JP5035594B2 - Heat source machine and its pump freeze release method - Google Patents

Description

  The present invention relates to a heat source apparatus including a pump that circulates hot water and a method for releasing the freeze of the pump, and more particularly to an apparatus having a feature in a thawing operation for thawing accumulated water frozen in a pump.

  In a heat source device including a pump that circulates warm water for heating, water may freeze in the warm water circulation path or in the pump when the outside air temperature decreases. After the heat source device is once installed and the operation is started, the freezing prevention operation is performed when the outside air temperature decreases, so that the water does not freeze in the circulation path of the hot water and the pump. However, in the installation stage of the heat source device, about 5 to 10 cc of water that has remained in the pump at the end of the inspection operation after the manufacture of the heat source device may freeze. If the heat source device is tested in the frozen state, the pump may not operate normally and overheat, which may adversely affect the motor in the pump and the surrounding substrate.

  On the other hand, various freezing prevention operation techniques for preventing freezing of water in a water heater pipe or a pump when the outside air temperature is low have been proposed. For example, in Patent Document 1, in order to prevent freezing of a hot water supply device, when a freezing temperature is detected, a circulating pump is energized to perform a freezing prevention operation, and the power supply rate to the pump is changed according to the outside air temperature and consumed. An antifreezing device for a hot water supply device that saves electric power is disclosed.

Patent Document 2 discloses a pump control that prevents freezing of water in a pipe or a pump by energizing the pump for a short period of time every predetermined period corresponding to the capacity of the pump when the outside air temperature becomes a predetermined value or less. An apparatus is disclosed.
In Patent Document 3, when the water temperature in the canned motor pump is lowered, a current that does not rotate the rotor from the low-voltage power supply is supplied to the motor, and the low-voltage power supply is controlled according to the water temperature. A freeze prevention device for a canned motor pump that prevents freezing with generated heat is disclosed.

  In Patent Document 4, the output of a brushless motor is connected to an impeller of a pump via a one-way clutch (torque transmission only during forward rotation), and the motor is rotated in a reverse rotation direction for a predetermined time for freezing and thawing in a low temperature atmosphere. Thus, anti-freezing technology is disclosed in which the temperature of the motor is increased, and then the motor is rotated in the normal direction, and when the lock current is generated by the normal rotation, the motor is reversely rotated again.

Japanese Utility Model Publication No. 5-79345 Japanese Patent Publication No. 7-99157 Japanese Patent Laid-Open No. 11-153098 JP 2005-299617 A

Since the anti-freezing device for a water heater in Patent Document 1 is an anti-freezing device and not a device for thawing freezing, when the anti-freezing operation is performed in a state where the water in the pipe or the pump is frozen. The motor in the locked state generates a large amount of heat, which may damage the motor and its nearby substrate.
Since the device of Patent Document 2 is also a device for preventing freezing and not a device for thawing freezing, energization of a motor with a minute time for each predetermined period takes a lot of time and is suitable for thawing. It is not a thing.

The anti-freezing device of Patent Document 3 is also an anti-freezing device, not a device for thawing freezing, but only supplies a minute current that does not rotate the motor for anti-freezing. It takes a long time to defrost and is not suitable for thawing.
The device of Patent Document 4 can thaw freezing and prevent freezing, but it is necessary to equip a one-way clutch between the motor output shaft and the impeller, which complicates the structure of the pump, It is disadvantageous in production cost.

  An object of the present invention is to make it possible to efficiently thaw the accumulated water frozen in the pump through the energization of the motor in a heat source machine equipped with a hot water circulation pump, and to adversely affect the motor and the substrate. And making it possible to perform thawing according to the ambient temperature, enabling thawing without complicating the structure of the pump, and the like.

The heat source device according to claim 1 is a heat source device including a pump for circulating hot water, and mode setting means for setting a thawing operation mode for releasing freezing of the accumulated water frozen in the pump, and the mode setting means When the thawing operation mode is set, a thawing control means for performing a thawing operation for intermittently energizing the pump and thawing freezing of the accumulated water by the heat generated by the pump , the thawing control means after the thawing operation ends When the thawing operation mode is set again by the mode setting means, if the set time has not elapsed since the end of the previous thawing operation, the thawing operation is started after the set time has elapsed. .

