Steam From Your Heat Pump

“On cold days, my heat pump heating and air system has steam coming out of it. Why is that?”

We get this question quite a bit, especially when it gets really cold. We often get calls saying “My unit is smoking, my unit is on fire”. When you have a heat pump (package or split) it goes through what is called a defrost cycle because when it pulls as much heat as it can from outside it gets really cold frosting the outside coil.

When in the defrost cycle the strip heat comes on to keep you warm inside because in this cycle it melts the frost off of the unit. Technically it is reversing back in to AC mode but now it is pushing the hot air back out of it for melting it off. So when that happens and its cold outside, its normal to see steam rising up. Your unit will turn on that strip heat so you don’t get cold inside and then reverse into AC mode, melts it off, turns the strip heat on and then goes back into heating mode. That will probably happen every 30–60–90 minutes depending on where your setting is. This will also depend on where your sensor is on that outside coil to switch it off. You can either have a timer or a sensor. The sensor will read it and realize that “hey I need to go into defrost cycle” where the timer is just like every 30–60–90 minutes it will switch over automatically.

Now if you go outside and you have a block of ice on your unit, then you have a problem. You will need to call somebody to get that checked out. You could have a problem with the board not signaling it that it needs to go into defrost and there for the frost just keeps building up until you have a big block of ice. Or you could have a problem with the reversing valve. It could really be a number of things that could be wrong. But when you see that you really need to call a professional because that block of ice is just going to keep building up and your strip heat will just continue to run. You might not know there is a problem until all of a sudden you get that crazy high electric bill.

Remember too, the first time that strip heat comes on, if you haven’t had maintenance and there is dust build up , you will kind of get that dust burning smell and then you look outside and see the steam coming off the unit. It’s ok. It’s just that dust burning off from the summer time. Just keep an eye on your unit and do regular maintenances.

Your friend in comfort and energy savings,

Derek Cole

Derek Cole is the General Manager of One Hour Heating & Air Conditioning®, an independently owned and operated franchise based in Laurinburg, North Carolina since 1953. He has more than 14 years of experience in the HVAC industry and has created two You Tube broadcasts, The Comfort Experts and #AskDerekCole, filled with tips and tricks on saving energy and being comfortable. He was named the Top 40 under 40 in the HVAC industry by the News magazine and featured in Entrepreneur Magazine Franchise Player Spotlight