JP5206200B2 - Control device for hot water storage water heater - Google Patents

Description

  The present invention relates to a control device for a hot water storage type hot water heater.

  An exhaust chamber connected to the exhaust cylinder is provided adjacent to the upper surface plate of the cylindrical can body, and a combustion chamber is disposed inside the lower portion of the can body, and the lower end of the cylindrical combustion chamber side wall of the combustion chamber is the can Connected to the body. The combustion chamber top plate of the combustion chamber faces the top plate of the can body, and a plurality of flue pipes are attached between the top plate and the combustion chamber top plate to communicate the combustion chamber and the exhaust chamber. A hot water storage chamber is formed between the top plate of the can body and the combustion chamber top plate and the gap between the can body and the combustion chamber.

  The hot water storage chamber constitutes a heat exchange part with the cylindrical combustion chamber side wall, the flue pipe side wall and the top plate of the can body as the heat transfer area, and the tip of the burner attached to the outside of the side of the can body is the combustion chamber When the burner is burned, the combustion flame and combustion gas are sent to the combustion chamber, and the high-temperature combustion gas is discharged from the stack through the exhaust chamber through the flue pipe, and is stored in the hot water storage chamber at this time. Water is heated.

  A water supply pipe is opened on the lower side wall of the can body, a hot water discharge pipe is opened on the upper side wall of the can body, and a hot water temperature sensor is attached to the side wall of the can body between the water supply pipe and the hot water discharge pipe. When hot water flows toward the pipe, cold water enters the hot water storage chamber from the water supply pipe, is heated by the heat of the burner, and is heated to a hot water discharge pipe. At this time, the hot water temperature is monitored by the hot water temperature sensor, and the burner obtains the desired hot water temperature by repeating the operation and the stop by the output of the hot water temperature sensor.

  That is, a hot water temperature sensor is provided on the side wall of the can body, and a temperature setting means is provided in the operation section of the water heater. When the hot water temperature falls below the temperature setting means, the hot water temperature sensor detects and the burner control means burns. By issuing a command, the burner repeats burning and extinguishing, and the hot water stored in the hot water storage chamber of the can is kept at a constant hot water temperature.

Generally, a hot water temperature sensor is installed on the side wall of the can between the water supply pipe and the hot water discharge pipe, and a burner that repeats extinction and ignition is ignited by detecting a hot water temperature change early and issuing a combustion command to the burner control means. Even if a certain period of time is required during the transition from to stable combustion, the cold water sent from the water supply pipe is heated quickly.
JP 2003-74975 A

  When the hot water storage type hot water heater is not used for a long time, the hot water temperature in the hot water storage room decreases due to heat dissipation, and if the hot water temperature falls below the set temperature, the burner control means issues a combustion command, and the burner burns and is set This is to maintain the hot water temperature. For this reason, if the hot water heater is kept operating for a long period of non-use, the burner is repeatedly burned and wastes fuel, and the noise and vibration generated during burner combustion. Therefore, burning the burner several times with the hot water heater operating at night may cause noise complaints.

  On the other hand, if the hot water heater is turned off when hot water is not used for a long time, the burner will not burn and wasteful fuel consumption and noise will not occur. Since the hot water temperature of the hot water will drop, it will take a long time for the hot water in the hot water storage room to boil up to the set temperature after starting the water heater, and the hot water cannot be used immediately. there were.

  The present invention solves the above-described problem. An exhaust chamber 2 is provided adjacent to the upper surface plate 1a of the cylindrical can body 1, and a combustion chamber top plate 3a is disposed on the inner side of the lower portion of the can body 1 as an upper surface plate. A combustion chamber 3 facing the la and having the lower end of the cylindrical combustion chamber side wall 3b connected to the can body 1 is disposed, and between the top plate 1a and the combustion chamber top plate 3a of the can body 1 and the can body 1 and a combustion chamber side wall 3b constitute a hot water storage chamber 4, and a combustion chamber 3 and an exhaust gas to which a burner 6 is connected by attaching a plurality of flue pipes 5 between the top plate 1a and the combustion chamber top plate 3a. The water supply pipe 7 is opened on the lower side wall of the can body 1, the hot water discharge pipe 8 is opened on the upper side wall of the can body 1, and the side wall of the can body 1 between the water supply pipe 7 and the hot water discharge pipe 8 is communicated with the chamber 2. In a water heater equipped with a hot water temperature sensor 9, the combustion of the burner 6 is opened based on the temperature setting means 10 for setting the hot water temperature and the signal from the hot water temperature sensor 9. A burner control means 11 for instructing a stop, a timer means 12 for measuring a predetermined time t, and a set temperature changing means 13 for changing the set temperature ST of the temperature setting means 10, and a combustion stop signal of the burner control means 11. The timer means 12 starts counting, and the set temperature changing means 13 changes from the set temperature ST of the temperature setting means 10 to the set temperature TL lower than the set temperature TL by the signal counted by the timer means 12, and the burner control means 11 changes. The start of combustion of the burner 6 is instructed based on the later set temperature TL.

