JP3834415B2 - Water heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water heater having a heat retaining function for burning a burner in a state where there is no water flow so as to keep water in a heat exchanger in the next hot water and keep it within a predetermined heat retaining temperature range.
[0002]
[Prior art]
Conventionally used hot water heaters have a function to keep hot water in the heat exchanger within a specified temperature range without passing water in order to discharge hot water as close to the set temperature as possible from the beginning of opening. There is something. In such a water heater, normally, the heat insulation state is maintained from when the water flow is stopped until a certain time such as 5 minutes elapses.
[0003]
[Problems to be solved by the invention]
However, in such a conventional technique, when the hot water is discharged after a certain period of time such as 5 minutes has passed since the previous hot water, since it is not already in a heat retaining state, the cold temperature greatly deviated from the set temperature at the time of opening. Hot water comes out. For example, when a long time has passed since the last bathing, when the shower started to be used in the bathroom, there was a problem that cold water started out and caused discomfort.
[0004]
The present invention has been made paying attention to such problems of the prior art, and burners are burned in a state where there is no water flow so that the water in the heat exchanger is prepared for the next hot water and is kept at a predetermined temperature. An object of the present invention is to provide a water heater that can be turned on / off at an appropriate timing in preparation for the use of a shower with a heat retaining function for keeping heat within a temperature range.
[0005]
[Means for Solving the Problems]
The gist of the present invention for achieving the object lies in the inventions of the following items.
[1] In a water heater having a heat retaining function that burns the burner (12) in a state where there is no water flow and keeps the water in the heat exchanger (13) within a predetermined heat retaining temperature range in preparation for the next hot water. ,
As a basis for determining whether or not to start the warming operation, a warming control means (51) for controlling the warming operation for performing the warming function, an operation receiving unit (60) for receiving various operations And a sensor (37, 72, 73, 74) for detecting a predetermined state,
The heat retention control means (51) is configured to take a shower when the set state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) have a predetermined combination . A hot water heater characterized by determining a time zone to be used and starting the heat retaining operation according to the determination result .
[0006]
[2] The heat retention control means (51) has a predetermined period after the set state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) are combined. The hot water heater according to [1], wherein the warming operation is started when a lapse of time.
[0007]
[3] The heat retention control means (51) is configured so that a predetermined time after the set state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) are combined. The water heater according to [1], wherein the heat retaining operation is stopped when a lapse of time.
[0008]
[4] In a water heater having a heat retaining function that burns the burner (12) in a state where there is no water flow and keeps the water in the heat exchanger (13) within a predetermined heat retaining temperature range in preparation for the next hot water. ,
As a basis for determining whether or not to start the warming operation, a warming control means (51) for controlling the warming operation for performing the warming function, an operation receiving unit (60) for receiving various operations And a sensor (37, 72, 73, 74) for detecting a predetermined state,
The heat retention control means (51) is configured to take a shower when the set state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) have a predetermined combination . A hot water heater characterized by determining a time period to be used and stopping the heat retaining operation according to the determination result .
[0009]
[5] The heat retention control means (51) has a predetermined time after the set state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) are combined. The hot water heater as set forth in [4], wherein when the time has elapsed, the heat retaining operation is stopped.
[0010]
The present invention operates as follows.
Controls the heat retention operation to burn the burner (12) in the absence of water flow and to carry out the heat retaining function to keep the water in the heat exchanger (13) within the predetermined heat retaining temperature range in preparation for the next hot water. The thermal insulation control means (51) to be used is used for the shower when the set state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) have a predetermined combination. The warming operation is started or stopped according to the determination result .
[0011]
For example, when the automatic operation switch is turned on and the human sensor (72) arranged in the bathroom detects that a person is present in the bathroom, the heat retaining function is turned on. On the other hand, when the automatic operation switch is off, even if it is detected that a person has entered the bathroom, the warming function is not turned on and the operation is stopped. As a result, when a person enters the bathroom for cleaning, the heat retention function can be prevented from operating, and the heat retention function is turned on only when it is really needed, saving energy. Can be achieved.
[0012]
In addition, even when the bath operation switch is off, when the water level sensor (37) detects that a person has entered the bathtub, it is possible to use a shower at the washing place afterwards. Turn on.
