Can My Furnace Freeze? | Winters® Home Services

January 19, 2022

In the dead of winter, the last thing you want is to be caught without heat. Much the same way, not having air conditioning during summer months can be a truly miserable experience, the last thing you want is for your climate control system to freeze over. Air conditioners can freeze, but does that mean your heaters can do the same? After all, your heater operates in frigid conditions that can often dip well below freezing, so it only seems logical that there’s a chance it could ice over and fail.

Do you have to worry about this problem, and if so, how can you avoid it?

As you might expect, the answer is a little complicated, but generally pretty easy to understand. If you have a gas or oil-burning furnace, your heater can’t freeze. These systems burn fuel to generate heat, and they don’t have to worry about collecting thermal energy from elsewhere. Therefore, the only way you can actually cause one of these systems to freeze over is if it is so cold that your oil or gas freezes itself (and for perspective, natural gas freezes at -297 degrees Fahrenheit, well below temperatures that occur naturally on Earth.)

If you have an electric furnace, then you’re also okay as well. Electrical transmission equipment can begin to experience problems at lower temperatures, but your heater itself will not freeze over. The heating elements themselves are not exposed to the cold, and should continue to operate uninhibited as long as power remains connected and stable (however, they may overheat if they don’t receive strong enough airflow.

If you have an electric heat pump, then you have a little bit more to think about. Heat pumps rely on thermal energy in the outdoor atmosphere to warm your home, and they collect it by creating significantly colder conditions that draw in thermal energy. They’re generally extremely efficient at doing so with temperatures down as low as the teens, but they do eventually start to lose efficiency.

However, heat pumps that create such tremendously cold temperatures do run the risk of freezing over. Because your outdoor coil will have to get extremely cold to collect the heat it needs, any water vapor in the air at all runs the risk of instantly condensing and freezing when coming in contact with your outdoor coil. Thus, humidity is a natural enemy for heat pump systems. Typically, winter means dry air and that means this isn’t as much of a problem.

However, all heat pumps will eventually need to give the coil a rest and melt any accumulated frost and ice. They generally do this by running an occasional “warm-up” cycle. These cycles allow the ultra-cold outdoor coil to come back up in temperature, thus removing any potentially collected frost and ice that may have accumulated.

Generally, any heat pump heating system will have a number of built-in safety checks and mechanisms in place to prevent a heat pump from freezing over by kickstarting a defrosting cycle when necessary. A frozen heat pump is more than just inoperable—it could also be damaged. Therefore, these systems are built to monitor themselves and avoid freezing over. However, ideally should still do your part to prevent your system from freezing.

First, make sure you regularly change your system’s air filter. Heat pumps are designed to work best when they get the greatest level of heat transfer, and that can generally only be accomplished when a system receives the maximum amount of airflow. Second, having your heat pump tuned up and properly maintained will help you avoid an unwanted freeze problem or other issue that could prevent your heat pump from working properly when you need it the most.

Pick up the phone and call the experts at Winters® Home Services at 617-221-5899 today to schedule a service appointment and let us keep your heat pump in great condition all winter long!