  Further, there is provided reset means 14 for returning the set temperature TL of the set temperature changing means 13 to the set temperature ST of the temperature setting means 10, and the reset means 14 detects the set temperature TL when the hot water temperature sensor 12 detects the set temperature TL. The burner control means 11 operates when a combustion start signal is output, and the burner control means 11 instructs the stop of combustion of the burner 6 based on the set temperature ST after the return, so that it is not used for a long time. Since the difference between the combustion start temperature and the combustion stop temperature of the burner 6 increases, the time during which the burner 6 is stopped is lengthened, and the number of combustions of the burner 6 can be reduced.

  Further, there is provided canceling means 15 that operates when the set temperature ST of the temperature setting means 10 is equal to or lower than a predetermined temperature. When the canceling means 15 is operated, the timer means 12 counts with a combustion stop signal from the burner control means 11. By maintaining the set temperature ST of the temperature setting means 10 without performing the above, when the set temperature ST is low, the time for the hot water temperature to drop to the set temperature ST becomes long, and even when the burner 6 is not used for a long time, Since the number of times of combustion is small, priority is given to usability while maintaining the set temperature ST.

  The timer means 12 has two timekeeping functions for counting the stop time of the burner 6, the set temperature changing means 13 has two set temperatures TL1 and TL2, and the set temperature changing means 13 has the timer The means 12 changes the set temperature ST from the set temperature ST to the first set temperature TL1 which is lower than the set temperature by the output obtained by counting up the short predetermined time t1, and outputs the preset value from the first set temperature TL1 by outputting the long preset time t2. By changing to the low second set temperature TL2, the burner 6 starts to burn at the first set temperature TL1 when the hot water is used before the timer means 12 counts the long predetermined time t2, so the interval is increased. When hot water is used, it is possible to prevent the temperature of the hot water from decreasing and to prevent uneven temperature of the hot water. It is possible to reduce the number of combustions of Na 6.

In the present invention, the timer means 12 starts counting by the combustion stop signal of the burner control means 11, and the set temperature changing means 13 changes the set temperature ST to the set temperature TL lower by a predetermined temperature by the signal counted up by the timer means 12. When the hot water temperature in the hot water storage chamber 4 decreases due to heat dissipation after a long period of non-use, the time until the hot water temperature decreases to the set temperature TL becomes longer, so the time during which the burner 6 is stopped As a result, the number of combustions of the burner 6 can be reduced and the fuel can be saved, and noise generated by the combustion of the burner 6 can be suppressed.
Further, since the hot water stored in the hot water storage chamber 4 maintains the set temperature TL and does not significantly lower the hot water temperature, the hot water in the hot water storage chamber 4 can be quickly set to the set temperature of the temperature setting means 10 when the burner 6 starts combustion. Since it rose to ST, hot water could be used immediately even when hot water was used after prolonged non-use.

  Further, when the hot water temperature sensor 9 detects a temperature lower than the set temperature TL and the burner control means 11 outputs a combustion start signal when it has not been used for a long time, the temperature setting means 10 is returned to the set temperature ST. The hot water in the hot water storage chamber 4 is boiled up to the set temperature ST. Then, when the hot water temperature sensor 9 detects the set temperature ST and the burner control means 11 issues a combustion stop command and the timer means 12 counts up again when the unused state continues again, the set temperature changing means 13 sets the set temperature. Since it is changed to TL, the difference between the combustion stop temperature and the combustion start temperature of the burner 6 is increased, and the time from the stop of the burner 6 to the start of combustion of the burner 6 is increased. The number of times can be certainly reduced.

