How do Heat Pumps Work?

How do Heat Pumps Work?

Here in the Ohio Valley winters are often unpredictable. Some years we have mild winters with barely a dusting of snow and other years we are blasted with the ice storm of 2009. Also in Louisville, KY we never seem to know when winter is going to come or how long it’s going to last. At the end of March 2007 we saw temperatures in the high 70’s and a few days later on April 3 temperatures dropped into the 20’s and brought us snow!

Confused by the Ohio Valley weather patterns? Well so is your heat pump! A heat pump is like an air conditioner that cools the indoors and heats the outdoors by pumping heat from inside the home out. When it’s cold outside the heat pump switches into reverse and pumps heat into the house. When the weather is changing from day-to-day like it sometimes does in Louisville then the heat pump has to change with it. Therefore it is important to keep you heat pump in good working order.

A Heat pump contains an outdoor expansion valve that reduces the pressure of the refrigerant in the outdoor coil until the coil is much colder than outdoors. This coil is actually warmed by the cold outdoor air. It is interesting to note that a heat pump coil can reach temperatures as low as 20F below zero. After picking up as much heat as possible from the outdoors, the heat pump compresses the refrigerant to very high pressures which raises the temperature to as high as 130 degrees. This warm air then flows through the home to get little feet warm and toasty!

This super cooling of the outdoors coil does create one little problem. Although cold winter air holds little humidity, the super cold heat pump coil turns that little bit of water vapor into frost. After an hour or two, the heat pump coil will collect enough frost and ice to block airflow. Reduced airflow results in a colder coil and more frost – a real snow-ball effect. This snowball slashes efficiency and greatly damages the compressor.