[0013]
In this way, the time zone in which the shower is used is determined when the setting state from the operation receiving unit (60) and the detection state of the sensors (37, 72, 73, 74) have a predetermined combination. However, by turning the heat retention function on or off according to the determination result, the heat retention function can be turned on and off more finely than in the case where it is based on only one of the setting by operation and the sensor (37, 72, 73, 74). Can be controlled.
[0014]
The heat retention control means (51) has passed a predetermined time or period since the setting state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) have a predetermined combination. When the warming operation starts or stops. For example, since a shower is usually used in a washing place for several tens of minutes after a person leaves the bathtub, the heat retaining function is turned off after a predetermined time after detecting that the person has left the bathtub. In addition, when there is a person in the bathroom and the urine switch for pouring water into the bathtub and lowering the hot water temperature by about 2 ° C is pressed, the operation of pouring the water is finished (corresponding to the passage of a predetermined period) And turn on the heat retention function.
[0015]
As described above, after the set state based on the operation and the output state of the sensors (37, 72, 73, 74) have a predetermined combination, the heat retaining function is turned on / off after a predetermined time or a predetermined period has elapsed. Thus, the degree of freedom of control is widened, and the start and stop of the heat retaining operation can be controlled at the optimum timing.
[0016]
In addition, when the predetermined time has elapsed after the set state from the operation receiving unit (60) and the output state of the sensors (37, 72, 73, 74) have become a predetermined combination, the heat retention control means (51) The heat retaining operation may be stopped.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Each figure shows an embodiment of the present invention.
A water heater 10 according to the present invention has a function of supplying hot water into a faucet or a bath tub and a function of chasing hot water in the tub, and both the reheating path and the hot water supply path are provided by one heat exchanger. It is a so-called 1 can 2 water channel type that heats. As shown in FIG. 1, the water heater 10 includes a combustion chamber 11, a burner 12 is provided at the lower part of the combustion chamber 11, and heat from the burner 12 is provided at the upper part of the combustion chamber 11 for supplying water or the like. A heat exchanger 13 for transmitting is arranged.
[0018]
Both the hot water supply pipe 21 for flowing hot water and the recirculation pipe 31 for circulating water in the bathtub for reheating pass through the heat exchanger 13. The heat from the burner 12 is transmitted to the fluid in both the pipes 21 and 31 and heated.
[0019]
Between the hot water supply pipe 21, a water supply side flow path 21 a connected to the inlet side of the heat exchanger 13 and a hot water supply side flow path 21 b extending from the outlet side of the heat exchanger 13, a fixed bypass path 22 and a flow rate are provided. Two bypass paths of the bypass path 24 in which the control valve 23 is inserted are connected. The hot water heated by the heat exchanger 13 is mixed with the feed water through the fixed bypass passage 22 and the bypass passage 24, and the bypass ratio can be controlled by the flow control valve 23. In addition, a flow rate control valve 25 for controlling the total flow rate of the hot water and the bypass ratio is provided on the hot water supply side channel 21b side of the hot water supply pipe 21.
[0020]
Flow sensors 26a and 26b for detecting the presence / absence of water flow and the amount of water flow are provided in the vicinity of the inlet and outlet of the hot water supply pipe 21, respectively. In addition, an incoming water thermistor 27 for detecting the temperature of the hot water supply is attached in the vicinity of the inlet portion of the hot water supply pipe 21, and an outlet hot water thermistor 28 for detecting the temperature of the hot water supply is attached in the vicinity of the outlet portion of the hot water supply pipe 21. It has been. Further, a hot water thermistor 29 for detecting the hot water temperature immediately after leaving the heat exchanger 13 is provided in the hot water side channel 21b near the outlet of the heat exchanger 13.
[0021]
The circulation pipe 31 for reheating is composed of a bath return pipe portion 31a for returning water in the bathtub 40 to the heat exchanger 13 and a bath return pipe portion 31b for sending hot water heated by the heat exchanger 13 to the bathtub 40. ing. In the middle of the bath return pipe portion 31a, a circulation pump 32 and a bath running water switch 33 for detecting the presence or absence of water flow in the bath return pipe portion 31a are provided. A bath temperature thermistor 34 for detecting the temperature of hot water flowing from the bathtub 40 side is attached in the vicinity of the bath water switch 33. Further, a water level sensor 37 for detecting the water level (water pressure) in the bathtub 40 is disposed in the vicinity of the bath temperature thermistor 34.
