Method for reducing transient defrost noise on an outdoor split system heat pump
A method for reducing perceived defrost noise in a heat pump is provided. The method may include energizing a fan configured to urge a heat transfer medium across a heat exchanger, and initiating a defrost cycle to warm the heat exchanger. Initiating the defrost cycle may include de-energizing a compressor fluidly coupled to the heat exchanger, and delaying for a first delay period with the fan energized and the compressor de-energized. Initiating the defrost cycle may also include energizing a reversing valve after the first delay period, to reverse a flow of a refrigerant flow between the compressor and the heat exchanger, and delaying for a second delay period with the fan energized, the compressor de-energized, and the reversing valve energized. Initiating the defrost cycle may also include de-energizing the fan. The method may also include defrosting the heat pump during the defrost cycle, and terminating the defrost cycle.
1. A method for reducing defrost noise in a heat pump, comprising: energizing a fan configured to urge a heat transfer medium across a heat exchanger; initiating a defrost cycle to warm the heat exchanger, comprising:
de-energizing a compressor fluidly coupled to the heat exchanger;
delaying for a first delay period with the fan energized and the compressor de-energized;
energizing a reversing valve after the first delay period, to reverse a flow of a refrigerant flow between the compressor and the heat exchanger, such that the refrigerant warms the heat exchanger;
delaying for a second delay period with the fan energized, the compressor de-energized, and the reversing valve energized;
energizing the compressor after the second delay period and then de-energizing the fan;
defrosting the heat pump during the defrost cycle; and
terminating the defrost cycle.
2. The method of claim 1 , wherein initiating the defrost cycle further comprises energizing an auxiliary heater configured to warm a heat transfer medium urged across another heat exchanger in fluid communication with the compressor, before completing delaying for the first delay period.
3. The method of claim 1 , further comprising evaporating the refrigerant with the heat exchanger prior to initiating the defrost cycle.
4. The method of claim 1 , wherein the second delay period is between about 1 second and about 60 seconds.
5. The method of claim 1 , wherein the second delay period is between about 10 seconds and about 15 seconds.
6. The method of claim 1 , further comprising sensing defrost conditions, the defrost conditions including at least one of expiration of a defrost interval timer and a temperature of the heat exchanger falling below a minimum value.
7. The method of claim 1 , wherein defrosting the heat exchanger comprises energizing the compressor after delaying for the second delay period so as to warm the heat exchanger.
8. The method of claim 1 , wherein terminating the defrost cycle comprises:
energizing the fan;
de-energizing the compressor;
delaying for a third delay period with the fan energized and the compressor de-energized;
de-energizing the reversing valve after the third delay period;
delaying for a fourth delay period with the reversing valve de-energized and the fan energized; and
energizing the compressor after the fourth delay period.
9. The method of claim 8 , wherein terminating the defrost cycle further comprises de-energizing an auxiliary heater before and/or during the third delay period.
10. The method of claim 8 , wherein the third delay period is between about 5 seconds and about 100 seconds.
11. The method of claim 8 , wherein the third delay period is about 30 seconds.
12. The method of claim 1 , further comprising sensing a defrost cycle termination condition to determine when to terminate the defrost cycle, the defrost cycle termination condition comprising a temperature of the heat exchanger exceeding a target temperature, an expiration of a defrost cycle timer, or both.
13. A method for reducing defrost noise in a heat pump, comprising: energizing a fan configured to urge a heat transfer medium across a heat exchanger; initiating a defrost cycle to warm the heat exchanger, comprising:
de-energizing a compressor fluidly coupled to the heat exchanger;
delaying for a first delay period with the fan energized and the compressor de-energized;
energizing a reversing valve after the first delay period, to reverse a flow of a refrigerant flow between the compressor and the heat exchanger, such that the refrigerant warms the heat exchanger;
delaying for a second delay period with the fan energized, the compressor de-energized, and the reversing valve energized;
de-energizing the fan;
defrosting the heat pump during the defrost cycle; and
terminating the defrost cycle wherein the first delay period is between about 5 seconds and about 100 seconds.