  When the thawing operation mode is set by the mode setting means for setting the thawing operation mode for releasing freezing of the accumulated water frozen in the pump, the thawing control means intermittently energizes the pump to generate heat of the pump. Thaw operation is performed to thaw the frozen water frozen at

The heat source apparatus according to claim 2 is characterized in that, in the invention according to claim 1, the thawing operation is an operation in which a thawing cycle in which the pump is turned on for a predetermined time and then turned off is performed a plurality of times.
According to a third aspect of the present invention, there is provided the heat source apparatus according to the second aspect of the present invention, further comprising an atmospheric temperature detecting means for detecting the atmospheric temperature, and the thawing control means is detected from a plurality of predetermined times preset in association with the atmospheric temperature. The predetermined time corresponding to the ambient temperature is selected.

According to a fourth aspect of the present invention, in the invention according to the second or third aspect, the thawing control unit includes a counting unit that counts the number of executions of the thawing cycle, and ends the thawing operation after a predetermined number of thawing cycles. It is characterized by doing.
According to a fifth aspect of the present invention, there is provided the heat source apparatus according to any one of the first to third aspects, further comprising a thawing completion detecting means for detecting completion of freezing and thawing, and the completion of thawing is detected by the thawing completion detecting means. In some cases, the thawing control means ends the thawing operation.

According to a sixth aspect of the present invention, there is provided the heat source apparatus according to any one of the first to fifth aspects, further comprising display means for displaying that the thawing operation mode is set.
According to a seventh aspect of the present invention, there is provided the heat source device according to any one of the first to sixth aspects, wherein the hot water circulation path includes a hot water tank, and the thawing control means is based on a detection result by the means for detecting the water level of the hot water tank. The thawing operation is performed on condition that the water level of the hot water tank is above a certain level.

According to the invention of claim 1, when the thawing operation mode is set by the mode setting means for setting the thawing operation mode for releasing the freezing of the accumulated water frozen in the pump, the pump is intermittently And a thawing control means for performing a thawing operation for thawing freezing of the accumulated water by the heat generated by the pump, and in order to defrost by intermittent energization of the pump, Thawing can be performed reliably, the pump does not overheat, and adverse effects on the pump and the substrate can be prevented.
Further, when the thawing mode is set again by the mode setting means after completion of the thawing operation, the thawing control means defrosts after the set time has elapsed if the set time has not elapsed since the end of the previous thawing operation. Since the operation is started, it is possible to reliably prevent the pump from overheating by starting the thawing operation again before the set time has elapsed after the end of the thawing operation.

  According to the invention of claim 2, since the thawing operation is an operation in which a thawing cycle in which the pump is turned on for a predetermined time and then turned off is performed a plurality of times, the pump is surely warmed while preventing the pump from overheating. Can be thawed.

  According to the invention of claim 3, in the invention of claim 2, there is provided atmosphere temperature detection means for detecting the atmosphere temperature, wherein the thawing control means is based on a plurality of predetermined times preset in association with the atmosphere temperature. Since the predetermined time corresponding to the detected atmospheric temperature is selected, the predetermined time can be shortened as the atmospheric temperature becomes higher, the thawing operation according to the atmospheric temperature can be performed, and the pump is overheated. It can be surely prevented.

  According to the invention of claim 4, in the invention of claim 2 or 3, the thawing control means includes a counting means for counting the number of executions of the thawing cycle, and performs a thawing operation after a predetermined number of thawing cycles. Since it complete | finishes, it can prevent more reliably that a pump overheats.

  According to a fifth aspect of the present invention, the thawing completion detecting means for detecting completion of freezing and thawing is provided, and when the completion of thawing is detected by the thawing completion detecting means, the thawing control means ends the thawing operation. Therefore, it is possible to reliably prevent useless thawing operation after thawing is completed.

According to the sixth aspect of the present invention, since the display means for displaying that the thawing operation mode is set is provided, it is possible to surely know that the thawing operation mode has been entered.
According to the invention of claim 7 , the hot water circulation path is provided with a hot water tank, and the thawing control means is based on a detection result by the means for detecting the water level of the hot water tank. Since the thawing operation is performed under the conditions, it is possible to reliably prevent the air-mixed water from being supplied from the pump to the hot water circulation path.