[0022]
The hot water supply side pipe 21b of the hot water supply pipe 21 and the bath return pipe portion 31a are connected by a pouring pipe 36 having a pouring solenoid valve 35, and the hot water supplied by the heat exchanger 13 is poured. Hot water can be poured into the bathtub 40 through the pipe 36.
[0023]
The supply / exhaust is forcibly performed by blowing the supply air from the lower side of the combustion chamber 11 by the combustion fan 14, and the exhaust is discharged from the upper part of the combustion chamber 11. An ignition device 15 is provided in the vicinity of the burner 12. The combustion gas supplied to the burner 12 is on / off controlled by the gas solenoid valve 16, the original gas solenoid valve 17, and the gas switching valve 18. Further, the amount of combustion gas supplied to the burner 12 is adjusted by a gas proportional valve 19.
[0024]
The water heater 10 has a control base 50 for comprehensively controlling various operations such as hot water supply or filling a bath. The control board 50 includes a heat retention control unit 51, a normal combustion control unit 52, and a communication unit 53. Among these, the heat retaining control unit 51 controls an operation (heat retaining operation for hot water) for igniting the burner 12 and maintaining the hot water in the heat exchanger 13 within a predetermined temperature range without passing water. It is a circuit part. The normal combustion control unit 52 is a circuit part that controls the combustion of the burner 12 when the hot water is discharged according to the water flow, or when the hot water is poured or refilled. The communication unit 53 is a circuit part for receiving a remote operation through the telephone line 71, and implements so-called telecontrol.
[0025]
More specifically, the control board 50 executes a central processing unit (CPU) that performs a central function of various controls, a ROM that stores programs executed by the CPU and various fixed data, and programs. It is constituted by a circuit having a RAM or the like for storing temporarily necessary data as a main part.
[0026]
Connected to the control board 50 is a remote control unit 60 including an operation unit 61 for accepting various operations such as setting of hot water temperature and on / off of automatic operation and a display unit 62 including a liquid crystal display. In addition, the control board 50 has a human sensor 72 for detecting whether or not there is a person in the bathroom, an outside air temperature sensor 73 for detecting outside air temperature, and further for determining whether it is nighttime or daytime. An optical sensor 74 or the like is connected. In addition, various control components and sensors such as a water inlet thermistor 27, a water level sensor 37, a gas proportional valve 19, and a flow rate control valve 23 are connected to the control base 50 through a wiring 75.
[0027]
FIG. 2 shows the remote control unit 60. Various displays such as a set temperature display 62a and a combustion display 62b indicating that the burner 12 is burning are displayed on the display unit 62. In addition, the display unit 62 displays an error code or the like indicating the contents when an abnormality occurs. Below the display unit 62, various operation switches are arranged as the operation unit 61. Among these, the switch with the upward arrow symbol is an up switch 63a for increasing the set temperature, and the switch with the downward arrow symbol is a down switch 63b for decreasing the preset temperature.
[0028]
The priority switch 64a on which "priority" is written gives priority setting so that the temperature of the hot water discharged follows the temperature set on the own unit side when two or more remote control units such as a main remote controller and a bath remote controller are attached. It is a switch for. A priority lamp 64b disposed immediately above the priority switch 64a is a lamp for indicating that the own unit side is prioritized.
[0029]
The operation switch 65 on which the characters “operation” are written is for switching the hot water heater 10 between an operation state in which hot water can be poured out, filling the bathtub 40, reheating, etc., and a non-operation state in which these operations are not performed. It is a switch. The automatic switch 66 marked with “automatic” is a switch to be pressed when performing automatic bath operation. When the automatic switch 66 is pressed, the water heater 10 performs pouring and reheating so that the hot water at the set temperature is filled up to the set water level in the bathtub 40.
[0030]
The call switch 67 on which “call” is written is a switch for talking to a person in the kitchen from the bathroom or the like. That is, when the call switch 67 is pressed, a sound picked up by a microphone (not shown) arranged in the bath remote controller is played from a speaker (not shown) provided in the main remote controller installed in the kitchen or the like, and a person in the bathroom "towels""I want you to bring your own" message to people in the kitchen.
