Furnace continues to blow air after heated home

Steve Garson_2

Constant circulation also is important in school buildings simply to provide ventilation and necessary air changes.

Joy_2

Furnace continues to blow cool air after heating home

My furnace's motor keeps running after heating the home. Any thoughts on what can be adjusted to fix this.
Thank you for your help.

Eugene Silberstein 3

Two Reasons

Blower operation at the end of the heating cycle is normal. This extended blower operation allows the heat exchanger to cool down which will help prevent it from cracking. There is a delay built in to the control circuitry that will either turn the blower off after a predetermined time interval or after the heat exchanger has cooled to a predetermined temperature.

If, however, the blower fails to turn off at all (after 3 minutes or so) you need to check the fan switch on your thermostat. The fan switch has two settings: AUTO and ON. If the fan switch is in the ON position, the blower will remain in operation all the time. If such is the case, move the selector switch to the auto position and your problem should be resolved.

If this does not take care of your situation, you may have a defective fan relay or other component and here is your solution for that. On the left side of your computer screen is a link to "Find a Professional". Click on that link and locate someone in your area that will be able to evaluate (and repair) the system for you.

Hope this helps and have a great winter.



Number One:

Timco

Could very well be the fan limit control, or fan control...some call it either. It has a dial in the middle that rotates with the temperature in the firebox. As the firebox gets to temp, the fan starts up so as to only blow hot air. As the thermostat is satisfied, the gas valve shuts off, and as the blower keeps blowing, it cools the firebox and when the temp is low enough, this switch releases the fan. The part is about 70-100$. Rectangle shaped cover, in behind the upper access door. High voltage side, for the fan power, and a low voltage side, as a temp limit on the gas valve.

T

David DeBord

Blower keeps running

Is this an electric furnace? If it is then it could be a "stuck sequencer".

Dave Faust

Constant Air Circulation

On the campus where I work several buildings have terminal units that blow 24/7/365. The air is just warm enough to keep the building comfortable. (This really confounds students who are used to their parents high temp. sorched air systems). Isn't C.A.C. (constant air circulation) supposed to be the "Cadillac" of forced air comfort? I realize not everyone would think this is a value worth paying for.

Joy_2

Blower keeps going

Thanks to all. I took the advice and called a Professional.

Weezbo

find a grey 5X2\"X2 1/2\" box,take the retaining screw loose,

inside is a deal called a fan limit switch. it has a dial on it likely set 150 200 with a 50 degree temp span. push it in and turn it aas far as it will go to the right ...twice...then turn it all the way to the right and let it spin back.....dont put your fingers on the wires or the screws holding them down..it doesnt feel too swooft. that generally clears the dust off of them enough that it will hang in there long enough for someone to stop by and fix it.