No Heat
Ecobee Thermostat
Severity: ModerateWhat Does This Error Mean?
Ecobee 'No Heat' is an alert in the Alerts panel meaning the thermostat called for heat, the system ran, but the indoor temperature did not rise within the expected window.
The thermostat is reporting a real symptom — the heating equipment is failing to deliver.
Cause depends on system type: ignition fault on gas furnaces, frozen outdoor unit on heat pumps, blown fuse on electric heat.
Affected Models
- Ecobee Smart Thermostat Premium
- Ecobee Smart Thermostat Enhanced
- Ecobee SmartThermostat with voice control
- Ecobee3 lite
- Ecobee3
Common Causes
- Gas furnace ignition fault — flame sensor dirty or igniter failed
- Heat pump iced over and stuck in defrost
- Electric heat strips fuse blown
- Filter clogged and limit switch tripping
- Pilot light out on older gas furnaces
- Furnace switch (looks like a light switch) accidentally turned off
How to Fix It
-
Check the furnace switch.
Many furnaces have a service switch in the basement or attic that looks just like a light switch — sometimes near the unit, sometimes by the stairs.
If someone turned it off, the furnace cannot run.
This is the embarrassing-but-common first check. -
Replace the air filter.
A blocked filter trips the furnace's high-limit switch and the furnace shuts down for safety.
Replace the filter, then power-cycle the furnace at the breaker to clear any latched limit fault. -
Listen at the furnace.
Stand near the furnace during a heat call.
Inducer fan starting + clicking from the igniter + whoosh = furnace lighting.
Inducer running but no whoosh = ignition failure.
Total silence = no call reaching the furnace, possibly a wiring issue. -
Heat pump: check the outdoor unit for ice.
Walk outside.
If the heat pump is encased in ice, the defrost cycle has failed.
Run the system in Emergency Heat for now (uses backup heat strips), and call an HVAC tech.
Defrost board failures are common after 8-10 years. -
Check breakers and disconnect.
Furnace breaker, outdoor unit breaker, and any disconnect switches should all be on.
Even electric furnaces have multiple breakers — main and per-strip.
One open breaker is enough to drop heating capacity. -
Reset the furnace.
Some furnaces have a small reset button after a lockout — usually red, near the burner area.
Press once.
The furnace attempts another start.
Do not press repeatedly — that can flood the burner with gas. -
Clear the alert.
After repair, open the Ecobee Alerts panel and dismiss No Heat.
The alert stays until acknowledged — the thermostat does not auto-clear it after a successful heat cycle.
Frequently Asked Questions
Will the thermostat keep trying to heat?
Yes — the thermostat continues to call for heat as long as the room is below set point.
If the equipment cannot deliver, the room stays cold and the No Heat alert remains.
Switch to Emergency Heat or Off until the system is repaired.