[0031]
The assembling switch 68a on which the letters “atsume” are written is a switch for raising the temperature of the hot water in the bathtub 40 by 2 ° C. from the current level. On the other hand, the ume switch 68b on which the characters “ume” are written is a switch used when the hot water temperature in the bathtub 40 is lowered by about 2 ° C. When the plumbing switch 68b is pressed, the hot water solenoid valve 35 is opened without igniting the burner 12, and unheated water is poured into the bathtub 40. The comfort switch 69 on which “Comfort” is written is a dedicated switch for turning on and off the heat retaining function.
[0032]
Next, the operation will be described.
While the heat retaining function is on, the heat retaining control unit 51 controls the combustion of the burner 12 so as to maintain the hot water in the heat exchanger 13 within a predetermined heat retaining temperature range. Here, when the hot water temperature in the heat exchanger 13 is lower than the lower limit value of the temperature keeping temperature range, the burner 12 is burned at a predetermined minimum combustion amount for about 2 seconds. Thereby, while the warming operation for hot water is operating (while the warming function is on), short combustion of about 2 seconds is intermittently performed. Moreover, the temperature keeping temperature range is set to a temperature considerably higher than the set temperature of the hot water, and the hot water temperature is lowered to the set temperature by adjusting the mixing amount of the water supply by the flow control valves 23 and 25, and the hot water is discharged. It is like that.
[0033]
When the set state from the remote control unit 60 and the detection results of various sensors such as the water level sensor 37, the human sensor 72, the outside air temperature sensor 73, and the light sensor 74 are in a predetermined combination, The heat retention function is turned on or off. Separately from this, the heat retention control unit 51 automatically turns on the heat retention function for 5 minutes after the previous hot water stop and keeps the hot water in the heat exchanger 13 ready for the next hot water. It is like that.
[0034]
FIG. 3 shows an example of the correspondence between the combination of the setting state based on the operation of the remote control unit 60 and the detection states of various sensors and the on / off control of the heat retaining function. In FIG. 3, the setting state 80a by operation is shown in the horizontal direction, and the detection state 80b of the sensor is shown in the vertical direction. In the figure, a circle indicates that the heat retaining function is turned on from off, and a cross indicates that the heat retaining function is turned on from off.
[0035]
Each setting state 80a is divided into a case where each switch of the remote control unit 60 is on and a case where it is off. The sensor detection state 80b is divided into environmental conditions such as a person entering and exiting the bathtub 40, a person entering and exiting the bathroom, and an outside temperature.
[0036]
The environment affirmation state 81 is a state in which the environment such as the outside air temperature or brightness affirms that the heat retaining function is turned on, that is, when the outside air temperature is equal to or lower than a certain temperature or when the light sensor 74 detects that it is night. It is in a state. The environment negative state 82 is a state in which the environment such as the outside air temperature or brightness denies turning on the heat retention function, that is, a state where the outside air temperature is higher than a predetermined value or the light sensor 74 detects that it is not night. It is.
[0037]
In FIG. 3, the heat insulation function is turned on when the setting state by each switch is on, and the heat insulation function is turned off when the setting state is off. An exception is set according to the detection state of the sensor. It is. For example, when the automatic operation of the bath by the automatic switch 66 is in the on state 83, basically, the thermal insulation function is turned on (marked with ○), but when the person is out of the bathroom 84, the shower is Judging that there is no possibility of use, the thermal insulation function is turned off. The same applies when the operation switch 65 is in the on state 85 or when the priority switch 64a is in the on state 86.
[0038]
When the automatic operation of the bath is in the off state 87, the heat retaining function is basically turned off. However, when the hot water temperature in the bathtub 40 is above a certain level, the bath may be bathed even if the automatic bath operation is off. Therefore, even when the automatic bathing operation is in the off state 87, when the water level sensor 37 detects that a person has entered the bathtub 40 (state 88), there is a possibility of using a shower or the like in a washing place. So the heat retention function is turned on.
[0039]
When the comfort switch 69 provided exclusively for the on / off of the heat retaining function is in the on state 91, the heat retaining function is turned on regardless of the detection state of various sensors in order to give priority to the user's will.
[0040]
On the other hand, when the environmental state such as the outside air temperature is in the environmental affirmation state 81 in which the heat insulation function is affirmed, the heat insulation function is turned on regardless of the setting state based on the operation of various switches. For example, even if the operation switch 65 or the automatic switch 66 is in an off state, there is a possibility of freezing or the like when the outside air temperature is low, so the heat retaining function is turned on to prevent this.
