Attic fan broke down: several questions

ilyaz · 06-19-2009, 10:25 AM

I have a 10-yr-old attic exhaust fan that recently broke down. I am not sure what's wrong. When I turn on the switch, sometimes I get humming coming from the motor (I think) and sometimes I do not. At one moment when I was looking at it and was not doing anything in particular, the humming suddenly started, the fan did maybe a 1/2 circle rotation then it stopped and a few seconds later the humming stopped as well.

A couple of months ago we had some insulation work done in the attic. The contractor installed special soft screens that cover the entire attic area and are supposed to prevent our upper level rooms from getting hot in the summer. Is it possible that these screens somehow restricted air flow forcing the fan to work harder? Also, one thing that I noticed when I sat in the attic is that there is an "outgoing" window in front of the fan where the hot air gets pushed out. But are we also supposed to have an "incoming" window on the opposite wall? If not, then is the airflow restricted too much by the new barriers? Finally, what do you think is wrong with the fan and is it worth repairing or do we need to replace it?

Thanks much!

handyguys · 06-19-2009, 12:50 PM

My guess would be that the attic fan's motor is shot. Some motors are sealed, some have a lubrication port. My guess is if it has the lube port it hasn't been maintained. Regardless its likely a goner.

if the motor is separate and uses a belt to drive the fan you may be able to replace just the motor. My guess is the cost of a replacement motor would be similar to a whole new fan. Same with a motor repair.

As for 'makeup air' - yes, you should have makup air. This can be in the soffits, the ridge or in an opposite gable vent.

Look first at the soffits, from the outside. If you see vents go in your attic and make sure they are not blocked or covered by your insulation. If they are get your insulation contractor back to re-do his incorrect installation.

If you have no soffit vents, no gable vent and no ridge vent - you need to add something. Gable vents, if you have a place for them, are easy enough to install. Ridge vents are easy too if your roof is not too steep.

Good luck.