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What is a Heat Pump?

By now you may have heard the words HEAT PUMP. Its everywhere. On the radio, on tv, in the papers, on the side of trucks, even on the news. Just a short few years ago we couldn't use heat pumps in Maine efficiently. That has changed. Due to changes in technology we can now use them to heat and cool our homes and businesses all year long. With this new technology and if installed correctly you too can be saving money, reduce our dependency on fossil fuels, and be more comfortable in your home. 

How Heat Pumps Work

Imagine removing the door on your refrigerator. In the winter, you position the refrigerator in a doorway, with its opening facing the outside. The refrigerator works like a heat pump, extracting heat from the outdoor air and bringing it indoors through the coils on its back. In the summer, you turn the refrigerator around so that its cool interior now faces the room. Now, it works like a heat pump to cool your house.

Heat pumps move heat from one location to another. Each pump has four main components: compressor, condenser, expansion valve, and evaporator. Heat pumps work by altering a refrigerant between its liquid and vapor phases in a closed loop.

A heat pump's refrigeration system consists of a compressor and two copper coils (one indoors and one outdoors), which are surrounded by aluminum fins to aid heat transfer. In heating mode, liquid refrigerant in the outside coils extracts heat from the air and evaporates the refrigerant into a gas. The indoor coils release heat from the refrigerant as it condenses back into a liquid. Heat pumps also have a cooling mode: there is a valve to change the direction of the refrigerant flow. This mode can also be used to defrost the outdoor coils in winter.


Andy Myer from Efficiency Maine explains how a heat pump works.




The Advantages of Air Source Heat Pumps

Low Upfront Cost

With a simple less costly installation, Air source heat pumps could become the lowest cost option for heating and cooling.

An Efficient Option

The units we provide have a great efficiency ratings. Our air source heat pumps have a heating seasonal performance factor (HSPF) over 10. Anything 8 or over is considered energy efficient. The seasonal energy efficiency rating (SEER) ratings are as high as 27 (SEER ranges from about 13-33).  

In Maine, on an annual average, a good quality cold climate air source heat pump will provide about 3 units of heat for each unit of electricity. These units can draw heat from the outside, and operate at full capacity, even when it is negative 15°F.

The pumps have 150-300% efficiency (or a “coefficient of performance” of 1.5-3.0), meaning 1 unit of energy produces around 1.5-3 units of energy. A traditional plug in heater yields 1 unit of heat for each 1 unit of electricity. These pumps perform much better than most combustion-based heating and cooling systems.

Heating and Cooling in One

Air source heat pumps provide both heating and cooling with one switch. This eliminates the need for 2 systems and increases the value of your home immediately.


Air source heat pumps have a simple design and few moving parts. This makes them highly reliable, extremely quiet, and very low-maintenance.