  The heat source apparatus of the present invention is provided with mode setting means for setting a thawing operation mode for releasing freezing of frozen water in the pump for circulating hot water, and when the thawing operation mode is set by the mode setting means Further, a thawing control means is provided for performing a thawing operation in which the pump is intermittently energized and the frozen water is thawed by the heat generated by the pump.

Embodiments of the present invention will be described below with reference to the drawings.
A heat source unit 1 shown in FIG. 1 is for supplying hot water to the heating terminals 2 and 3. The heat source unit 1 includes a gas proportional valve 5 provided in a gas supply pipe 4, a heating hot water generator 6, A water supply pipe 7, an expansion tank 8 connected to the water supply pipe 7, a pump 9 incorporating a canned motor, a heating / hot water return pipe 10, a heating / cold water supply pipe 11, a heating / hot water supply pipe 12, and a bypass thermal valve 32a, control unit 15 and the like. The heat source device 1 is accommodated in a case 16.
The low temperature heating terminal 2 is connected to the heating low temperature water supply pipe 11, the high temperature heating terminal 3 is connected to the heating high temperature water supply pipe 12, and the heating hot water returning from the low temperature heating terminal 2 and the high temperature heating terminal 3 is a heating hot water return pipe. 10 is configured to return to the expansion tank 8.

  The heating / warm water generator 6 includes a combustion section 19 including a combustion pipe 17 and a gas solenoid valve 18, a combustion fan 20 that sends air to the combustion section 19, a heat exchanger 21, a spark plug 22, a turn-off safety device 23, and a burner 24. , An overheat prevention device 25, an empty safety device 26, a high temperature thermistor 27, a rotation speed sensor 28, and the like. The fuel gas is supplied from the gas inlet 4 a to the gas supply pipe 4 and is supplied to the combustion unit 19 through the gas proportional valve 5.

  Water is supplied from the water supply port 7 a to the water supply pipe 7, filtered by the water filter 30, and supplied to the expansion tank 8. A freeze prevention heater 31 is provided at the water filter 30. A primary side inlet pipe 13 extends from the expansion tank 8 to the heat exchanger 21, and the heating low temperature water pipe 11 branches from the primary side inlet pipe 13. The secondary side hot water discharge pipe 14 of the heat exchanger 21 is connected to the heating high temperature water pipe 12. A pump 9 is disposed near the expansion tank 8, and the pump 9 is interposed in the primary water inlet pipe 13. The heating / warming water return pipe 10 is connected to the heating / hot water supply pipe 12 or the secondary hot water supply pipe 14 by bypass pipes 32 and 33, and a bypass thermal valve 32 a is interposed in the bypass pipe 32. The pump 9 incorporates an encoder 45 for detecting the rotational speed.

  The expansion tank 8 is provided with a water filter 35, a replenishing water solenoid valve 36, a manual replenishing port 37, a low temperature thermistor 38, a low water level electrode 39, a high water level electrode 40, and the like. It is detected whether the water level in the expansion tank 8 is higher than a predetermined low level via the low water level electrode 39 and whether the water level in the expansion tank 8 is higher than a predetermined high level via the high water level electrode 40. Is done. An outside temperature thermistor 41 that detects the ambient temperature (outside temperature) is provided inside the lower portion of the case 16.

  The control unit 15 (which corresponds to the thawing control means) has an input / output interface and a microcomputer, and a control program for thawing operation control described later is stored in advance in the ROM of the microcomputer. Signals from sensors and switches provided in the heat source device 1 are input to the control unit 15, and drive signals are output from the control unit 15 to each control target device.

In particular, a control system necessary for the thawing operation control of the present application will be described.
As shown in FIG. 2, the control unit 15, a command signal from MizuCho squirrel switch 43 for setting the operation mode of the water filling commissioning command signal from the error read-out switch 44, the detection signal of the outside air temperature thermistor 41, the pump 9 encoder signals, detection signals of the low water level electrode 39 and the high water level electrode 40, and signals from other sensors and switches. The control unit 15 is also provided with a seven-segment display 42 (display means). The control unit 15 receives a drive signal (drive current) for driving the pump 9 and a drive signal for driving the display 42. Is output.

  Next, the thawing operation control executed by the microcomputer of the control unit will be described. In this thawing operation control, when the water staying in the pump 9 (about 5 to 10 cc) is frozen in the installation stage of the heat source device 1, the pump 9 is intermittently energized (canned in the pump). This is a control for thawing the stagnant water frozen by the heat generated by the pump 9 by energizing the motor.

