A heat pump is the most energy efficient type of electric heat on the market, particularly for the southern United States. When installed properly, air source heat pumps can deliver one‐and‐a half to four times more heat energy during the winter than they consume.
So how does a heat pump work? A heat pump is not much different than a car in that it can go forward or reverse. In the winter, an air source heat pump gets heat from the outside air and brings it into your home. In the summer, the unit works in reverse and takes heat from your home and dumps it outside.
Air source heat pumps work very efficiently when the outdoor temperature is in the 500F range. As the outdoor temperature drops, the heat loss of a home is greater and the unit needs to operate for longer periods of time to maintain a constant indoor temperature.
Around 37 degrees many air source heat pumps reach what is called the balance point. At or near this temperature the unit needs to run constantly to produce enough heat to maintain a comfortable indoor temperature.
As the outdoor temperature continues to drop, the heat pump needs help from traditional electric resistance heat coils (supplemental, auxiliary or emergency heat). These coils resemble the glowing wires inside your toaster and consume vast amounts of electricity as they burn to keep you warm. Your thermostat will most probably have a light that comes on when this happens. It is usually labeled as emergency or auxiliary heat.
Despite setting your thermostat to 68 degrees, there is a very good chance your heat pump can’t reach that temperature…this can vary from house to house based on factors like insulation levels and air infiltration. The result is your heat pump has to run continuously which causes your monthly bill to add up quickly since heating/cooling accounts for around 50% of your monthly usage.
Under normal conditions, the cost of running a heat pump for a JOEMC member is around 30 to 35 cents per hour. When operating in the auxiliary/emergency heating mode, that cost goes up to around $1.30 per hour.
If your heat pump is operating in auxiliary/emergency mode without due cause (outdoor temperatures are above freezing or no drastic adjustment to your thermostat), it is possible that your system is malfunctioning. You should contact a licensed heating and cooling professional and have it serviced immediately.