[0041]
In addition, when the setting state by operation and the detection state of the sensor become a predetermined combination, the heat retention function is immediately turned on, and it may be turned on after a predetermined time or a predetermined period has elapsed. For example, when the automatic operation of the bath is in the off state 87 and the heat retaining function is turned on based on the person entering the bathtub 40, the heat retaining function is immediately after the person leaves the bathtub 40. It is not turned off and is turned off after a predetermined time has passed after leaving the bathtub 40. This corresponds to the fact that a shower or the like may be used in a washing place for a while after leaving the bathtub 40.
[0042]
Further, when the urine switch 68b is turned on, unheated water is poured into the bathtub 40 through the hot water supply path in the heat exchanger 13, so that the burner 12 cannot be burned until the operation is completed. Can not. Therefore, when the ume switch 68b is turned on under the condition that there is a person in the bathroom, etc., the warming function is turned on after waiting for the ume operation to be completed.
[0043]
At the time when the operation for filling is completed, the hot water supply path side of the heat exchanger 13 is filled with low-temperature water. Therefore, when the heat insulation function is turned on, the burner 12 is burned with a predetermined heating power larger than the minimum combustion amount, and the hot water temperature is rapidly increased until it enters the heat insulation temperature range. Combustion for 2 seconds according to the amount of combustion is repeated intermittently).
[0044]
3 shows conditions for changing the heat retention function from off to on, or from on to off, and the heat retention function is turned on or off while this state continues. Is not maintained. As shown in FIG. 3, the heat retention function is turned off in accordance with the combination of the setting state by operation and the detection state of the sensor, and is turned off when a predetermined time has elapsed since the heat insulation function was turned on. Sometimes it is done.
[0045]
For example, when the hot switch 68a is pressed, there is a high possibility that there is a person in the bathroom, but the person who pressed the hot switch 68a usually leaves the bathroom within tens of minutes. Therefore, when the heat retaining function is turned on based on the depression of the hot switch 68a, the heat retaining function is stopped when a predetermined time has passed.
[0046]
Note that it is not necessary to validate all of the various combinations that determine the on / off of the above-described heat retaining function, and a combination used for on / off control of the heat retaining function can be selected as appropriate. For example, only the automatic bathing operation can be selected as the setting state by operation, and only the entrance and exit to the bathroom can be selected as the sensor state. In addition, it is possible to select two or more setting states and sensor states, such as automatic bath operation and operation of a dedicated switch.
[0047]
In the embodiment described above, a dedicated switch is provided for turning on and off the heat retaining function. However, a special operation different from the normal operation such as pressing the up switch 63a and the down switch 63b at the same time is turned on and off. May be set as a dedicated operation. In addition, timer setting may be provided as one of special operations. That is, the warming function may be turned on after completing the preparatory operation of waiting until the set time arrives based on the timer setting operation. In this case, when the time is up, the detection state of a predetermined sensor is searched, and when the combination is designated, the heat retaining function is turned on.
[0048]
Further, in the embodiment, various operations and various sensors for turning on and off the heat retaining function are provided, and an appropriate one can be selected and made effective from the combination thereof. It is not necessary to provide a sensor, and it may have only one or two or more operations and sensors. Moreover, the combination shown in FIG. 3 is an example, and is not limited to this.
[0049]
Furthermore, although the human sensor 72, the water level sensor 37, the outside air temperature sensor 73, the optical sensor 74, and the like are used as sensors for turning on and off the heat retaining function, other sensors may be used. In the embodiment, the infrared sensor is used as the human sensor 72. However, the present invention is not limited to this. For example, the entrance / exit into the bathroom may be detected by a door switch provided on the bathroom door. A switch linked to a bathroom lighting switch or the like may be used as the human sensor 72. In the embodiment, various operations are input from the remote control unit 60. However, instead of direct operations from the remote control unit 60, remote operations may be performed from a telephone line.
[0050]
When automatic bathing operation is turned on, hot water filling or reheating is performed on the bathtub 40 thereafter, so that such operation is completed and the hot water in the bathtub 40 is kept warm. When entering, the state of the sensor combined with the automatic operation of the bath may be checked.
