Air source heat pumps operate using three cycles to provide both a heating and cooling solution for your home. Whether you already own one or are looking to buy a heat pump, you should have an understanding of how these cycles work in the context of how your heat pump operates.
The heat pump heating cycle absorbs heat from the outdoor air. The steps of this process are:
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Liquid refrigerant is expanded, becoming a liquid-vapor mix.
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The liquid-vapor travels through the outdoor coil which is acting as the evaporator coil. It absorbs heat from outside, boiling and becoming a vapor.
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The vapor enters the compressor, which reduces its volume, causing it to heat up.
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The heated vapor travels through the indoor coil, transferring heat to the air in your home. A fan blows that heated air through ducts to all of your home’s living spaces.
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The refrigerant having become a liquid again, the cycle repeats.
The cooling cycle is the reverse of the heating cycle:
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Liquid refrigerant is expanded.
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This time the liquid-vapor travels through the indoor coil, which is now acting as the evaporator coil.
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The vapor travels through the reversing valve, the accumulator, and on to the compressor where it is compressed and becomes heated.
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This time the heated vapor travels through the outdoor coil, which transfers heat to the outdoor air.
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As before, the cycle repeats.
The defrost cycle begins when the heat pump heating cycle requires the outdoor coil to be defrosted. Frost builds up on the outdoor coil when temperatures are near or below freezing and there is moisture in the air. This frost buildup blocks the transfer of heat, meaning the refrigerant will not absorb any heat.
To remove the frost, the heat pump reverses into cooling mode, using the heat that is being pumped out of your home to defrost the coil. Once defrosted, the heat pump will return to the heating cycle.
If you need any further advice about heat pumps or other HVAC solutions for your home in the Dayton and Springfield area, please contact us at Ace Hardware Home Services.
Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems). For more information about heat pumps and other HVAC topics, download our free Home Comfort Resource guide.
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