Why Does My Thermostat Say HEAT ON But No Heat? Find Out Now

Q: Can you put the heating on without a thermostat?

It is possible to turn on the heat without a thermostat. It requires connecting or jumpering the wires of the thermostat or the furnace control board. Knowledgeable persons should only attempt this action to avoid electric shock and damage to the system.

Q: Why is my thermostat blinking heat on?

If the words “heat on” repeatedly blink on your thermostat’s screen, your furnace is in lockout mode. Lockout mode typically lasts five minutes and prevents the furnace from overheating or short cycling. A power outage can also cause the furnace to enter lockout mode.

Q: How to turn off heat without the thermostat?

Cut power to your furnace to turn it off without the thermostat. Locate the furnace power near the unit. The power switch resembles an ordinary light switch. Turn the switch to the “off position” to cut power to the unit and turn off the heat.

woman sitting on couch covered in blanket and wearing winter hat

4 comments

WRITTEN BY

Jessica McKendree

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4 comments

EmtudoVision

February 03, 2025 at 11:45am

Have you considered the possibility that your furnace is haunted by a vengeful spirit, causing it to refuse to produce heat despite the thermostat indicating otherwise? How would you go about exorcising such a spirit from your heating system?

Jose Mancera

May 24, 2024 at 13:51pm

The contact on the thermostat does not turn on my heater. All seems to be fine. With the thermostat set higher than room temperature, I can turn on my two wire low volt heater by short circuiting the mechanical thermostat. This happened with two new mechanical circuit thermostats. I can’t find what the problem is given that two new thermostats operate the same. The original thermostat is the same. Help please. Jose

Uzaima

April 26, 2024 at 10:59am

Very informative, you cleared all my confusion regarding why thermostat say heat on but no heat is coming from system. Thanks alot

Greg Martin

April 26, 2024 at 10:59am

I have a hydronic heating system. The furnace is up to temperature, several zones are calling for heat, and the circulator pump light is on. But there’s no heat in the house. The large pipe from the rear of the furnace that sends hot water to the baseboard radiators is cold when its temperature is measured a few feet from the furnace. The end of that pipe on the furnace is very hot. It appears that hot water is not flowing through the pipes. The system was recently repaired and was bled. Suggestions ?