  Further, when the set temperature ST of the temperature setting means 10 is low, the amount of heat release is also reduced. Therefore, even if the set temperature ST is not used for a long time, the burner 6 is burned fewer times. For this reason, when the set temperature ST of the temperature setting means 10 is lower than the predetermined temperature, the canceling means 15 is operated, the timer means 12 is not operated by the combustion stop signal of the burner control means 11, and the set temperature ST of the temperature setting means 10 is set. Therefore, when the use of hot water is started from a non-use state for a long time, the hot water at the set temperature ST can be used immediately, and the usability can be improved.

Further, the timer means 12 is provided with two time measuring functions, the set temperature changing means 13 is changed to the first set temperature TL1 when the short predetermined time t1 is up, and the long predetermined time t2 is up. Therefore, the time until the change to the second set temperature TL2 after the combustion of the burner 6 is stopped can be increased, and the timer means 12 has a long predetermined time. When hot water is used before counting t2, the burner control means 11 outputs a combustion start signal when the hot water temperature sensor 9 detects the first set temperature TL1, so that the hot water temperature of the hot water storage chamber 4 is The temperature can be raised to the set temperature ST of the temperature setting means 10 in a short time while suppressing the decrease, and stable hot water can be obtained even when there is an interval for using hot water, improving usability It came.
On the other hand, when the long predetermined time t2 is up without using hot water, the temperature is changed to the second set temperature TL2. Therefore, when the non-use continues for a long time, the burner 6 is kept until the temperature drops to the second set temperature TL2. Since combustion does not occur, the number of times the burner 6 burns can be reliably reduced, and wasteful fuel consumption and noise generation can be prevented.

  The present invention will be described with reference to the embodiments shown in the drawings. Reference numeral 1 denotes a cylindrical can body, 1a denotes a top plate of the can body 1, 3 denotes a combustion chamber provided inside the lower portion of the can body 1, and 3a faces the top plate 1a. The combustion chamber top plate 3b is a combustion chamber side wall provided inside the lower portion of the can body 1, 6 is a burner attached to the outside of the side portion of the can body 1, and the lower end of the combustion chamber 3 is connected to the can body 1. Thus, the flame of the burner 6 is blown into the combustion chamber 3.

  4 is a hot water storage chamber constituted by a gap between the top plate 1a of the can body 1 and the combustion chamber top plate 3a and a gap between the can body 1 and the combustion chamber side wall 3b, and 5 is a top plate 1a and the combustion chamber top plate 3a. A plurality of flue pipes attached between and 2 is an exhaust chamber provided adjacent to the upper portion of the upper surface plate 1a, 2a is an exhaust pipe connected to the exhaust chamber 2, and the combustion sent to the combustion chamber 3 The gas is sent to the exhaust chamber 2 through the inside of the flue pipe 5 and exhausted from the exhaust cylinder 2a to the outside of the room, and the water in the hot water storage chamber 4 flows from the wall surface of the combustion chamber 3, the flue pipe 5 and the top plate 1a. Heat exchanges with heat, resulting in high temperature.

  7 is a water supply pipe opened in the lower side wall of the can body 1, 8 is a tapping pipe opened in the upper side wall of the can body 1, and 9 is a can on the side of the flue pipe 5 between the water supply pipe 7 and the tapping pipe 8. A hot water temperature sensor provided on the side wall of the body 1.

  In FIG. 1, 10 is a temperature setting means for setting the hot water discharge temperature of the water heater, 16 is an operation switch for starting / stopping the operation of the water heater, and 11 is a burner control for instructing the burner 6 to start and stop combustion. The combustion start temperature and the combustion stop temperature of the burner 6 are determined based on the set temperature ST set by the temperature setting means 10. The temperature of the hot water in the hot water storage chamber 4 is monitored by the hot water temperature sensor 9, and when the combustion start temperature set by the temperature setting means 10 is detected, the burner control means 11 issues a combustion command and the burner 6 starts combustion. When the hot water stored in the hot water storage chamber 4 is boiled to a specified temperature and the hot water temperature sensor 9 detects the combustion stop temperature set by the temperature setting means 10, the burner control means 11 issues a combustion stop command and the burner 6 Stop burning.

  When the user opens a faucet (not shown) such as a kitchen or a washroom, hot water heated in the hot water storage chamber 4 is discharged from the hot water discharge pipe 8, and cold water sent from the hot water supply pipe 7 is supplied to the hot water storage chamber 4 instead. When the temperature sensor 9 detects a decrease in hot water temperature, the burner control means 11 again issues a combustion command, the burner 6 burns, and the hot water temperature set by the temperature setting means 10 can be maintained.

