Heating in Southwest Florida: what you actually have and why it fails

Almost no home in Sarasota or Charlotte County has a gas furnace. Heat here comes from one of two things: electric resistance strips inside the air handler, or a heat pump running its cooling cycle backwards with strips as backup. Both spend most of the year idle, and equipment that sits idle for ten months fails differently from equipment that runs daily.

The two systems, briefly

Electric resistance heat. A bank of heating elements in the air handler, electrically identical to a very large toaster. The blower pushes air across glowing coils. It is simple, reliable, cheap to install and expensive to run: every unit of electricity produces exactly one unit of heat, no more.

Heat pump. The same outdoor unit that cools the house in summer, with a reversing valve that swaps the roles of the two coils. Instead of moving heat from inside to outside, it moves heat from outside to inside. Because it is transporting heat rather than creating it, it delivers two to three units of heat per unit of electricity in mild conditions, which is where the running-cost advantage comes from.

A heat pump has strips too, called auxiliary or emergency heat. They exist for the handful of nights when the outdoor temperature drops far enough that the heat pump cannot keep up, and for defrost cycles. In this climate they should energise rarely.

Knowing which you have matters for every decision that follows. Check the thermostat: if it offers an EM HEAT or AUX setting, you have a heat pump. If the outdoor unit runs when you call for heat, it is a heat pump. If heat arrives with the outdoor unit sitting silent, it is strips.

How much heating this region actually needs

Context explains most of the design decisions. Winter here means overnight lows in the 50s for much of January and February, with a handful of nights each season dropping into the 40s and an occasional intrusion below that. Daytime highs recover into the 70s. The heating load is small, concentrated in a few hours before dawn, and spread across perhaps six weeks.

That has two consequences. First, equipment is sized for the cooling load, which is far larger, and the heating capacity is whatever comes with it. Nobody in Southwest Florida sizes a system around January. Second, the economics of efficient heating are weak on their own: a system that saves half the running cost of a load this small pays back slowly, which is why strip heat remains common in housing stock that would never see it further north.

It also explains why heating problems get discovered late. A fault that developed in March goes unnoticed until December, and by then nobody connects it to anything. The failure did not happen on the cold night. It was simply revealed by it.

The burning smell on the first cold night

Every year, the first genuinely cold evening produces a wave of calls about a burning smell. In most cases nothing is wrong. Dust settles on heating elements over ten months of disuse and burns off in the first few minutes of operation. The smell should fade within fifteen minutes and not return on subsequent cycles.

What is not normal: a smell that persists past the first cycle, an acrid plastic or electrical odour rather than a dusty one, visible smoke, or a smell accompanied by a breaker trip. Those point at insulation on a wire, a failing element, or an overheating connection, and they justify shutting the system off at the breaker and calling.

The way to avoid the ambiguity entirely is to run the heat for twenty minutes in October, with the windows open, on a day when nobody needs it. Dust burns off on a schedule you chose, and if something is genuinely wrong you find out with weeks of lead time instead of on the coldest night of the year.

What breaks on a heat pump

Reversing valve. The component that decides whether the system heats or cools. When it fails or sticks mid-position, the most common symptom is cold air from the vents on a call for heat, sometimes with the outdoor unit running normally. Because it is brazed into the refrigerant circuit, replacement means recovering the charge and is a significant job.

Defrost control. In heating mode the outdoor coil runs colder than the outdoor air and can accumulate frost. The defrost board periodically reverses the cycle to melt it, which is why an outdoor unit sometimes steams on a cool morning. A failed board leaves the coil iced and capacity collapses. In Southwest Florida the reverse fault is more common: a board that calls defrost far more often than conditions require, quietly running the strips each time.

Auxiliary heat locked on. The most expensive failure that produces no complaint at all. A faulty outdoor sensor, a miswired thermostat or a stuck relay energises the strips whenever there is a call for heat, so the house is warm and the heat pump advantage disappears. It shows up on the power bill, not in the comfort.

Sensors and thermostat wiring. Heat pumps depend on more inputs than a cooling-only system. A failed outdoor sensor or a thermostat configured for the wrong equipment type produces behaviour that looks mechanical and is not.

What breaks on strip heat

Sequencer. The relay that brings elements on in stages rather than all at once. When it fails, either nothing comes on or one stage does, and the house heats slowly or not at all.

Element burnout. A resistance element eventually opens like a filament. With several elements in a bank, losing one reduces output without eliminating it, so the complaint is usually weak heat rather than no heat.

High-limit switch. A safety that cuts the elements when air temperature in the plenum climbs too high, almost always because airflow is restricted. A dirty filter or a closed-off return produces short cycling on the limit, and a limit switch tripping repeatedly is a symptom of an airflow problem rather than a heating one.

Blower issues. Elements without airflow trip the limit immediately. Any heating complaint that also involves weak airflow is an airflow investigation first.

Getting it looked at sensibly

Heating in this region has a short season and a busy start. The sensible time to have the heating side checked is autumn, at the same visit as the post-summer service, when the technician can energise each stage, measure amp draw on the elements against their rating, confirm the reversing valve shifts, and verify that auxiliary heat only comes on when it should. That last check is the one that pays for itself.

Note that companies here almost never advertise heating separately, so a search for furnace repair in North Port reaches the same firms that handle cooling. That is not a marketing quirk. It is the same equipment, and a technician who knows the air handler knows the heat.

When you call, be specific about what happens: whether the outdoor unit runs, whether air comes out warm or cold, whether the thermostat shows AUX, and whether a breaker tripped. Those four facts narrow the diagnosis considerably before anyone arrives.

Frequently asked questions

Why does the air from a heat pump feel cool even though it is heating?

Supply air from a heat pump typically runs in the 90s °F, warmer than a room but cooler than skin, so it feels cool on your hand. Strip heat produces much hotter air, which is why people switching to a heat pump often assume it is underperforming when it is not.

Should I use EM HEAT when it gets cold?

Only when the heat pump is not working. Emergency heat bypasses the compressor and runs on strips alone, at several times the running cost. It is a fallback for a broken system, not a setting for a cold night.

My heating bill was enormous after one cold week. Is that normal?

For strip heat, unfortunately yes. For a heat pump, a large jump suggests the auxiliary heat was doing work the compressor should have done, which is worth having checked.

Is it worth replacing strips with a heat pump?

Rarely on its own, given how few heating hours this climate has. It becomes worth it when the air conditioning is being replaced anyway, because the incremental cost of a heat pump over a cooling-only system at that moment is small.

Current as of September 2026.