Short answer: emergency heat (EM Heat) shuts off your heat pump's outdoor unit and heats your home with electric resistance strips only. Use it only when the outdoor unit is broken or damaged, and call for service. Running on emergency heat for days can make your electric bill climb sharply, because resistance heat uses far more electricity than a working heat pump.
Heat pumps are common across Alcoa and Blount County because they heat and cool efficiently in our climate. But the emergency heat setting on the thermostat confuses a lot of homeowners, especially on the first cold mornings of the season.
What is the difference between auxiliary heat and emergency heat?
- Auxiliary heat (AUX) turns on automatically. The thermostat adds electric heat strips alongside the heat pump when it needs a boost, such as on very cold mornings or during a defrost cycle. Seeing AUX on now and then is normal.
- Emergency heat (EM) is a manual setting. You switch it on yourself, and it turns the heat pump off completely so only the strips run.
If you see AUX running almost constantly, even in mild weather, the heat pump may not be carrying its share of the load and should be checked.
When should I use emergency heat?
Switch to emergency heat only if:
- The outdoor unit is not running at all
- The outdoor unit is damaged, iced solid or making grinding or banging noises
- A technician has told you to use it until a repair is made
Then schedule emergency HVAC service in Alcoa. Emergency heat is a bridge to a repair, not a way to heat your home through the winter.
Why does emergency heat cost so much more?
A working heat pump moves heat from outdoor air into your home, which lets it deliver more heat energy than the electricity it uses. Electric resistance strips cannot do that. They turn electricity directly into heat, so the same amount of warmth costs more to produce. The exact difference depends on your system and the weather, but homeowners who leave EM Heat on for a few weeks often notice it on their next bill.
Should I switch to emergency heat when it gets really cold?
Usually not. Modern heat pumps are designed to keep working on cold East Tennessee nights, and your thermostat will bring on auxiliary heat automatically when it is needed. Switching to EM Heat just because it is cold outside takes your most efficient heat source offline.
The exception is a system with a known problem. If the house cannot stay warm and the outdoor unit is struggling, use EM Heat to stay comfortable and call for service.
Signs your heat pump needs repair, not emergency heat
- The outdoor unit stays covered in thick ice and never defrosts
- The outdoor fan is not spinning while the compressor hums
- AUX heat runs constantly even on mild days
- The air from the vents stays cool for long periods
- The breaker for the outdoor unit keeps tripping
- Your electric bill jumped without a change in how you use the system
These usually point to a refrigerant issue, defrost control failure, bad capacitor, fan motor or reversing valve problem. All of them need a trained technician.
Related: HVAC repair in Alcoa, why a heat pump runs constantly and maintenance and tune-ups.
How to keep your heat pump off emergency heat this winter
- Change the filter regularly. Restricted airflow is a top cause of heat pump problems.
- Keep 2 feet of clearance around the outdoor unit and clear leaves and snow.
- Avoid big thermostat swings. Raising the temperature several degrees at once can trigger expensive auxiliary heat.
- Schedule a fall tune-up so defrost controls, refrigerant performance and backup heat are tested before the cold sets in.
A Comfort Plan keeps seasonal maintenance on the calendar so you do not have to remember it.
Emergency Heat FAQs for Alcoa Homeowners
Is it bad to run emergency heat?
It will not hurt the system, but it costs more to run. Use it only until your heat pump is repaired.
Why does my thermostat say AUX heat?
Your thermostat is adding electric heat strips to help the heat pump. Occasional AUX is normal. Constant AUX is a sign the heat pump needs service.
Can I damage my heat pump by not using emergency heat?
If the outdoor unit is clearly broken, keep it off and use EM Heat to avoid more damage. Otherwise, let the system run normally.
Who services heat pumps in Alcoa?
True Comfort Heat & Air is a veteran-owned HVAC company based in Alcoa, TN License #81229, servicing all major heat pump brands across Blount County.
Heat pump stuck on emergency heat?
Request heat pump service or call (865) 336-0176. We will find out why the heat pump is not carrying the load and get you back to efficient heat.
