In Episode 101 of the Ask Derek Cole Show, host Derek Cole answers two listener questions about heat‑pump behavior in very cold weather. He explains that a heat pump will run continuously when outdoor temperatures are below freezing because it must work constantly to satisfy the indoor thermostat setpoint; the start‑up surge uses more power than steady‑state operation, so long run times are more efficient, much like highway driving versus stop‑and‑go traffic. He describes how the system may enter auxiliary (emergency) heat or a defrost cycle, during which the outdoor fan stops while indoor fans and electric strip heaters run to keep the house warm. Cole warns against the common misconception of manually switching the thermostat to emergency heat in cold weather, noting that electric heat is roughly three times more expensive than heat‑pump heat and that the outdoor fan’s inactivity is normal when the system is in those modes. He advises keeping the thermostat on normal heat mode, allowing the heat pump to run with supplemental electric heat only as needed, and only using emergency heat if the outdoor unit is completely covered in snow or ice. The episode concludes with a reminder to hashtag questions with #AskDerekCole.
Questions this video answers
Yes. In below‑freezing weather a heat pump will run continuously to meet the thermostat setpoint. Long run times are more efficient than frequent start‑stop cycles, similar to highway driving versus stop‑and‑go traffic. The unit may also run auxiliary heat and a defrost cycle during this time, which is normal.
The outdoor fan stops when the system is in auxiliary (emergency) heat or a defrost cycle. This is normal. Keep the thermostat on normal heat mode; the heat pump will run with supplemental electric heat as needed. Switch to emergency heat only if the outdoor unit is covered in snow/ice.
Chapters
Hey, on this episode we talk about why is my heat pump running all the time and my outdoor fan is not working, but I still have heat in the home. You ask your comfort and energy questions and they get answered. This is the Ask Derrick Cole Show. Hey, this is Derrick Cole. Welcome to episode 101 of the Ask Derrick Cole Show. And yes, we are back. We have been on vacation. Carolina's been so busy with inventory, and you know, this is, this is Carolina's side hustle. You know, her real job is not doing this, which is filming the show, so I had to kind of wait on that. Um, it's been a good vacation, very cold weather, so that's been nice. That's all I got.
Is my heat pump supposed to run non-stop? It's ran all morning.
Yes, with the below freezing weather we've had the last few days, the heat pump is going to run all the time. I mean, think about your heat pump and what you do in your car. I had a lady come up here and see me, and this was in AC mode, but it applies to heat. She said, my AC won't stop running. It was like 95 degrees outside. I said, well, where did you come from? She said, I live right down the road. I said, well, how many times did you turn the AC off in your car on the way here? She said, I didn't. I said, why? She said, it would have got hot. I said, exactly, your house is the same way. So whether it's 95 degrees or 20 degrees, if you have a heat pump or a gas unit, it's not going to turn off because it's trying to satisfy that thermostat in the house. So regardless if you have it set on 64, 65, 75, it is going to try and satisfy that thermostat. So the unit is going to keep running. When it's the way it's been, which is 20 degrees outside, it takes a lot to keep up with the home demand. So the unit is going to run a while. It's going to run the emergency heat as a backup heat source. It's going to run the defrost. So all that's going to happen. So it's not abnormal for it to run all morning long, especially when it's, you know, 13, 15, like it has been around here the last few days. So that is completely normal. Don't worry about it. The unit is made to run. Don't be concerned that maybe the unit is wearing out. I've had that before. People say, is it supposed to run this long? Because I'm worried. Don't worry about the unit. It's a machine. It's supposed to keep you comfortable. So it's going to run until that thermostat is satisfied, and then it's going to say, okay, if it's A newer unit is going to say, I need to keep running because even though the thermostat is set on 75 and it's 75 in the house, if I turn off, it's going to drop to 74, so I turn right back on. So it's not going to even turn off because it knows what the house is, it knows what the setting is, and it knows how to stay comfortable and be efficient. So it's more efficient for the unit to run for long periods of time than it is for it to turn on and off, on and off, on and off, related to miles per gallon. It's a lot more efficient to go from here to go on I-95 to take a trip to DC than it is to go up number 1, stop-and-go traffic, stoplights, right? You get more miles per gallon if you just go on the interstate. The unit's the same way. It's made to run. It's made to run for periods of time. So it's better for it to run and then turn on and off. And that's what's going to happen if you want it to not run all the time. It's going to turn on and off, on and off, on and off. So you're better off than it running for a period of time. Does that make sense? Because it's, it's more the most power that unit pulls is when it starts, just like your car. So the longer the runtime, the better, because you're saving energy by actually starting and running versus starting, stopping, starting, stopping. It's actually more efficient for it to keep running.
My fan on my outdoor unit isn't running, but I have heat in the house.
You have a heat pump and it's going on auxiliary only. So the mistake some folks make is they've been told that it's more efficient when it's cold outside to turn their thermostat to auxiliary heat or emergency heat and not heat pump heat. So when it goes into that mode, the outdoor fan will stop running outside and the indoor fan and the strip heater run inside to keep you warm. That'll also happen when it's going into a defrost cycle. So if you haven't done that and you just have it on heat, Your heat pump will run, and when it goes into defrost, that fan will stop, the electric heat will come on, and it will defrost that coil, which you'll see that steaming coming up when it's really cold in the morning. So that's normal. Um, but it is more efficient for you, even on cold days like we've had, to have that heat pump running, not to switch it over to emergency heat. The only time I would even recommend doing that is if the outdoor unit is just covered in snow and ice and there's— it's not doing anything. But we don't have that here, so it's more efficient to run heat pump with electric heat than it is to only run electric heat. I think Scott told me that electric heat is like 3 times more expensive than heat pump heat, so The electric heater will run to supplement the heat pump, but it won't run all by itself, which is what you're doing when you switch it over to emergency heat. So the outdoor fan not running, that's why that's happening. Make sure your thermostat is on heat and not set over to emergency heat because some people have been told that's what they need to do, and that's completely wrong information. All right, this is episode 101 of the Ask Derrick Cole Show. Be sure to hashtag your questions #AskDerrickCole and we will get them on the show. This feels good, right? Like back into action, back in normal. We'll get them on the show.
