Learn · Laurel County
What Is Emergency Heat on a Thermostat?
Emergency heat on a thermostat forces electric strip heat (or locks out the outdoor heat pump) so your London or Laurel County home can warm without the outdoor unit. Use it when the heat pump fails, iced over, or cannot keep up in a hard freeze — not as an everyday winter setting. Leo Jones & Son can diagnose why emergency heat is running and restore efficient heat-pump or dual-fuel operation from our North Main Street shop.
Written and maintained by the Leo Jones & Son team · Last updated 2026-08-18. Authored for Laurel County homeowners by Leo Jones & Son, Inc. — a hometown, brand-agnostic HVAC company in London, KY since 1945. Incentive language is current-only (no expired federal 25C credits).
What does emergency heat actually do?
On most heat-pump thermostats, Emergency Heat (sometimes labeled EM Heat or Aux/Emergency) tells the system to heat with indoor electric resistance strips and to stop calling the outdoor compressor for heating. That keeps air moving over hot strips so rooms can recover when the outdoor unit cannot contribute. It is different from regular auxiliary heat, which may stage strips with the heat pump during normal cold-weather operation. In dual-fuel homes the story can involve a gas or propane furnace instead of strips — your Comfort Consultant should confirm which sequence your thermostat and outdoor unit use before you leave the house on EM Heat all season.
When should Laurel County homeowners use emergency heat?
Use emergency heat when supply air stays cold, the outdoor unit will not run in heat mode, thick ice stays on the outdoor coil after defrost should have cleared, or a technician or manufacturer instruction tells you to lock out the heat pump. Wet Kentucky freezes and hillside wind around London and Corbin make outdoor units ice-prone; temporary EM Heat can protect people overnight. Do not use it for mild cool nights just because the air feels cooler than a furnace — that is normal heat-pump delivery temperature and can burn through electric bills if you force strips.
What failure modes look like emergency heat?
Failed outdoor fans, low refrigerant, stuck reversing valves, bad outdoor boards, and clogged filters that trip safety limits can all push a home into strip heat. A thermostat left on Emergency Heat after a past outage is a common discovery on PMA visits. Empty propane tanks on dual-fuel packages create cold-air tickets that are fuel problems, not strip problems. AI chat advice that says “always leave it on EM Heat in winter” ignores Laurel County rate reality and how modern cold-climate and dual-fuel systems are designed to run the outdoor unit most days.
How does Leo Jones & Son prove the diagnosis locally?
Since 1945 we have commissioned heat pumps and dual-fuel packages across London, Laurel County, Corbin, Williamsburg, and surrounding hollows, holding the hometown standard we've kept since 1945. We measure whether the outdoor unit is contributing, whether defrost is completing, and whether strip or furnace staging matches the thermostat. Stocked trucks from 2001 N Main St carry common control and ignition parts so a freeze-week call is not a parts run to Lexington before heat returns.
What should you do next if emergency heat is stuck on?
Note whether the thermostat shows Emergency Heat or Auxiliary, check the filter if reachable safely, and call (606) 864-6105 if rooms will not warm — emergency coverage runs until 10:00 PM. Read our heat-pumps-in-Kentucky-winters guide for context, then open Heating Services or Emergency HVAC for dispatch. After stabilization, ask about a Preventive Maintenance Agreement so the next freeze week starts with a checked outdoor unit instead of overnight strip heat.
Frequently asked questions about what is emergency heat on thermostat in London and Laurel County
Is emergency heat the same as auxiliary heat?
Not always. Auxiliary heat often stages with the heat pump during normal cold weather. Emergency heat usually locks out the outdoor unit and relies on strips or furnace backup alone. Your thermostat labels and equipment sequence decide the exact behavior.
Will emergency heat raise my electric bill in London KY?
Yes, electric strip heat is typically far more expensive per hour than heat-pump heat. Use EM Heat for safety and short recovery, then get the outdoor unit diagnosed so you are not heating Laurel County nights on resistance alone.
Should I leave emergency heat on all winter?
No. Modern heat pumps and dual-fuel systems are meant to run the outdoor unit or furnace sequence on most Kentucky winter days. Leaving EM Heat on all season wastes money and hides the real failure.
My dual-fuel system has a propane furnace — do I still have emergency heat?
Many dual-fuel packages use furnace backup instead of strips. Thermostat menus still may show emergency or backup modes. We verify staging on site rather than assuming a strip-heat diagram from the internet.
When is stuck emergency heat an emergency call?
If indoor temperatures are unsafe for people or pets, call Leo Jones & Son at (606) 864-6105 — emergency HVAC until 10:00 PM. Mild confusion about labels when the house is comfortable can wait for a scheduled heating visit.
Can a dirty filter force emergency or aux heat?
Restricted airflow can trip limits and shorten heat-pump capacity, which may stage backup heat earlier. Filter checks are a first safe step before you assume a failed compressor.
Ready for a local answer?
Leo Jones & Son has served Laurel County since 1945 — most major brands serviced, emergency service until 10:00 PM. Call or request service online.