Oversized fan /w Variac

Hey hey. I'm currently running a 4" active air 167 cfm fan /w 150 cfm rated phresh filter but it is still getting a little bit warm (high 80s.) Today we are putting a hole into the attic (my house so it's OK) and will be hooking it up to vent outside.

Here is my question: Will it be OK to run a 8" 950 cfm with the variac dialed way down to make the noise even lower?

The filter is less than a year old and I was hoping to run with it for a bit longer. When it comes time to replace it I will get a higher rated one.
I place the filter inside the room.

You can't really turn it way down, the motors don't perform well and start to surge-slow-surge-slow just enough to make the noise so much more annoying.

So what would be safe to run it at on a continuous basis? 75%, 50%, 25%?

bellcore said:

So what would be safe to run it at on a continuous basis? 75%, 50%, 25%?

Click to expand...

I would just use your ears and find the setting that way. Once you go too low you will notice the sound is less consistent and more alternating. Stop before you hear significant alternating as that is what will kill the motor.