14. The method of claim 13 , wherein the first delay period is about-60 seconds.
15. A method for reducing defrost noise in a heat pump, comprising: energizing a fan configured to urge a heat transfer medium across a heat exchanger; initiating a defrost cycle to warm the heat exchanger, comprising:
de-energizing a compressor fluidly coupled to the heat exchanger;
delaying for a first delay period with the fan energized and the compressor de-energized;
energizing a reversing valve after the first delay period to reverse a flow of a refrigerant flow between the compressor and the heat exchanger, such that the refrigerant warms the heat exchanger;
delaying for a second delay period with the fan energized, the compressor de-energized, and the reversing valve energized;
energizing the compressor after the second delay period;
de-energizing the fan;
defrosting the heat pump during the defrost cycle; and
terminating the defrost cycle;
wherein terminating the defrost cycle comprises:
energizing the fan;
de-energizing the compressor;
delaying for a third delay period with the fan energized and the compressor de-energized;
de-energizing the reversing valve after the third delay period;
delaying for a fourth delay period with the reversing valve de-energized and the fan energized; and
energizing the compressor after the fourth delay period;
wherein the fourth delay period is between about 5 seconds and about 100 seconds.
16. The method of claim 15 , wherein the fourth delay period is about 10 seconds.
17. The method of claim 15 , wherein the fourth delay period is about 30 seconds.
18. A method for reducing defrost noise in a heat pump, comprising: energizing a fan configured to urge a heat transfer medium across a heat exchanger; initiating a defrost cycle to warm the heat exchanger, comprising:
de-energizing a compressor fluidly coupled to the heat exchanger;
delaying for a first delay period with the fan energized and the compressor de-energized;
energizing an auxiliary heater configured to warm a heat transfer medium urged across another heat exchanger in fluid communication with the compressor, before completing delaying for the first delay period;
energizing a reversing valve after the first delay period, to reverse a flow of a refrigerant flow between the compressor and the heat exchanger, such that the refrigerant warms the heat exchanger;
delaying for a second delay period with the fan energized, the compressor de-energized, and the reversing valve energized;
energizing the compressor after the second delay period and then de-energizing the fan;
defrosting the heat pump during the defrost cycle; and
terminating the defrost cycle, comprising:
energizing the fan;
de-energizing the compressor;
delaying for a third delay period with the fan energized and the compressor de- energized;
de-energizing the reversing valve after the third delay period;
de-energizing the auxiliary heater before and/or during the third delay period;
delaying for a fourth delay period with the reversing valve de-energized and the fan energized; and
energizing the compressor after the fourth delay period.
19. A method for reducing defrost noise in a heat pump, comprising: energizing a fan configured to urge a heat transfer medium across a heat exchanger; initiating a defrost cycle to warm the heat exchanger, comprising:
de-energizing a compressor fluidly coupled to the heat exchanger;
delaying for a first delay period with the fan energized and the compressor de-energized;
energizing an auxiliary heater configured to warm a heat transfer medium urged across another heat exchanger in fluid communication with the compressor, before completing delaying for the first delay period;
energizing a reversing valve after the first delay period to reverse a flow of a refrigerant flow between the compressor and the heat exchanger, such that the refrigerant warms the heat exchanger;
delaying for a second delay period with the fan energized, the compressor de-energized, and the reversing valve energized; and
de-energizing the fan;
defrosting the heat pump during the defrost cycle; and
terminating the defrost cycle, comprising:
energizing the fan;
de-energizing the compressor;
delaying for a third delay period with the fan energized and the compressor de-energized;
de-energizing the reversing valve after the third delay period;
de-energizing the auxiliary heater before and/or during the third delay period;
delaying for a fourth delay period with the reversing valve de-energized and the fan energized; and
energizing the compressor after the fourth delay period
wherein:
the first delay period is about 60 seconds;
the second delay period is between about 10 seconds and about 15 seconds;
the third delay period is about 30 seconds; and
the fourth delay period is about 10 seconds or about 30 seconds.