Furnace kicks on when tempover set temp
- Thread starter Reit38
- Start date
moab11
Well-known member
is it blowing heat? or just running the fan to circulate the air in the house?
fitter30
Well-known member
Gas furnace? Model number of stat?
Older bimetel thermostats had a heat anticipator that was set by either amps by gas valve or burner control. This would shut the gas valve off and blower would run to get all the heat out of the heat exchanger. Rhen the blower would shut down and room temp would be at setpoint. Page 31 anticipator if this is your stat. Under setup. When making a change take baby steps. If it set at 0° try -1° let it run few hours before making another change.
Older bimetel thermostats had a heat anticipator that was set by either amps by gas valve or burner control. This would shut the gas valve off and blower would run to get all the heat out of the heat exchanger. Rhen the blower would shut down and room temp would be at setpoint. Page 31 anticipator if this is your stat. Under setup. When making a change take baby steps. If it set at 0° try -1° let it run few hours before making another change.
This was my first thought.
My second thought was I'm pretty sure mine starts the fan again a few minutes after the initial burn is done, to get the residual heat out.
fitter30
Well-known member
If the fan restarts after the burners are off the fan hasn't run long enought the first time. If the fan control is in a box 21/4" x 3" and a round dial inside "do not turn dial" hold dial there are three settings right one move cw just a little 1/16" try that have to give furnace 5 minutes to see if it comes back onafter it shut downs. That dial is mounted to a bimetel spring. Come back on move it another 1/16".
Sounds like the old Honeywell bimetal coil fan/limit switch.
Like this one?
Honeywell L4064B2236 Combination Fan and Limit Furnace Control - Replacement Household Furnace Fans - Amazon.com
Honeywell L4064B2236 Combination Fan and Limit Furnace Control - Replacement Household Furnace Fans - Amazon.com
www.amazon.com
fitter30
Well-known member
Yes thats the control. That one has a blower on pull and white rodgers made them also.
htmdude57
Well-known member
I agree with fitter30. There are 2 problems. The temperature of the house is overshooting. And the fan kicks on a second time. As he said, go into the thermostat to the anticipator setting and lower the number. That should cut down on the temperature overshoot. But for the extra fan kicking on, the setting I believe you need to adjust is the pointer on the left. See the diagram. Its marked #1 in this diagram. Move the pointer a little to the left, so the fan will run till the internal temp of the furnace is around 75 degrees. Then the furnace shouldn't kick on for the extra run.
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fitter30
Well-known member
Having a fireplace running with a furnace. Fireplace is adding heat to the house getting picked up from the return air one possibility. Thermostat is showing 71 set at 69 when does it come back on? Made any adjustments like post 3.