For this thawing operation control, the following counters and timers are provided in the microcomputer RAM according to the thawing operation control program.
"Pump ON counter" ··· Counts the number of energizations to the pump 9 during the thawing operation.
“Pump ON Timer”-Times continuous energization to the pump 9.
“Pump OFF timer”-Times the power supply to the pump 9 is stopped.
“Continuous operation avoidance timer”... Time elapsed from the end of the thawing operation consisting of intermittent energization a plurality of times (three times in this embodiment).
FIG. 3 is a time chart showing an energization operation in which the pump 9 is energized three times intermittently in the thawing operation, and FIGS. 4 and 5 are flowcharts of the thawing operation control.

Next, a flowchart of the thawing operation control will be described with reference to FIGS.
In the figure, Si (i = 1, 2,...) Indicates each step. Moreover, the following description includes the description about the pump freezing release method.
This thawing operation control is started by turning on the power to the control unit 15, and it is first determined whether or not a thawing operation command is input (S1). In the heat source device 1, when the holding-type water filling switch 43 is ON, it is determined that the defrosting operation command has been input by pressing the error call switch 44 for 3 seconds.
When the thawing operation command is input, in S2, the thawing operation mode flag F is set to “1”, and “8” indicating that the thawing operation mode is entered is displayed on the display 42 and displayed. Is retained. Next, in S3, the pump ON counter N is set to N = 0.

  Next, in S4, it is determined whether or not the continuous operation avoidance timer is up in order to determine whether or not a set time (for example, t3 = 10 minutes at t3 in FIG. 3) has elapsed since the end of the previous thawing operation. The If this is the first thawing operation, the determination in S4 is Yes, and whether or not the low water level electrode 39 is ON in S5, that is, water has entered at least the level of the low water level electrode 39 in the expansion tank 8. Judgment is made. When this determination is No, S5 is repeated, and when the determination of S5 becomes Yes due to the progress of water filling, the process proceeds to S6.

Here, in the case of the present embodiment, as shown in FIG. 3, the thawing operation is an operation in which the thawing cycle in which the pump 9 is energized for a predetermined time and then the energization is turned off is performed a plurality of times (in this embodiment, three times). . When power is supplied to the canned motor of the pump 9 in a state where the accumulated water is frozen, the canned motor generates heat and transfers heat to the inside of the pump, and the freezing is gradually thawed.
The energization time t1 of intermittent energization in the thawing operation is 27 minutes when the outside air temperature is 5 ° C. or lower, 17 minutes when the outside air temperature is higher than 5 ° C., and the energization stop time t2 is 3 minutes. Yes. This is to promote thawing when the outside air temperature is low and to prevent the pump 9 from overheating when the outside air temperature is high.

  Next, in S6, it is determined whether or not the outside air temperature is 5 ° C. or less based on the detection signal from the outside air temperature thermistor 41. If the outside air temperature is 5 ° C. or less, 27 minutes is set in the pump ON timer in S7. Then, energization of the pump 9 is started. Next, in S8, it is determined whether or not the pump ON timer has expired (27 minutes have passed). If the determination is No, in S9, based on the encoder signal from the encoder 45 attached to the pump 9. It is determined whether or not the pump 9 is rotating. Since the determination is No at first, the process returns to S8, repeats S8 and S9, energizes for 27 minutes, and when the determination of S8 becomes Yes, the process proceeds to S13.

On the other hand, when the outside air temperature is higher than 5 ° C., the process proceeds from S6 to S10, and in S10, 17 minutes is set in the pump ON timer, and energization of the pump 9 is started. Next, in S11, it is determined whether or not the pump ON timer has timed out (17 minutes have passed). If the determination is No, in S12, based on the encoder signal from the encoder 45 attached to the pump 9. , the pump 9 is determined whether rotating, first the determination returns to step S11 because it is No, S11, S12 repeatedly, the energization to the S1 1 determined 17 minutes becomes to Yes, the process proceeds to S13 .

  In S13, energization of the pump 9 is stopped and the pump ON counter N is incremented by "1". In the next S14, it is determined whether or not the count value of the pump ON counter is less than 3, and the determination is Yes. In S15, the pump OFF timer is set to 3 minutes, and then in S16, it is determined whether or not 3 minutes have elapsed. S3 is repeated before 3 minutes have elapsed, and when the energization stop time of 3 minutes has elapsed, the process proceeds to S5. S5 and subsequent steps are repeated in the same manner as described above. If the frozen accumulated water in the pump 9 is defrosted and the pump 9 starts rotating while the intermittent energization is being executed, the determination in S9 or S12 is Yes.

