We are often asked about heat pumps when we talk with homeowners in the Omaha metro area about upgrading their older HVAC system. Homeowners commonly ask us what is a heat pump? A heat pump (HP) is a compression refrigeration system similar to a traditional residential air conditioner. However, the HP has a few extra components that allow the unit to reverse the refrigerant flow on cold days. So in normal air conditioning mode, heat is removed from the indoor coil and expelled in the outdoor coil. Normal air conditioning mode cools the home.

Heat Pump In Heating Mode

In heating mode, the refrigerant flow changes directions. Heat is pulled from the outside air and is absorbed in the outdoor coil. Then the heat is transferred to the indoor coil. Home air circulates over the indoor coil to warm the house. The indoor coil relies on the blower motor of a traditional gas furnace or an electric air handling unit to circulate the air.

Accurate Heating & Cooling is an established HVAC contractor. We have been serving our greater Omaha customers for over 20 years. And we service and install HPs. We have an A+ rating with the Better Business Bureau. And check out what our customers are saying about us on our Customer Testimonials page. Call us today at 402-238-2425 to schedule an appointment.


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Illustration of Residential Heat Pump Heating A Home

An illustration of a HP installed in a residential home is shown below. The image is from the DIY experts of The Family Handyman Magazine at their website www.familyhandyman.com.


Diagram of residential heat pump operating in heating mode

The image shows the outdoor unit absorbing heat from the outside air. The hot refrigerant carries this heat to the indoor coil. The indoor blower forces air over the hot indoor coil warming the house.

The US Department of Energy offers some general information on the advantages and disadvantages of heat pumps. Check out this DOE website for more information.

Heat Pump Operation In Very Cold Temperatures

The thermometer in the image shows that the HP will operate above a certain temperature. The image shows the cutoff temperature as 35F. Different HPs are able to operate at different outside temperatures. However, this 35F is a good average temperature to go by. When the outdoor temperature goes below the cutoff temperature for the HP then the auxiliary heat comes on. If the HP is designed to operate in ultra cold temperatures, the amount of heat output is reduced. The auxiliary heat can be electric heat elements inside an air handler. Or the auxiliary heat can be a natural gas furnace.

The video below expands on how outside temperature affects the operation of the heat pump. This video is from an organization in Virginia called the Community Housing Partners.

How The Heat Pump Reverses Refrigerant Flow

The heat pump has an outdoor unit, a refrigerant line set, and an indoor unit similar to a traditional air conditioner. However, the HP has the following additional components.

  • Reversing valve
  • Additional metering device
  • Defrost control board
  • Refrigerant accumulator
  • Additional wires in the thermostat wire
  • Heat pump compatible thermostat

Reversing Valve

The reversing valve is the component that allows the HP to change the direction of refrigerant flow. For most units, when the reversing valve is energized, the HP is in air conditioning mode. And when the reversing valve is de-energized, the HP is in heating mode.

Metering Device

The second metering device is required because when the HP is in heating mode, the outdoor coil becomes the evaporator. And a metering device is required to meter the flow of refrigerant to the evaporator. So a HP has one metering device at the indoor coil and a second metering device at the outdoor coil.

Defrost Control Board

The defrost control board determines when the HP needs to defrost. When the HP is in heating mode, the indoor coil is hot and the outdoor coil is cold. The outdoor coil can be below the freezing temperature on cold days. This means that ice can form on the outdoor coil. The ice can block air flow across the coil. The defrost circuit warms up the outdoor coil to melt any ice accumulation. The defrost cycle happens automatically. During the defrost cycle, water vapor can be seen rising from the outdoor unit as any accumulated ice melts.


An accumulator is a cylinder that maintains a reservoir of refrigerant charge. The HP requires a different amount of refrigerant during heating mode and cooling mode. The accumulator stores the additional refrigerant charge required for normal operation depending on seasonal needs.

Heat Pump Compatible Thermostat

Heat pumps require a thermostat that is heat pump compatible. And recall that the heat pump has additional components over a standard air conditioner. In order to properly control the additional components and features of a HP, the thermostat wiring needs to have more wires than a traditional air conditioner requires.

The image below is of a heat pump reversing valve

Heat Pump Reversing Valve Image


In the video below, a description is provided on how a reversing valve operates. This video is from the greyfurnaceman series and is titled “how does the heat pump reversing valve work”.


Various components of the outdoor unit of a heat pump are identified in the image below.

Components of Heat Pump outdoor unit


An image of a heat pump defrost control board in the outdoor unit is show below.

Heat Pump Defrost control board in outdoor unit


Water Vapor Rising From Heat Pump During Defrost Is Normal

When the HP is in defrost mode during freezing weather, water vapor will be seen rising from the outdoor unit. This is part of the normal defrost operation of the unit.

Vapor coming off heat pump during defrost in very cold weather


Trane offers a full line of HPs for residential use. They range from moderate efficiency basic units up to ultra high efficiency modulating units. Trane Heat Pump Consumer Brochure for more information.

Weather it is a new heat pump you are looking for or for repair work to an older HP, we are your trusted heat pump experts in Omaha. Check out our furnace and heat pump page for more information on our product offerings. In the photo below, JJ is brazing a replacement component in a HP unit.

heat pump repairs to outdoor unit


The heat pump will cool your home in the summer just like a traditional air conditioner does. HPs are rated in tons of refrigeration just as traditional air conditioners are. And the HP will also dehumidify the air just like an air conditioner. The same air filter options for heat pump systems are available as traditional heating systems. There are many regular maintenance items that homeowners can perform to keep their HPs operating all season long.


If you are considering replacing an older heat pump, give Accurate Heating & Cooling a call today. Our office number is 402-238-2425. We can also talk with you about the advantages of replacing your air conditioner with a HP. There are also mini split heat pumps available as well that have some great advantages for certain applications. Geothermal ground source heat pumps also offer a some great advantages to home owners. Schedule a seasonal clean and check to keep your equipment running all season long. Ever wonder about the benefits of having annual furnace maintenance done?


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