  As described above, when the user opens the faucet in the kitchen or the bathroom, the hot water having the set temperature ST is supplied from the tap pipe 8 first, so that the rising temperature characteristic is good, and the heat exchanging section is in the combustion chamber. Since the side wall 3b, the flue pipe 5 side wall, and the top plate 1a of the can body 1 are configured, the heat transfer area is large, and the hot water in the hot water storage chamber 4 can rise quickly, so that stable hot water with less extreme temperature unevenness. Warm hot water is obtained.

  Further, when hot water is not used, the temperature of the hot water stored in the hot water storage chamber 4 is reduced by heat dissipation, so that the burner control is performed when the hot water temperature in the hot water storage chamber 4 reaches the combustion start temperature set by the temperature setting means 10. The means 11 issues a combustion command and the burner 6 burns, and the burner 6 keeps the hot water temperature set by the temperature setting means 10 by repeating the combustion and the stop, but is not used for a long time. Sometimes, if the burner 6 burns more times, the fuel is wasted. Further, since the loud noise and vibration are generated when the burner 6 burns, it is likely to cause noise complaints when the hot water heater is operated at night.

  In order to prevent wasteful fuel consumption and noise problems, it is necessary to stop the water heater when hot water is not used for a long time. However, if the operation is stopped for a long time, the hot water temperature in the hot water storage chamber 4 is lowered. Therefore, when the operation is started, it takes time for the hot water in the hot water storage chamber 4 to boil up to the set temperature ST, and it is necessary to wait for a long time until the hot water can be used.

12 is a timer means that starts counting upon receiving a combustion stop signal from the burner control means 11 and stops counting upon receiving a combustion start signal; 13 is a set temperature changing means that changes the set temperature ST of the temperature setting means 10; When the hot water temperature sensor 9 detects the combustion stop temperature set by the temperature setting means 10 and the burner control means 11 issues a combustion stop command, the burner 6 stops combustion and instructs the timer means 12 to start counting. . When the hot water temperature sensor 9 detects the combustion start temperature set by the temperature setting means 10 and the burner control means 11 issues a combustion command while the timer means 12 is counting, combustion of the burner 6 starts and the timer The means 12 is instructed to stop counting.
On the other hand, when the timer unit 12 that has started counting counts the predetermined time t, an output signal is sent to the set temperature changing unit 13, and the set temperature changing unit 13 receives this signal and the set temperature ST set by the temperature setting unit 10. To set temperature TL lower by a predetermined temperature.

Normally, the burner 6 continues to burn even after the user stops the hot water. When the hot water temperature in the hot water storage chamber 4 rises and the hot water temperature sensor 9 detects the combustion stop temperature set by the temperature setting means 10, the burner control is performed. The means 11 outputs a combustion stop signal, and upon receiving this signal, the timer means 12 starts counting.
When the user uses hot water again while the timer means 12 is counting, cold water is supplied from the water supply pipe 7 to the hot water storage chamber 4 to lower the hot water temperature, and the hot water temperature sensor keeps the temperature set by the temperature setting means 10 or lower. When 9 is detected, the burner control means 11 outputs a combustion signal, so that the timer means 12 stops counting, and is based on the set temperature ST of the temperature setting means 10 while hot water is discharged or stopped. The burner 6 is burned and stopped.
On the other hand, when the timer means 12 counts the predetermined time t after the user stops hot water and the timer means 12 counts the predetermined time t, the set temperature changing means 13 sets the set temperature ST set by the temperature setting means 10 to the set temperature TL. Change to And if the state of non-use continues as it is for a long time, the temperature of the hot water stored in the hot water storage chamber 4 decreases due to heat dissipation, but if the temperature of the hot water decreases, the amount of heat dissipation decreases and the decrease in hot water temperature slows down. The time when the hot water temperature in the hot water storage chamber 4 is lowered to the set temperature TL is much longer than the time when the hot water temperature is lowered to the set temperature ST, and the state where the burner 6 is stopped can be maintained longer. For this reason, it is possible to reduce the number of times the burner 6 burns when the hot water heater is operated for a long period of time, thereby reducing wasteful consumption of fuel and suppressing the generation of noise due to the burner 6 combustion. I was able to.

