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?

TIA

Peter

That fan is more likely a 1200-1400 cfm fan if it came off a 3 1/2 ton
system. It should make a pretty good air filter for a workshop, but locate
it where the output won't blow in your direction or working may feel a bit
uncomfortable. Your design needs to make provision for several filters, a
mesh pre-filter followed by one or two of the newer paper sub micron type
filters

--
Charley

"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?

TIA

Peter

"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?

TIA

Peter


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!
Greg

Air cleaner, downdraft sanding table, outfeed table/cart

http://web.hypersurf.com/~charlie2/A...irCleaner.html

diesel truck or pool/spa filters to catch the really fine stuff
- the little ones that get WAY down in your lungs.

charlie b

"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.

Thanks to all who replied, a lot of good advice; I'm going to search around
for some cheap filters and get after it.

Peter

"charlie b" wrote in message
...
Air cleaner, downdraft sanding table, outfeed table/cart

http://web.hypersurf.com/~charlie2/A...irCleaner.html

diesel truck or pool/spa filters to catch the really fine stuff
- the little ones that get WAY down in your lungs.

charlie b

"Peter Wells" wrote in message
...
Thanks to all who replied, a lot of good advice; I'm going to search
around for some cheap filters and get after it.

Peter


Don't search too hard, any 2" pleated paper filter you can find at Menards
should do.
Greg

Thanks to all who replied, a lot of good advice; I'm going to search
around for some cheap filters and get after it.

PeterDon't search too hard, any 2" pleated paper filter you can find at Menards
should do.
Greg

I made something similar - basically a sealed box with a 320cfm
squirrel-cage blower. I was going to give the opposite advice - find
some NICE filters (even the super-micro-ultra-allergen are maybe
$20?). Protect your lungs! This is still a LOT cheaper than any of
the commercial air cleaners, and I've found the nice filters last a
long time when you get some cheap electrostatic filter as a pre-
filter, and that can even be vacuumed off a couple times to extend its
life slightly.
To answer your original question, from my experience, with the double-
filter setup as described above, a home-made air cleaner will
definitely reduce the amount of airborne dust in your shop. (Notes:
my shop is very small - maybe 800 cu ft., I still wear a respirator
when sanding or doing anything dusty, and I SUSPECT that placement of
the unit and direction of exhaust and shape of the room have a lot to
do with overall efficiency.)
Good luck,
Andy

"Greg O" writes:


"Peter Wells" wrote in message
.. .
Thanks to all who replied, a lot of good advice; I'm going to search
around for some cheap filters and get after it.

Peter


Don't search too hard, any 2" pleated paper filter you can find at Menards
should do.
Greg

I'd agree. My air cleaner has a standard pleated furnace filter for
the fine collection, and a [cut with a utility knife] standard washable
fibreglass furnace filter for the coarse filtration. About $5 for the
fancy one; $2-3 ea. for the coarse ones.

The design process was:

- decide how big a box I needed to hold the furnace blower, and how to
mount the blower so that its output was all directed outside the box and
it could suck air from the other end of the box. (It's bolted to one end,
with a standard HVAC grill covering the hole.) I made the box using pieces
of broken wooden hockey sticks for framing and MDF (probably 3/8") to form
the sides, top, bottom, etc. You could probably use cheap plywood and skip
a frame. I used scraps I had on hand.
- decide how to mount the largest common fine filter size I could fit
in that box, so that the fan had to suck air through it.
- leave the other end open, with enough bits of wood glued on to form a
slot I can stick the coarse filter in.
- find a spot to mount an electrical box for the switches. I used one
of those plastic boxes with the foam covers that are supposed to seal
against vapour loss on exterior wall, so that dust wouldn't get into the
box from inside the air cleaner. (The electrical box is mounted inside the
air cleaner. You could moutn it outside to avoid all that.) I used an
extension cord with the end cut off to give me my wiring to plug into the
wall.

That's about it. Crude, quick, easy, and after about 10 years I've had
no urge to change it.