But you might look out a window one cold morning and see something alarming: smoke rising off the heat pump’s outside cabinet. That doesn’t look good! Are the heat pump motors burning out? Is the unit on fire?

Before calling an HVAC contractor in Clifton, NJ to rescue your heat pump, read about the most likely explanation for what you’re seeing. In most cases, you don’t have a problem—the heat pump is working as it should.

We ask this because what you’re seeing is something that’s normal for heat pumps during winter operation. When people become panicked about seeing what looks like smoke rising from the outside cabinet, they probably have never seen the heat pump running during winter.

That smoke isn’t smoke at all. It’s steam. What’s happening is the heat pump is going through the defrost cycle, a part of its operation that doesn’t happen when it’s in cooling mode.

You’re probably already aware that your heat pump is a refrigerant-based system that works like an air conditioner that can also be run in reverse, so instead of removing heat from indoors and releasing it outdoors, it removes heat from outdoors and moves it indoors. Pretty basic operation.

However, there’s a potential negative side effect of this, which is that water collects along the refrigerant coil when the refrigerant evaporates to draw heat from the outdoors. During warm weather, the evaporation occurs along the indoor coil, and the moisture collecting on the coil simply drips away into the condensate pan and drain. (This is why you sometimes hear water dripping inside the heat pump in summer.) But during cold weather, the moisture gathers on the outdoor coil—and if the temperature is below freezing, the water will turn to ice along the coil.

Too much ice restricts the coil from absorbing heat, but the heat pump has a way to overcome this. The system will periodically switch into defrost mode where it runs refrigerant the opposite direction so the coils release heat again—just enough to melt the ice and get back to standard heating mode.

The “smoke” you see coming from the heat pump on those cold days is steam from the ice on the coils melting. It means the heat pump is working the way you want it to! If the defrost cycle fails, the heat pump will soon be unable to provide any heat to the indoors because of the ice.

If you do notice your heat pump losing its heating capacity or rapidly turning on and off, please call us for help to handle any repairs. We have just one priority: happy clients every time, no matter what it takes.

Advanced Mechanical Services serves the Northern New Jersey Area. Reach out to us for any heat pump repairs or other heating services you might need.