  When the hot water is not used for a long time, the hot water temperature in the hot water storage chamber 4 is maintained at the set temperature TL. When hot water is used after the hot water has not been used for a long time, the hot water is initially lower than the set temperature ST. Is discharged, but when the cold water sent from the water supply pipe 7 is supplied to the hot water storage chamber 4 and the hot water temperature sensor 9 detects the set temperature TL, the burner control means 11 outputs a combustion signal, so the burner 6 starts burning. Then, the hot water in the hot water storage chamber 4 rises to the set temperature ST of the temperature setting means 10 in a short time, so that the hot water can be used immediately even after it has not been used for a long time, and usability can be improved.

Reference numeral 14 denotes a resetting unit that operates in response to a combustion start signal from the burner control unit 11. The hot water temperature sensor 9 is set by the set temperature changing unit 13 when the hot water temperature sensor 9 is not used for a long time. When the following is detected and the burner control means 11 issues a combustion command, the burner 6 starts combustion and the reset means 14 returns from the set temperature TL of the set temperature changing means 13 to the set temperature ST of the temperature setting means 10.
When the burner 6 starts combustion, the hot water temperature in the hot water storage chamber 4 rises. When the hot water temperature sensor 9 detects the combustion stop temperature set by the temperature setting means 10, the burner control means 11 outputs a combustion stop signal, and the burner 6 When the timer unit 12 starts counting and the timer unit 12 finishes counting as it is, the set temperature changing unit 13 changes from the set temperature ST to the set temperature TL. The temperature difference between the combustion stop temperature 6 and the combustion start temperature 6 increases.
When the hot water temperature in the hot water storage chamber 4 decreases due to heat dissipation, the time until the hot water temperature sensor 9 detects the set temperature TL again becomes longer, and the time during which the burner 6 is stopped becomes longer. When this state continues, the number of burns of the burner 6 can be reliably reduced, and wasteful consumption of fuel can be suppressed and generation of noise can be suppressed.

In another embodiment of the present invention, reference numeral 15 denotes canceling means that operates when the set temperature ST of the temperature setting means 10 is set lower than a predetermined temperature. When the canceling means 15 is operating, a burner is provided. The timer means 12 does not start counting even when the control means 11 issues a combustion stop command, and is configured to hold the set temperature ST of the temperature setting means 10 even when it is not used for a long time.
When the set temperature ST is lowered to the vicinity of the set temperature TL of the set temperature changing means 13, the heat dissipation from the hot water is small and the burner 6 is burned few times. There is no problem, and when using hot water after a long period of non-use, the hot water of the set temperature ST can be used immediately, so that the usability can be improved.

Further, in another embodiment of the present invention, the timer means 12 is provided with two time measuring functions of a short predetermined time t1 and a long predetermined time t2, and the set temperature changing means 13 is a set temperature ST of the temperature setting means 10. A first set temperature TL1 lower by a predetermined temperature and a second set temperature TL2 lower by a predetermined temperature than the first predetermined temperature TL1 are provided.
When the timer means 12 starts counting by the combustion stop command of the burner control means 11 and finishes counting for a short predetermined time t1, an output signal is sent to the burner control means 11, and the burner control means 11 receives this signal and sets the temperature. The temperature is changed to the first set temperature TL1 lower than the set temperature ST of the means 10 by a predetermined temperature.
Further, when the timer means 12 finishes counting the long predetermined time t2, the output signal is sent to the burner control means 11, and the burner control means 11 receives the signal and the second set temperature lower than the first set temperature TL1 by a predetermined temperature. Change to TL2.

By providing the two set temperatures TL1 and TL2 in this way, the predetermined time t2 for changing to the second set temperature TL2 can be set longer, and the hot water is added before the timer means 12 counts the long predetermined time t2. When used, when the hot water temperature sensor 9 detects the first set temperature TL1, the burner control means 11 issues a combustion command, so that the burner 6 burns in a state where the difference from the set temperature ST of the temperature setting means 10 is small. The hot water temperature in the hot water storage chamber 4 can be raised to the set temperature ST in a short time.
For this reason, when hot water is used at a slight interval, the burner 6 starts to burn early, so that a decrease in hot water temperature can be suppressed and a stable hot water temperature can be obtained, improving usability. It was. Further, when the non-use continues for a long time, the burner 6 does not start combustion until the hot water temperature sensor 9 detects the second set temperature TL, so that the number of combustions of the burner 6 can be surely reduced and the fuel can be reduced. In addition to reducing wasteful consumption, it was possible to reduce noise generation.