[0051]
In addition, in the embodiment, the hot water in the heat exchanger 13 is kept warm by intermittently burning the burner 12 with the minimum combustion amount for 2 seconds, but the hot water in the heat exchanger 13 is kept warm. The form of combustion control is not limited to this as long as it can be maintained within the temperature range. Moreover, although the heat retention function is forcibly turned on for 5 minutes after the hot water supply operation is stopped, the on time at that time is not limited to 5 minutes. In addition, it may be possible to select whether or not to enable the heat retention operation for 5 minutes after stopping the hot water by a predetermined operation, and it is not always necessary to provide the heat retention function for 5 minutes.
[0052]
Furthermore, in the embodiment, the heat retention temperature in the heat exchanger 13 is set to be high and the hot water temperature is lowered to the set temperature by bypass mixing, and the hot water is discharged. However, there is no bypass mixing or the mixing ratio is fixed. It may be. However, in these cases, the hot water temperature cannot be arbitrarily adjusted depending on the amount of mixing, so the hot water of the heat exchanger 13 must be kept at an accurate temperature corresponding to the set temperature. Note that the water heater is not limited to the one can two water channel type as shown in the embodiment.
[0053]
【The invention's effect】
According to the water heater according to the present invention, the operation accepting unit has a heat retaining function for keeping the water in the heat exchanger within the predetermined heat retaining temperature range by burning the burner without passing water and preparing the next hot water in the hot water. Since the setting state from the sensor and the detection state of the sensor has become a predetermined combination, the time zone in which the shower is used is determined, and it is turned on and off according to the determination result. Compared to the case where only one of the detection states is based, it is possible to control on / off of the heat retaining function more finely.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a water heater according to an embodiment of the present invention.
FIG. 2 is a front view showing a remote control unit included in the water heater according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram illustrating an example of a correspondence relationship between a combination of a setting state based on an operation and detection states of various sensors and on / off control of a heat retaining function;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Hot water heater 12 ... Burner 13 ... Heat exchanger 21 ... Hot water supply pipe 27 ... Incoming thermistor 28 ... Outlet thermistor 29 ... Heat exchanger thermistor 31 ... Recirculation pipe 37 ... Water level sensor 40 ... Bathtub 50 ... Control base 51 ... Thermal insulation control unit 52 ... Normal combustion control unit 53 ... Communication unit 60 ... Remote control unit 61 ... Operation unit 62 ... Display unit 63a ... Up switch 63b ... Down switch 64a ... Priority switch 65 ... Operation switch 66 ... Automatic switch 67 ... Call switch 68 ... Agitation switch 69 ... Ume switch 71 ... Telephone line 72 ... Human sensor 73 ... Outside air temperature sensor 74 ... Light sensor

Claims (5)

In a water heater with a heat retaining function that keeps the water in the heat exchanger within the predetermined heat retaining temperature range in preparation for the next hot water by burning the burner without passing water,
Thermal insulation control means for controlling the thermal insulation operation for carrying out the thermal insulation function, an operation accepting unit for accepting various operations, and a predetermined state as a basis for determining whether or not the thermal insulation operation should be detected And a sensor to
The heat retention control means determines a time zone in which the shower is used when the set state from the operation receiving unit and the output state of the sensor have a predetermined combination, and the heat retention is determined according to the determination result. A water heater characterized by starting operation.   2. The heat insulation control unit starts the heat insulation operation when a predetermined period has elapsed after the setting state from the operation reception unit and the output state of the sensor are combined with each other. Water heater.   2. The heat insulation control unit stops the heat insulation operation when a predetermined time has elapsed after the setting state from the operation reception unit and the output state of the sensor are combined. Water heater. In a water heater with a heat retaining function that keeps the water in the heat exchanger within the predetermined heat retaining temperature range in preparation for the next hot water by burning the burner without passing water,
Thermal insulation control means for controlling the thermal insulation operation for carrying out the thermal insulation function, an operation accepting unit for accepting various operations, and a predetermined state as a basis for determining whether or not the thermal insulation operation should be detected And a sensor to
The heat retention control means determines a time zone in which the shower is used when the set state from the operation receiving unit and the output state of the sensor have a predetermined combination, and the heat retention is determined according to the determination result. A water heater characterized by stopping its operation.   5. The heat retention control unit stops the heat retention operation when a predetermined time has elapsed since the set state from the operation receiving unit and the output state of the sensor are combined. Water heater.

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