I've a fan/motor assembly out of a house central air/heat air handler, it
probably moves around 300 cfm. I'm planning on putting it in a box with a
std filter (it used a 20 * 20 inch) on the inlet. Will I notice an
improvement in the airborne dust in my shop (30 * 20 ft)? Any tips?

TIA

Peter

Peter, if you want the best filtration with the maximum flow, you may
want to check our an HVAC supply company and get a 'bag' filter. These
are the ones that are 6" to 12" (or more) deep. The pockets vastly
increase the surface area, enabling you to move more air. To do it
right, you would also add one of the standard fibre filters (not the
pleated ones) in front of the bag filter to trap larger particles.

May be more money, but it will last longer and trap more dust.

Michel
www.woodstoneproductions.com



On Jan 27, 6:35 pm, "Peter Wells" wrote:
I've a fan/motor assembly out of a house central air/heat air handler, it
probably moves around 300 cfm. I'm planning on putting it in a box with a
std filter (it used a 20 * 20 inch) on the inlet. Will I notice an
improvement in the airborne dust in my shop (30 * 20 ft)? Any tips?

TIA

Peter

Peter Wells wrote:
I've a fan/motor assembly out of a house central air/heat air handler, it
probably moves around 300 cfm. I'm planning on putting it in a box with a
std filter (it used a 20 * 20 inch) on the inlet. Will I notice an
improvement in the airborne dust in my shop (30 * 20 ft)? Any tips?

TIA

Peter

I made my shop air cleaner out of a 'donated' furnace blower & motor. To
this I added a scrap plywood box sized to serve as a tall workbench
(grinder, belt sanders and bench-top arbor press) with 2 - 20"x20"
filters taped edge to edge to make a single layer of filter media. These
were then taped to two more layers (making a 6 filter stack, 3 high, 2
wide) using a standard coarse furnace filter on the outer panel, a
medium (~5 microns) middle layer and a fine (~0.3 microns) inner panel.
The bench gets its air intake from both sides, each of which has a stack
like this, making some 800 sq. in. of filter face. The inner filters are
pleated so there is quite a bit more filter surface than is at first
evident ... I'd guess about 3x. The coarse filters are that woven
fiberglass stuff meant to keep small birds and large bugs out of the
furnace. I spray them lightly with adhesive when I first install them so
they'll build a bit of a cake faster.

I do not secure the filters in place, they are held against a cleat by
suction. This gives me an audible clue (by how loud they slap the cleat)
to their level of dirtiness. The dirtier they get, the louder they are.

With fresh filters, there is an obvious, but not (to me) uncomfortable
flow of air in the shop.

My shop is about 2,700 cu ft, so I estimate that my air is getting
filtered roughly 30 times an hour.

I don't count on my (so-called) dust collector for much ... it emits ~30
micron dust and sits downstream in the air flow from where I am working
when it is operating.

The air coming out of the whole-shop filter is good enough to place a
freshly varnished piece in its output flow and go on back to work.

Sure beats a box fan with a furnace filter! (Which sure beat nothing at
all.)

Bill

PS, keep wearing that respirator ... you are closer to the source of
dust than the filter is, so you get first dibs on it. When possible,
work with your back to the filter ... let it blow the dust away from you.

--
I am disillusioned enough to know that no man's opinion on any subject
is worth a **** unless backed up with enough genuine information to make
him really know what he's talking about.

H. P. Lovecraft


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