It is a block diagram of a water heater showing an embodiment of the present invention. It is sectional drawing of the water heater which shows the Example of this invention. It is a graph which shows the relationship between preset temperature and hot water temperature which show the Example of this invention. It is a graph which shows the relationship between preset temperature and hot water temperature which shows the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Can body 1a Top plate 2 Exhaust chamber 3 Combustion chamber 3a Combustion chamber top plate 3b Combustion chamber side wall 4 Hot water storage chamber 5 Flue pipe 6 Burner 7 Hot water supply pipe 8 Hot water discharge pipe 9 Hot water temperature sensor 10 Temperature setting means 11 Burner control means 12 Timer Means 13 Set temperature changing means 14 Reset means 15 Canceling means t Predetermined time t1 First predetermined time t2 Second predetermined time TL Set temperature TL1 First set temperature TL2 Second set temperature

Claims (4)

An exhaust chamber (2) is provided adjacent to the upper surface plate (1a) of the cylindrical can body (1), and a combustion chamber top plate (3a) is disposed on the inner side of the lower portion of the can body (1). ) And a combustion chamber (3) in which the lower end of the cylindrical combustion chamber side wall (3b) is connected to the can body (1),
A hot water storage chamber (4) is formed by the gap between the top plate (1a) of the can body (1) and the combustion chamber top plate (3a) and between the can body (1) and the combustion chamber side wall (3b). The combustion chamber (3) and the exhaust chamber (2) in which a plurality of flue pipes (5) are attached between the top plate (1a) and the combustion chamber top plate (3a) and the burner (6) is connected. The water supply pipe (7) is opened on the lower side wall of the can body (1) and the hot water discharge pipe (8) is opened on the upper side wall of the can body (1), and the water supply pipe (7) and the hot water discharge pipe (8) are connected. In a hot water heater in which a hot water temperature sensor (9) is attached to the side wall of the can body (1),
A burner control means (11) for instructing start and stop of combustion of the burner (6) based on a signal from a temperature setting means (10) for setting the hot water temperature and a hot water temperature sensor (9);
Timer means (12) for measuring a predetermined time (t);
A set temperature changing means (13) for changing the set temperature (ST) of the temperature setting means (10),
The timer means (12) starts counting by the combustion stop signal of the burner control means (11), and the set temperature changing means (13) is set by the set temperature (10) of the temperature setting means (10) by the signal counted by the timer means (12). ST) is changed to a preset temperature (TL) lower than the predetermined temperature,
The controller for a hot water storage type hot water heater, wherein the burner control means (11) instructs the start of combustion of the burner (6) based on the set temperature (TL) after the change. A reset means (14) for returning the set temperature (TL) of the set temperature changing means (13) to the set temperature (ST) of the temperature setting means (10);
The reset means (14) operates when the hot water temperature sensor (12) detects the set temperature (TL) and the burner control means (11) outputs a combustion start signal,
The control apparatus for a hot water storage type hot water heater according to claim 1, wherein the burner control means (11) instructs the combustion of the burner (6) to stop based on the set temperature (ST) after the return.   A canceling means (15) that operates when the set temperature (ST) of the temperature setting means (10) is below a predetermined temperature is provided, and combustion of the burner control means (11) is stopped when the canceling means (15) is operated. The control of the hot water storage type hot water heater according to claim 1 or 2, wherein the timer means (12) does not count by a signal and maintains the set temperature (ST) of the temperature setting means (10). apparatus. The timer means (12) has two time measuring functions for counting the stop time of the burner (6).
The set temperature changing means (13) includes two set temperatures (TL1) and (TL2),
The set temperature changing means (13) changes the set temperature (ST) from the set temperature (ST) to a first set temperature (TL1) lower than the set temperature by an output obtained by the timer means (12) counting up a short predetermined time (t1),
4. The method according to claim 1, wherein the first preset temperature (TL1) is changed from the first preset temperature (TL1) to the second preset temperature (TL2) which is lower by a predetermined temperature with an output obtained by counting up a long predetermined time (t2). A control device for a hot water storage type hot water heater described in the above.

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