heat turns on and off repeatedly

[Freon]

If you turn your thermostat 10 degrees past room temperature thereby calling for heat, does this cycling happen? When the burners turn off does the furnace main blower still keep circulating air in the house or does the blower turn off also?

What make model it the thermostat?

Check that your filter is clean and that ALL supply registers (air out) and ALL return registers are open and not blocked. Usually low airflow from a dirty filter will cause the heat exchanger to overheat and that can cause the burner to short-cycle HOWEVER the blower will remain on. That's why I asked the first questions


Tell us the make/model of the furnace. Has any work been done on the furnace or house recently? Any recent electrical storms/power company problems?

[Freon]

Go to the furnace and see if there is a small metal (usually aluminum) box on the front just above/next to the heat exchanger. If there is, you should be able to remove the cover by squeezing the sides and pulling it back toward you. Inside you will see a dial. This is the blower control. Let me know if you have this type of control.

[Freon]

What is the make and model of the furnace control board? Double check the furnace setup in the thermostat settings. Your blower seems possessed by a poltergeist usually from a flaky control board.

[Freon]

The User Manual for the thermostat will tell you how to set it up. If you lost the manual, Google the make/model of the thermostat and you will find the manual online.

[Freon]

After the temperature in the room reaches the set temperature at the thermostat the burners go off and the main blower (fan) is supposed to run to get the heat remaining in the heat exchanger into the house. So that all seems normal.

The unique part is the main blower starting again. In some fan control units, the blower would be powered if the heat exchanger was too warm. But since you do not appear to have that type of fan control I am a bit baffled. I would not worry about it as long as you're getting the heat called for by the thermostat. Otherwise you need to call someone to test the control board.

[Freon]

To quote you after I asked this question, "I do not beliieve it has that.....Ive been under the house and seen it a million times and I dont recall ever seeing a box with a dial inside."

Go re-read my posts and it tells you what to look for.