Your Air-Source Heat Pump: Its Heating, Cooling and Defrost Cycles

Your Air-Source Heat Pump: Its Heating, Cooling and Defrost CyclesIf you heat with electricity, an air-source heat pump is one of the most efficient ways to stay warm through Northern Michigan’s long and cold winters. Unlike a furnace, a heat pump can keep you cool in summer, too. To do this, your heat pump employs three operating cycles.

  1. Heating – In heating mode, the heat pump’s outdoor coil acts as the evaporator coil. In this coil, liquid refrigerant absorbs heat from the outdoor air, turning into a vapor as it does so. Next the refrigerant vapor flows to the compressor, which increases the vapor’s pressure. It then flows to the indoor coil, which acts as the condenser. The blower fan blows indoor air over the hot refrigerant in the coil, warming the air. As the refrigerant cools, it condenses back into a liquid and flows back to the outdoor coil.
  2. Cooling – An air-source heat pump in cooling mode works almost exactly like a standard central air conditioner. The cooling cycle is essentially the reverse of the heating cycle. The heat pump’s reversing valve changes the direction of the refrigerant flow, allowing the heat pump to switch between heating and cooling. During the cooling cycle, the outdoor coil becomes the condenser and the indoor coil becomes the evaporator.
  3. Defrost – You may never notice when this cycle kicks in, but it’s critical for your heat pump’s efficient operation. When the heat pump is in heating mode, moisture that condenses on the outdoor coil should drip off. In very cold weather, though, it can freeze, impairing the equipment’s efficiency. To defrost the coil, the reversing valve directs hot gas from the compressor to the outdoor coil to warm it. To keep your home from getting cold, your system’s backup electric heating element warms up to heat the indoor air (or in a dual-fuel system, a gas furnace serves as the emergency heating).

Whether you need tips on caring for your air-source heat pump or guidance on choosing a new one, we can help at Team Bob’s Heating Cooling Plumbing. In and around Grand Traverse County, we provide homeowners with reliable services for furnaces, A/Cs, air quality devices, plumbing, and other home comfort equipment.

Our goal is to help educate our customers in Traverse City, Michigan and surrounding areas 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.

Image courtesy of Shutterstock

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