Coleman 7970-856 question

[Palomino]

Hello,

I have a Coleman 7970-856 in a 1985 Wick manufactured home that is now going on 23 years old but is still running strong and does not breakdown.

Last week the temps were around 93 degress and were extremely humid here in Wisconsin. Dewpoints were around 75--very humid! Anyway, when the temperature in the house reached somewhere around 88 degrees or so the blower fan on the furnace would come on and stay on constantly until nighttime came and the house would cool down and get less humid. It would go off around 85 degrees or so. Is this normal for the furnace fan to run like this? It was just recirculating air thru the vents... The pilot was not igniting the burner or anything it would just blow air thru the vents. This is the first time Ive noticed this in the 3 years Ive owned the place but this is also the first time it's been this warm and humid since I bought the place.

Not sure if this is a problem or not I just wanted to make sure this is normal for this furnace? We do not have A/C hooked up to this furnace.

Thanks,

Mike

[Robert]

Hi Mike,


IF you leave your pilot lit and you do not have a/c and home gets real hot and humid , along with heat from pilot, a fan switch switch will turn on the blower.



That is normal. Not all furnaces do this, but several do.




Thanks,
Robert

[Palomino]

Hi Robert,

Thanks for the reply. May I ask what is the purpose of this function or what is the blower coming on in that situation supposed to do or what benefit does it have?

Thanks,

Mike

[Robert]

Hi Mike,


The fan switch is temp operated and the combined heat from pilot light and home temp can trigger the fan switch closed which turns on the blower.


Put out the pilot light and see if it stops.




Thanks,
Robert