Attic Fan Issues

Just installed a new Master Flow attic fan. 30". All went well and seemed to work well most the day today. After about 8 hours of use I noticed that the louvers were not open all the way and the fan was set on low, so I set it to high and it didn't change the speed of the fan it just starting making this loud humming noise consistently when on high.

Any suggestions before I take this thing down or hire someone to look at it. Now the only things I can think of but not sure if it would contribute to what the fan is doing. 1. Not sure I have enough attic ventilation. 2. When tightening the belt, the suggested tightness seemed very, very loose so I tightened it just a little but not much. Not sure if this helps. Thank you for any help

 

I'm assuming this is a fan that exhausts attic air to the outside.

The two issues you mention are both possible causes, insufficient air flow due to limited ventilation and/or belt tension.

If you open your attic access while the fan is running it will be able to draw air from the house and if it speeds up and sounds normal then it is an air source issue.

If not, then check to see if the fan spins freely with the power off.

Bud

 

Another thing to check is the exhaust shutter (louvers). Make certain the louvers move freely and don't stick.