"Greg O" writes:

"Peter Wells" wrote in message
...
I've a motor/fan assembly from an old air handler ( off a 3 1/2 ton AC,
ballpark 300 cfm), it was working when it came out. The plan is to make
an air cleaner to reduce dust in the workshop by putting hte fan in a box
with a filter on the intake. When running as an air handler it took a 20
* 20 in filter; I'll stick with the same. Am I wasting my time, any tips
before I start?


3-1/2 tons comes out to 1400 CFM, but yes it will work fine for a air
cleaner. I did the same using an old furnace blower. I use two 20"x20"x2"
standard pleated paper filters back to back. When the outer one gets packed
I toss it, move the inner one out and stuff a new one in the inner position.
My nose used to get full of crap after wood working or metal working in the
garage, but not any more.
Pretty soon someone will come along and tell you it is a waste of time, but
don't believe him!


I'm another person with a shop-made air cleaner, using a blower
salvaged from an old furnace. Don't know the cfm of the blower, but it
does a pretty good job hanging from the ceiling of my 20'x25' shop.

I installed the blower at one end of a box, put a large pleated fine
furnace filter in the middle, mounted on an angle to reduce vertical
height of the box, and then used a couple of coarse washable fibreglass
filters at the far (intake) end. The blower sucks air through the filters.
Part of one side of the box is removable to get access to the filters. I
wash the coarse ones periodically, but the fine one gets replaced when it
gets clogged.

The blower is a two-speed unit, so the box has two switches: a normal
on-off switch, and a three-way switch that changes the blower speed. I
normally leave it running on low most of the time I'm working, and then
turn it to high if I'm doing major dust production with tools that don't
hook up to the dust collection system (e.g. sanding). On high, it moves a
lot of air and clears things up in a hurry.