Why heat may not restart
After an outage, many heating systems need a few minutes to reset, some lock out after repeated power flickers, and a surge can damage control boards or blow a low-voltage fuse.
Heat pumps are often designed to wait before restarting the compressor. In freezing weather, some models need time with power restored before they run normally.
Safe restart sequence
- Wait until power has been stable for several minutes.
- Set the thermostat to OFF.
- Check the breakers for the furnace or air handler and the outdoor unit.
- Turn the furnace switch off for 30 seconds, then on.
- Set the thermostat back to HEAT and wait up to 10 minutes.
- If nothing starts, note any error-code blinks and call.
Post-outage problems
| Symptom | Likely cause |
|---|---|
| Thermostat blank | Tripped breaker or blown 3–5A fuse on the furnace board |
| Furnace dead, breaker fine | Surge-damaged control board or transformer |
| Heat pump outdoor unit silent | Compressor time delay, tripped outdoor breaker |
| Inducer runs, no ignition | Lockout after repeated flickers; power cycle once |
| Blower runs nonstop | Board stuck, or high-limit tripped |
Generator safety
Run portable generators outdoors only, at least 20 feet from windows, doors and vents, and never in a garage. Connecting a generator to a furnace or home wiring requires a transfer switch or interlock installed by a licensed electrician. Backfeeding through an outlet can kill utility line workers.
Ice storms and long outages
Ice storms can cut power for days. Gas furnaces need electricity to run, so they go down with the grid too.
If an outage will last into a hard freeze, protect pipes, see frozen pipe steps, and consider a warming center or a stay with friends.
Protect equipment from the next outage
- Whole-home surge protector at the panel
- Dedicated surge protector for the HVAC system
- Transfer switch for generator readiness
- Wi-Fi thermostat alerts for low indoor temperature
Outage FAQs
Will my gas furnace work without power?
Almost all modern gas furnaces need electricity for the ignitor, inducer, controls and blower. Some older gravity furnaces and standing-pilot heaters don't.
Can a power surge ruin a furnace?
It can damage the control board, transformer or ECM blower motor. The rest of the furnace is usually fine.
Next steps
Ready to get it fixed? Call (888) 555-0143 to reach a licensed provider in your area. Related guides:
Busy winter markets: emergency HVAC repair in Texas · emergency HVAC repair in North Dakota · emergency HVAC repair in Minnesota · emergency HVAC repair in New York · emergency HVAC repair in Massachusetts · emergency HVAC repair in Tennessee · all states.