What is a Heat Pump?
We’re asked this question a lot. In the Southern United States, air
source heat pumps are the dominant source of home heating and
cooling in a single system. However, in colder climates, they are
not as well known.
The technology in an air source heat pump is similar
to what you would find in your kitchen refrigerator. Using a simple
refrigeration cycle, refrigerators remove heat from your food and drinks
and reject it into the kitchen. This is why the coils on the back of
your refrigerator will feel warm. This process of moving heat is
achieved by taking advantage of the energy stored and released when a
refrigerant changes from a liquid to a gas.
Simply put, a heat pump can move heat into or out of
your home. In the summer time, it acts just like a standard air
conditioner and moves heat from inside your home to the outdoors. It
does exactly the opposite in the winter; it captures heat from the
outdoors and moves it into your home, keeping you and your family warm.
How does it get heat from cold outside air? Heat is
molecular motion in the air. The temperature at which molecular motion
stops, also known as Absolute Zero, is -459°F. That means that, even at
-30°F, there is plenty of heat in the air that we can take advantage of.
The properties of the refrigerant used in a heat pump
are such that it evaporates (changes from a liquid into a gas) and
condenses (changes from a gas to a liquid) at much lower temperatures
than water. In terms of the refrigeration cycle, this means that we can
take advantage of these phase changes to store and transport this heat
energy into your home.
A heat pump looks just like a central air conditioner
and most of the components are the same. On the inside of the home,
you’ll see an air handler attached to ductwork. On the outside of the
home, you’ll see the outdoor unit. Running between the outdoor unit and
the air handler is a pair of copper pipes called a ‘line set’. These are
the pipes through which the refrigerant travels between the outdoor unit
and the air handler.