When the first real cold front reaches Sarasota and Manatee County and you switch the thermostat to HEAT for the first time since last winter, most of what happens in the first half hour is normal. A short burning smell, air that feels lukewarm on your hand, and a cloud of steam rising off the outdoor unit on a cold morning all have ordinary explanations. A few things do not, and this is how to tell them apart.
Most homes here heat one of two ways. A heat pump is the same outdoor unit that cooled the house all summer, running in reverse. Electric heat strips are coils inside the indoor air handler that glow hot like a toaster. Many heat pumps have strips as a backup. Either way, the system has spent eight or nine months doing nothing but cooling, and the heating side may only run a handful of nights a year.
What should I check before the first cold night?
Do this on a mild afternoon, not at 10pm when it is already in the 40s outside.
- Thermostat: set it to HEAT and raise the temperature two or three degrees above the room. Within a few minutes you should hear the indoor blower and, on a heat pump, the outdoor unit start.
- Filter: a clogged filter starves heat strips of air, and they get hotter than they should. If you can’t see light through it, change it.
- Breakers: the indoor air handler, which powers the heat strips, and the outdoor unit usually have separate breakers. The strips draw a lot of current, so a tripped indoor breaker is a common reason for no heat at all.
Our article on an AC that runs but won’t cool walks through the thermostat and breaker basics in more detail, and they apply the same way in winter.
If you are a seasonal resident opening the house for the winter, or you had a new smart thermostat put in over the summer, test the heat early. A thermostat replaced in July may never have been asked to heat, and if the heat pump wiring setting is wrong, the system will cool when you ask for heat.
Why does it smell like something is burning?
Dust settles on heat strips and inside the ductwork over the months they sit unused. The first time the strips heat up, that dust burns off. It smells dusty and toasty, it is strongest in the first few minutes, and it fades within 15 to 30 minutes. You may notice it faintly again the next time or two. Opening a window helps.
That is different from a smell of hot plastic, rubber or electrical insulation, a sharp acrid smell, a smell that gets stronger instead of weaker, or anything you can see as smoke. Those point to wiring, a motor or a component overheating. Turn the system off at the thermostat, and if there is smoke, switch off the breaker too. A heat pump’s outdoor unit burns nothing, so any burning smell coming from outside is electrical.
Why does heat pump air feel cool?
A gas furnace blows air that is noticeably hot. A heat pump blows air that is warm, often somewhere around 85 to 100 degrees on a typical Florida winter night. That is close to or below the temperature of your skin, so moving air at that temperature can feel cool on your hand even while it is warming the house. Heat pumps make up for it by running longer, steadier cycles.
The real test is the room, not your hand. Put a kitchen thermometer in a vent after the system has run ten minutes. If the air is clearly warmer than the room and the house is slowly warming up, it is working. Our heat pumps page explains more about how they move heat rather than make it.
If the air at the vents is colder than the room while the outdoor unit runs, the system may still be cooling. Every heat pump has a reversing valve that switches it between modes, and after a long summer in the cooling position it can stick. Turn the system off for five minutes, then back on to HEAT once. If it is still blowing cold, leave it off and call, because running a heat pump in cooling mode on a cold night only makes the house colder.
Why is the outdoor unit steaming?
On cold, damp mornings, frost builds up on the outdoor coil. Every so often the heat pump switches into defrost mode to melt it. The outdoor fan stops, you may hear a whoosh, and a cloud of steam rises off the unit while water drips underneath. Indoors, the air may feel cooler for a moment or the heat strips may come on to cover the gap. It usually lasts a few minutes, up to about ten, and then the unit goes back to heating. Inland areas such as Myakka City often see the coldest mornings, so defrost cycles there are more common.
What is not normal: a unit encased in solid ice, ice that never clears between cycles, a fan that scrapes or won’t turn, or steam that smells like burning.
What does EM HEAT do, and why does it cost more?
EM HEAT, or emergency heat, shuts the heat pump off and runs the electric strips alone. The strips turn electricity directly into heat, while a heat pump moves heat that is already in the outdoor air. At our winter temperatures, the strips can use roughly two to three times the electricity for the same warmth.
Emergency heat is meant for when the outdoor unit has failed and you need to stay warm until it is repaired. Left on by accident, it shows up on the next power bill. An AUX light during normal heating is different: it means the strips are helping during defrost or after a big jump on the thermostat. Raising the setting two degrees at a time keeps the strips from coming on more than they need to.
When to stop and call
- You smell hot plastic or electrical burning, or see smoke
- The dusty smell is still strong after the first hour
- A breaker trips again after one reset
- The vents still blow air colder than the room after one restart
- The outdoor unit stays iced over or won’t run while the indoor blower does
- The house only stays warm on EM HEAT
It also helps to have the system looked at before the cold arrives. We recommend maintenance twice a year, before summer and again in fall, and our maintenance plans cover the electrical connections and thermostat calibration that heating depends on.
If something on that list sounds familiar, our heating repair and installation page covers the heat pump and heating service we offer across Sarasota and Manatee County, and you can call or schedule from there.
Heat still not right?
We answer the phone 24/7, including nights, weekends and holidays. Upfront pricing before any work starts.