upper limit opening SU to the lower limit opening SL in step S7 in FIG. 5, that is, the water supply temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103. If it is determined that there is an abnormality in any one, the process proceeds to step S16.

  In step S16, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening degree coincides with a predetermined fixed value Sa. The fixed value Sa is a mixing valve opening degree that can guarantee that the temperature of the hot water coming out of the hot water tap 160 does not become a dangerous temperature. For example, when the lowest temperature hot water (for example, 65 ° C.) out of the hot water supply temperature range from the hot water supply pipe 50a and the water at the highest predicted temperature in the water supply temperature range from the water supply tube 30c (for example, 24 ° C.) are mixed. The mixing valve opening calculated when the mixed water temperature becomes an appropriate temperature (for example, 30 ° C.) may be set to the fixed value Sa. That is, in this example, a value calculated by substituting TH = 65 ° C., TW = 24 ° C., and Tg = 30 ° C. into the equation (1) may be set in advance as the fixed value Sa. If the actual mixing valve opening is such a fixed value Sa, the hot water supply temperature from the hot water supply pipe 50a and the hot water supply temperature from the water supply pipe 30c are supplied to the hot water tap 160 regardless of the conditions. The temperature of the mixed water is in an appropriate temperature range that does not cause burns and is not too cold.

  According to the present embodiment described above, similarly to the first embodiment, the abnormality of the water temperature sensor can be detected without restricting the use of hot water by the user and without causing the user to be burned.

  Further, according to the present embodiment, when it is determined that any one of the feed water temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103 is abnormal, the actual mixing valve opening is determined in advance. The mixing valve drive motor 45a is controlled so as to coincide with an appropriate fixed value Sa. Thus, even when it is determined that there is an abnormality in either the hot water temperature sensor 102 or the mixed water temperature sensor 103, hot water having an appropriate temperature that is not too cold and is not too cold is supplied to the hot water tap 160. Therefore, usability can be improved while ensuring safety.

Embodiment 4 FIG.
FIG. 6 is a flowchart of water temperature sensor abnormality detection in the third embodiment of the present invention. Embodiment 4 of the present invention will be described in detail using this. However, since the configuration of the water heater is the same as that of Embodiment 1, the description thereof is omitted. Further, since the operation flow from step S1 to step S8 is the same as that of the first embodiment, the same reference numerals are given and description thereof is omitted.

  When the control mixing valve opening Sc is not in the range from the upper limit opening SU to the lower limit opening SL in step S7 in FIG. 6, that is, the water supply temperature sensor 101, the hot water supply temperature sensor 102, and the mixed water temperature sensor 103. If it is determined that there is an abnormality in any one, the process proceeds to step S17. In step S17, the mixing valve drive motor 45a is controlled so that the actual mixing valve opening is fully opened on the water side (water 100: hot water 0).

  According to the present embodiment described above, similarly to the first embodiment, the abnormality of the water temperature sensor can be detected without restricting the use of hot water by the user and without causing the user to be burned.

  Further, according to the present embodiment, when it is determined that any of the feed water temperature sensor 101, the hot water temperature sensor 102, and the mixed water temperature sensor 103 is abnormal, the actual mixing valve opening is fully opened on the water side. The As a result, when it is determined that there is an abnormality in either the hot water temperature sensor 102 or the mixed water temperature sensor 103, the water from the water supply pipe 30c is supplied to the hot water tap 160 as it is, and the user is burned. Can be prevented more reliably.

DESCRIPTION OF SYMBOLS 10 Heat pump unit 20 Hot water storage tank 30c Water supply pipe 45 Electric hot water mixing valve 45a Mixing valve drive motor 50a Hot water supply pipe 50b Mixed hot water supply pipe 101 Hot water temperature sensor 102 Hot water temperature sensor 103 Mixed water temperature sensor 120 Control apparatus 120a Control apparatus main body 120b Remote control 160 Hot water tap

Claims (6)

A water supply pipe for supplying water from a water source;
A feed water temperature sensor for detecting the temperature of water supplied from the feed pipe;
A hot water supply pipe for supplying hot water;
A hot water temperature sensor for detecting the temperature of hot water supplied from the hot water pipe;
A mixing valve provided at a location where water supplied from the water supply pipe and hot water supplied from the hot water supply pipe are mixed, and the mixing ratio of the two is variable;
An actuator capable of changing the opening of the mixing valve between a water side fully open where the mixing ratio of the water is maximum and a hot water side fully open where the mixing ratio of the hot water is maximum;
A mixed water temperature sensor for detecting the temperature of the mixed water flowing downstream of the mixing valve;
Based on the deviation between the target mixed water temperature set by the user and the temperature detected by the mixed water temperature sensor, temperature control means for calculating the mixing valve opening so as to eliminate the deviation;
Based on the temperature detected by the feed water temperature sensor, the temperature detected by the hot water supply temperature sensor, and the target mixed water temperature, the mixing valve is predicted to be the same as the target mixed water temperature in calculation. The first limit opening, which is a mixing valve opening that is shifted in consideration of an error in the water side fully open direction, and the calculated mixing valve opening, which is an opening, and the error in the calculated mixing valve opening in the hot water side fully open direction Means for calculating a second limit opening which is a shifted mixing valve opening;
When the control mixing valve opening that is the mixing valve opening calculated by the temperature control means does not fall within the range from the first limit opening to the second limit opening, the water supply temperature sensor, the hot water supply An abnormality determining means for determining that there is an abnormality in either the temperature sensor or the mixed water temperature sensor;
A water heater characterized by comprising.   The abnormality determining means determines that the mixed water temperature sensor is abnormal when the control mixing valve opening does not fall within a range from the first limit opening to the second limit opening. The water heater according to claim 1. Means for causing the actual mixing valve opening to coincide with the first limit opening when the control mixing valve opening is in the range of the water side fully open direction relative to the first limit opening;
Means for causing the actual mixing valve opening to coincide with the second limit opening when the control mixing valve opening is in the range of the hot water side fully open direction relative to the second limit opening;
The water heater according to claim 1 or 2, further comprising:   Means for causing the actual mixing valve opening to coincide with the opening of the control mixing valve opening and the calculated mixing valve opening that is closer to the water side fully open when the abnormality determining means determines that there is an abnormality. The water heater according to claim 1 or 2, further comprising:   3. The water heater according to claim 1, further comprising means for causing an actual mixing valve opening to coincide with a predetermined fixed value when the abnormality determination means determines that there is an abnormality.   The hot water heater according to claim 1 or 2, further comprising means for causing the actual mixing valve opening to be fully opened when the abnormality determination means determines that there is an abnormality.

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