What does the emergency heat setting actually do?
It locks out the outdoor unit and runs the air handler's electric resistance strips — 5 to 20 kW — as the only heat source.
They're the same strips your system already uses for backup. The difference is that in EM HEAT there is no heat pump helping; the strips carry 100% of the load at 100% of the cost. It exists so you have some heat when the outdoor unit can't run — not as a "cold day" setting.
What's the difference between emergency heat and auxiliary heat?
AUX is automatic: the thermostat adds the strips alongside the heat pump when it can't keep up. EM HEAT is manual: strips instead of the heat pump.
AUX engages below about 35–40°F, during defrost cycles, or when you raise the setpoint 3°F or more at once. "AUX" flashing on a cold morning is normal. "EM HEAT" showing in March is a bill.
When should I use emergency heat in Orlando?
Three cases: the outdoor unit is dead, the outdoor unit is a block of ice that won't defrost, or a technician told you to while a part is on order. That's it.
Not because it's cold. Not because the air feels cool — heat pump air is supposed to feel cool. If the outdoor fan is spinning, leave the thermostat in Heat and let AUX do its job.
How much does emergency heat cost per hour?
About $1.50 an hour for a typical 10 kW strip pack, versus $0.45–$0.75 for a 3-ton heat pump heating the same house.
The math: 10 kW × 1 hour = 10 kWh, at roughly 15¢/kWh = $1.50. A 3-ton heat pump draws 3–5 kW doing the same job — $0.45–$0.75. Run EM HEAT 12 hours a day through a cold week and it's about $125 extra, which is the "why is my bill $300?" call we get every March.
The thermostat stays in emergency heat until a person switches it back. The most common bill spike we diagnose is a setting someone flipped during a cold snap in January and forgot.
Why did my power bill spike in winter?
Five causes, in the order we find them: EM HEAT left on; strips stuck on; the heat pump not running so the strips carry everything; big thermostat setpoint jumps; leaky ducts.
- EM HEAT left on — free fix. Switch to Heat.
- Strips stuck on — a failed sequencer or relay ($150–$350) holds the strips on even when the heat pump is fine.
- Heat pump not running — a contactor ($150–$350), capacitor ($150–$400) or refrigerant leak ($400–$1,600) leaves the strips doing all the work.
- Setpoint jumps — raising the thermostat 5°F every morning calls the strips every morning. Hold a steady temperature instead.
- Leaky ducts in an unconditioned attic — pulling in cold outside air the strips then have to heat.
How do I know if my heat strips are stuck on?
The outdoor unit is off but the vents are hot. The air handler breaker is warm. The bill is up 40% or more with no setting change.
A stuck sequencer or relay is a $150–$350 fix. Leaving it is $100+ a month. Full pricing: heating repair cost in Orlando.
Does emergency heat work if the heat pump is broken?
Yes — that's its purpose. It will hold an Orlando house in the 60s on a 35°F night.
It will not hold 72°F, and it shouldn't be the plan for more than a few days. Same-day heat pump repair is cheaper than a week of strip heat.
Should I turn emergency heat off after a repair?
Yes, immediately. Our technicians reset it before they leave — if someone else's didn't, switch the thermostat back to Heat now.
Then watch the thermostat for a day: if "AUX" shows constantly on a mild day, the heat pump isn't pulling its weight and the repair isn't finished. A $89 heating tune-up in November checks the strips, the sequencer and the changeover before you need any of them.
Quick answers
Is emergency heat bad for the heat pump?
No — it doesn't run the heat pump at all. It's bad for your bill.
Is emergency heat the same as auxiliary heat?
Same strips, different rule. AUX = automatic backup alongside the heat pump. EM HEAT = manual, strips only.
Why does my thermostat say "AUX heat" all the time?
Below 40°F, during defrost, or after a big setpoint jump it's normal. All the time on a 55°F Orlando day means the heat pump isn't doing its share — book a diagnostic.
How much more does emergency heat cost?
Roughly 2–3× per hour — about $1.50 vs $0.50–$0.75 for a 3-ton heat pump, at typical Orlando electric rates.
Should I use emergency heat when it's really cold?
No. In Orlando "really cold" is 30–35°F and the heat pump still works; AUX will engage on its own.
Does a gas furnace have emergency heat?
No. EM HEAT only exists on heat pump thermostats.
What does it cost to fix stuck-on heat strips?
$89 diagnostic; sequencer or relay $150–$350; heat kit $350–$700 if the elements are damaged. Full table: heating repair cost.
Bill Spiked? $89 Finds Out Why — Credited to the Repair.
5.0 stars, 120 Google reviews. Video-documented diagnostics. 90-minute arrival or $200 off. Same price 24/7.
Call (407) 465-7777Smart Home Air & Heat — 10226 Curry Ford Rd, Orlando, FL 32825 — [email protected]