What is a Ductless Heat Pump Anyway?

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  • Heat Pumps
  • Heating your home or business is a major expense and figuring out which type of heating system is best for you can be a daunting decision, especially when the technology is always evolving.  We’re all familiar with the old fashioned fuel-oil furnaces – fuel goes in, gets burned up, heat comes out – but how exactly does a ductless heat pump work?  And how is it going to save you so much money?  What is a ductless heat pump, anyway?

    A couple weeks ago we talked about air-to-water heat pumps and how they can both heat your home and your water, but today let’s demystify the science behind these mysterious ductless heat pumps (one type of which is the mini split heat pump we use in our own home).

    The Basics

    A ductless heat pump has two components:

    • An outdoor unit which extracts energy from the cool air outside.
    • And an indoor unit which transfers that energy into hot air inside.


    It may seem counter-intuitive to get warmth from the cold air outside, but air, even very cold air, contains energy and an air-source heat pump takes that energy and turns it into heat. The unit runs on electricity, just like your refrigerator – in fact, the technology involved is very similar to that of a refrigerator or freezer, only with the components arranged differently.  (Which is part of why a company with “refrigeration” in our name is in familiar territory when it comes to heat pumps.)

    The units are called “ductless” because there is no duct work involved – and no loss of energy as the heat travels through the ducts.  The interior unit releases heat directly into the home.

    The technology involved is very similar to that of a refrigerator.

    How Does It Work?

    Both the indoor and outdoor units contain heat exchanger coils.  A refrigerant is pumped through the coils.  When the liquid refrigerant is at a low temperature and low pressure, it passes through the outdoor heat exchanger coils and the ambient heat causes the liquid to boil and change into a gas.  The heat energy from the outside air is absorbed and stored in the now-gas refrigerant as latent heat.  An electric pump compresses the gas, which increases the temperature.

    The refrigerant is piped inside, where the gas passes through a pressure valve into the interior unit’s heat exchanger coils.  In that unit, the hot refrigerant gas is condensed back to a liquid and the stored latent heat is released as hot air and disbursed via a fan.  The now cool liquid refrigerant returns to the outdoor unit to begin the process again.

    Many heat pumps also have a cooling mode and can operate as air conditioners during warm weather.

    The interior unit releases heat directly into the home.

    Find the Heat Pump That’s Right For You

    And that’s all there is to it.  A heat pump draws heat from the cold air outside and releases it as warm air inside.

    Different heat pumps have different temperatures at which they produce heat most effectively and different capacities for the spaces they can heat.  As lifelong Alaskans with experience using these products in our own homes, we would love to help you find the one that is right for yours.