  If the determination in S9 is Yes, the energization to the pump 9 is stopped in S17, the pump ON counter is cleared, and in the next S18, the flag F is reset to 0 to cancel the thawing operation mode, and the display 42 The display is switched to a display other than “8” (for example, a display of “0”). If the determination in S12 is Yes, energization of the pump 9 is stopped in S19, the pump ON counter is cleared, and in the next S20, the flag F is reset to 0 to cancel the thawing operation mode, and the display 42 The display is switched to a display other than “8” (for example, a display of “0”).

  Also, if the pump 9 is energized three times, the determination in S14 is No and the process proceeds to S21. In S21, the energization of the pump 9 is stopped and the continuous operation avoidance timer is set to 10 minutes (in FIG. 3). t3) is set, the pump ON counter is cleared, and then in S22, the flag F is reset to 0 in order to cancel the thawing operation mode, and the display 42 displays other than “8” (for example, “ ("0" display), and then returns to S1.

If the outside air temperature is very low and the pump 9 does not start rotating even after the first thawing operation (three energizations) is performed, the operator inputs the thawing operation command again. In that case, S1 to S3 are executed in the same manner as described above. In S4, it is determined whether or not the continuous operation avoidance timer has expired, that is, whether or not 10 minutes have elapsed since the end of the previous thawing operation. If not, the process waits while repeating S4, and proceeds to S5 after the continuous operation avoidance timer expires.
As described above, since the continuous operation avoidance timer and the step of S4 are provided, the thaw operation is reliably prevented from being performed again immediately after a sufficient time has not elapsed after the end of the previous thaw operation. The overheating of the pump 9 can be prevented.

  As described above, in the thawing operation, intermittent energization to the pump 9 is executed up to three times. However, if the freezing is thawed and the pump 9 starts rotating before being energized three times, the thawing operation is performed. Ends and the thawing operation mode is canceled. Even if the thawing operation command is input again after execution of the thawing operation, the thawing operation is not substantially started until 10 minutes have passed after the 10 minutes set in the continuous operation avoidance timer have elapsed. The thawing operation is substantially started.

  Since the thawing is performed by intermittent energization of the pump 9, it is possible to surely thaw the accumulated water frozen in the pump 9, preventing the pump 9 from overheating and preventing adverse effects on the pump 9 and the substrate. . The thawing operation is an operation in which the pump 9 is turned on for a predetermined time (17 minutes or 27 minutes) and then the thawing cycle in which the pump 9 is turned off for 3 minutes is performed a plurality of times. Can be warmed and thawed.

An outer air temperature thermistor 41 for detecting the ambient temperature, pre-set in association with outside air temperature has been a cage of energizing time (27 min, 17 min) from to select the energizing time corresponding to the sensed outside air temperature The energization time can be shortened as the outside air temperature increases, the thawing operation according to the outside air temperature can be performed, and the pump 9 can be reliably prevented from overheating. A pump ON counter that counts the number of executions of the thawing cycle is provided, and after the thawing cycle is performed three times, the thawing operation is terminated, so that the pump 9 can be more reliably prevented from overheating.

Based on the encoder signal from the encoder 45 of the pump 9, it is configured to detect completion of freezing and thawing, and when the completion of thawing is detected, the thawing operation is terminated. Can be surely prevented.
When the thawing operation mode is set again after completion of the thawing operation, if the set time (10 minutes) has not elapsed since the end of the previous thawing operation, the thawing operation starts after the set time has elapsed. It is possible to reliably prevent the pump 9 and the substrate from being overheated by starting the thawing operation again before the set time elapses after the end of.

  Since the display 42 for displaying that the thawing operation mode is set is provided, it is possible to surely know that the thawing operation mode has been entered. An expansion tank 8 (which corresponds to a hot water tank) is provided in the circulation path of the hot water, and the water level of the expansion tank 8 is above a certain level based on the detection result by the low water level electrode 39 that detects the water level of the expansion tank 8. Since the thawing operation is started on the condition of the above, it is possible to reliably prevent supply of water mixed with air from the pump 9 to the circulation path of the hot water.

