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Arrived back in Canada 2 weeks ago and we've already found a house to put an offer in. My wife claims our search was for a workshop with a house attached -- a bit of an exaggeration, I'd say. The candidate has a 30 x 16' room on the lowest level adjacent to the garage with a south-facing glass slider at one end. I'm pleased, but already thinking about shop set up and greatly improving my dust control over what I've accepted in the past.

Several interesting threads on OLF have dealt with ceiling-mounted air filtration units. Several brands with rather subtle differences (I suspect many/most come out of same plant in Asia). A good article on placement and sizing also found here: https://www.canadianwoodworking.com/tools/ambient-air-cleaners. That article recommends placement of the unit with the intake about 1/3 along the longer wall, and about a foot from the wall -- all this to encourage air circulation around the room. Got me wondering if indeed two smaller units mounted on either side of the shop wouldn't be a significant improvement over a single large unit -- more filter area? even better circulation? Quieter operation?

Anyone here have experience with using two of these in their workspace? Any engineers who can offer insight?

Fingers crossed we're successful in having our offer accepted on the house!

My two cents is that an electric fan in another part of the shop will circulate the air fine.

I would be worried that they would work against each other by making the air swirl around, and create some dead spots that wouldn't get filtered. Of course, I just might be absolutely wrong, and that it would be a great idea!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Might I suggest that if you are really interested, you might look up Mario Proulx's air cleaning system that he devised in his shop. Essentially it uses the closed in space between joists in the wall and a used furnace fan in a box at the floor. Collects at the floor level (dust settles) using high efficiency filters, and exhausts near the ceiling level. Helps with air circulation and all. Furnace fans move a lot of air. Could be set up to use two sections of wall to move more air. Simple and if you can find a used fan, pretty inexpensive.

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Waddy

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I'm not sure what those things are supposed to do for your lungs if they don't have something like a HEPA filter. I guess they would clear the big chunks out of the air, but all of the really bad small stuff just gets blown around even more.

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Pat

What Pat said.

It's the sub micron stuff that kills ya. That being said, you can get sub micron filters that retrofit nearly everything from Wynn Environmental.

A while back I was having trouble in my shop. The second I walked in I'd get the flu like symptoms. So I added a Honeywell HEPA filter and now my shop is fine and dandy. One day I'll spring the 75$ to turn my air filter into a HEPA too.

Anyway, I have no data to back up my claim, but it seems to me that the more air you have passing through more filters would be a good thing.

I have two ceiling mounted air filtration systems in my shop but only because my shop is L shaped and one unit wouldn't effectively clear all the dust. I have two smaller Jets that have been discontinued. These units, like most, use a two filter system. The outer filter allows more air to pass through and filters 98% of 5 micron particles and the inner filter gets 85% of the fine 1 micron particles.

Since the inner filters are hard to find and expensive, I decided to make the unit a one filter system. I remove and leave out the inner filter and replace the outer filter with a finer, higher rated filter. I use MERV 13 filters that I have custom made at filtersfast.com. This is about what the rating of the inner filter. I always crank up the unit to the highest setting so to get the most suction. The higher rated the filter, the finer the fabric and the less air is able to pass through.

To complement the two air filtration systems, I have a Hunter air purifier that sits on the ground of my shop. Oh, I also have a dust collection system, but nothing fancy, just a 2hp bag dust collector that I replaced the bag with a Wynn canister filter. People are always surprised with how dust free my shop is.

Tim, I was a bit off topic. Back to your original post...the two filters and tactical mounting locations seem like an excellent idea. However, two is probably overkill for a small shop. These air filtration system really do a great job at clearing the air.

I'd focus on getting the dust collection at the source. I've had two units in my shop and found that they do practically nothing except rattle my brain. You really need to get it at the source with a good dust collection system. Additionally, a downdraft sanding table with high walls around three sides to control the dust will be very helpful.