Shop-made air cleaner?

[jethro]

I got an old furnace blower for free, and I'm trying to find out if it will work for a homemade air cleaner. All I know of the specs is:

quote:Belt driven, squirrel-cage blower in working order. Casing is 12" wide and 18" diameter. Motor is 3/4 hp, 120 V., 1725 rpm.

Is this too big/powerful for an air cleaner in a 400-sf shop/garage? Any tips or tricks for building such a beast?

Thanks!

[sharshan]

I ended up getting an older furnace blower about the same hp. It took me a bit to come up with the design, and then I made it smaller due to the fact it just looked too darn big in my shop (1 car garage). I used BC plywood, an AC vent from HD, an electrostatic filter with another filter behind it just for efficiency. It works pretty good, and I hung it on chains from the ceiling.

I attached some pictures for reference. I have no plans for them (did them by the seat of my pants) but it came out to be pretty cheap. I used an extension cord (good grade) and cut it up to wire the blower to it. I have it on a wall switch in the shop.

I made a window for the MARK II model just for kicks (it's nifty to watch the blower go 'round).

Craig.

[JR]

quote:Originally posted by sharshan

I made a window for the MARK II model just for kicks (it's nifty to watch the blower go 'round).

Boys and their toys!!

[dedaddy]

Jethro, at 18" in diameter, that thing is BIG for an air cleaner. The low speed will make it quiet. Design the box to hold the biggest filter you can find at HD or Lowe's to keep the face velocity low. Or maybe two smaller ones. I would get the HEPA filters, too. My air filter has a 10" blower and moves about 1400 CFM through a flat filter in series with a bag filter.

[Turaj]

Jetro

I don't see any problem using this. For a shop your size you need something around 320 CFM (changing the air 6 times per hour). As for plan it is really a box with 2 openings! The only tip(s) that I can offer: 1) find your filters first, I use 3 different filters in mine (first one is a cheapie that gets most of the stuff and I replace it most often; 2) make sure you have access to the blower afterward (don't glue everything).

Hope this helps

[pierhogunn]

just looking at that huge aircleaner had me thinking why not set the filter into the box at an angle, and then flatten the box out like this





would the angle of the filter matter?

would angling the filter like that reduce the ability of the filter to clean?

Dan in Charlotte, NC

[WY]

You're lucky! I had to pay nearly $90 on ebay for one. Called all round where I lived and all the HVAC people just laughed at me and said stuff like that just gets taken to the dump. I have a 1/3hp with 1200 cfm. It works great for me. If I stand close enough I can actually feel a slight suction pulling on my pant leg so I know it's circulating air pretty well. I built one based on the plans from Controlling Dust In The Workshop by Rick Peters. Mines pretty big, and I put it on casters so I can wheel it around. IIRC Peters says something to the point of it makes more sense to have the air cleaner closer to the ground (vs hanging it up) as dust tends to settle to the floor anyway. Not sure which is better or if even makes any difference, hanging or ground level, but I like having mine on casters so I can wheel it to another room if I want to quickly filter/ventilate a room I'm working on (drywalling, sanding, painting, etc.) Btw I use the 20" x20" furnace filters from the borg.

[Woodnut]

You could always go for this one...

I have seen this plan a few times as posts on this forum and have always liked it when I saw it.

Now I guess it's my turn to post it...

[LCHIEN]

quote:Originally posted by pierhogunn

just looking at that huge aircleaner had me thinking why not set the filter into the box at an angle, and then flatten the box out like this





would the angle of the filter matter?

would angling the filter like that reduce the ability of the filter to clean?

Dan in Charlotte, NC

Makes sense to me.
I think the air flow resistance will be a little higher over the squared up box since the duct cross section area is smaller, but not too bad since its short and yo probably have lots of suction with the fan to spare. Might be a little noiser due to higher air velocity and turbulence and, maybe you'll have some problems with the filter bending - might need some wire support behind it.

Two stage filter?

[WEG]

Hi Jethro;

I made one that doubles as a sanding table. It's about 25x25 or whatever the filter size is, and stands on wheels. It's about 3.5 feet high or so. I also used three filters, course one on top, two finer after the blower. This unit pulls air from the top and exits the bottom. Base is off the floor about 4 inches or so. The top is pegboard that I drilled out to make the holes about 1/2 inch. The blower is three speed and I'm running it on "slow". I got the blower from my local fuel oil/furnace guy. I don't know the hp or cfm rating, but it's a direct drive, not belt driven, squirrel cage fan. He says he gets them all the time. Hope this helps out.

I would try to post a pic but after all the heat I took with my "Horizontal Router Slot Mortiser"...whew! (kidding guys )
WEG

[pierhogunn]

jethro, what are the largest outside dimensions of your blower, including the motor and belt?

Dan

[pierhogunn]

I think the key here is filter surface area, I just figured, the hypotenuse of a triangle is marginally longer than either of the sides, so just make the box a rhomboid shape, and viola, your working end would be the hypotenuse of a really nice right triangle,


Dan in Charlotte

[JimD]

I made an air filter out of an old box fan and an electrostatic furnace filter. I'm sure the $200 ones are better but all I payed for is the filter and it works pretty well.

Jim