Next, an example in which the above embodiment is partially changed will be described.
(1) Although the said Example demonstrated the heat source machine which supplies warm water to the heating terminals 2 and 3 as an example, this invention is applicable similarly to heat source machines, such as a water heater.
(2) In the thawing operation, the energization time t1 (27 minutes or 17 minutes), the energization stop time t2 (3 minutes), the continuous operation avoidance time t3 (10 minutes) from the end of the thawing operation to the next thawing operation start, etc. It is only an example, and can be changed as appropriate according to the capacity of the pump 9 or the area where the heat source unit 1 is installed. For t1 = 27 minutes or 17 minutes, t2 = 3 minutes, t3 = 10 minutes It is only an example and is not limited to these times.

(3) The number of times of energization in the thawing operation can be changed as appropriate according to the capacity of the pump 9 and the installation area of the heat source device, etc. as described above. The number of times may be less, or the number of times may be more than three.
(4) Regarding the outside air temperature, the outside air temperature is not divided into 5 ° C or less and over 5 ° C, but the outside air temperature is divided into three or more stages, and three or more energization times that become smaller as the outside air temperature increases are reduced. It may be adopted.

(5) Instead of setting the thawing operation mode with the water filling switch 43 and the error call switch 44, a dedicated switch for setting the thawing operation mode may be provided.
(6) As a means for detecting the completion of thawing, in the above embodiment, the completion of the thawing is determined by detecting the rotation of the pump 9 based on the encoder signal of the encoder 45 provided in the pump 9, but in addition to this, for example, A water flow switch may be provided in the circulation path (such as the primary side inlet pipe 13), and it may be determined that the thawing is completed when the water flow is detected by the water flow switch.
(7) In addition, those skilled in the art can implement the present invention in various forms with various modifications without departing from the spirit of the present invention, and the present invention includes such various modifications. To do.

It is a block diagram of the heat source machine which concerns on the Example of this invention. It is a block diagram of a control system related to thawing operation control. It is a time chart of the electricity supply operation | movement which supplies with electricity intermittently to a pump in the thawing | decompression operation. It is a part of flowchart of thawing | decompression operation control. It is the remainder of the flowchart of thawing | decompression operation control.

1 Heat source machine 9 Pump 15 Control unit (thawing control means)
39 Low water level electrode 40 High water level electrode 41 Outside temperature thermistor (atmosphere temperature detection means)
42 Display (display means)
43 Water filling switch (part of thawing operation mode setting means)
44 Error call switch (part of decompression operation mode setting means)
45 Encoder (decompression completion detection means)

Claims (7)

In a heat source machine equipped with a pump that circulates hot water,
A mode setting means for setting a thawing operation mode for canceling the freezing of the frozen accumulated water in the pump,
When thawing operation mode is set by said mode setting means, and a decompression control means for performing decompression operation the pump intermittently is energized by thawing the frozen accumulated water in the heating pump,
When the thawing operation mode is set again by the mode setting means after completion of the thawing operation, if the set time has not elapsed since the end of the previous thawing operation, the thawing control means A heat source machine characterized by starting .   The heat source apparatus according to claim 1, wherein the thawing operation is an operation in which a thawing cycle in which the pump is turned on for a predetermined time and then turned off is performed a plurality of times.   An ambient temperature detecting means for detecting an ambient temperature, wherein the thawing control means selects the predetermined time corresponding to the detected ambient temperature from a plurality of preset predetermined times associated with the ambient temperature. The heat source machine according to claim 2, wherein   4. The heat source apparatus according to claim 2, wherein the thawing control unit includes a counting unit that counts the number of executions of the thawing cycle, and ends the thawing operation after a predetermined number of thawing cycles. 5.   2. A thawing completion detection means for detecting completion of freezing and thawing, and when the completion of thawing is detected by the thawing completion detection means, the thawing control means ends the thawing operation. Heat source machine in any one of -3. The heat source apparatus according to any one of claims 1 to 5 , further comprising display means for displaying that the thawing operation mode is set . A hot water circulation path is provided with a hot water tank, and the thawing control means performs a thawing operation on the condition that the water level of the hot water tank is above a certain level based on a detection result by a means for detecting the water level of the hot water tank. The heat source machine according to any one of claims 1 to 6 .

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