# DIY air cleaner/filter



## Gene Howe

I have a blower from my old furnace that I'd like to use in a box type air filter. Can anybody point me to plans or ideas about building such a unit?

I'd like to incorporate two furnace filters on the inlet side, if possible.

Would I simply build the box to accommodate a normal sized set of filters?

I don't know where to start. All help would be appreciated.

Thanks, folks!


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## Bob Willing

Try this. Do a search on this site for " air filtration".. In the search results go down to the post "air filtration system size". Open this up and scroll down until you see a picture of an overhead filter. I posted this sometime ago with helpful hints. The picture of the one that I made has filters on both sides. It is important to keep the filters 3" away from the blower itself. The size of mine was based on the size of the blower. Mine has a 4 speed motor and I run it on next to the lowest speed. I would do a link but I am not sure how to do it on this site.


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## Bob Willing

Gene
Did you find the post? Did it help? If you need more info let me know?


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## b00kemdano

I often run on the "anything is better than nothing" principle. I made a cube out of some scrap plywood, cut holes in one end and mounted a mess of computer fans that I had lying around. I used an old computer power supply to run them, slapped an air filter on one end, and voila! A 'better than nothin' style air filter. 

It doesn't circulate my whole shop in a minute and a half or anything, but the gobs of dust that accumulate on the filter let me know that it is helping quite a bit!


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## Bob Willing

Gene 

Here is the link http://www.woodworkingtalk.com/f2/air-filtration-system-size-11302/.


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## wolfmanyoda

That's the way I was going to do mine, I have the blower motor and just need to get started.
I was going to run some large flexible duct on the output side to run it to a different part of my garage. My thought was that it wouldn't be pulling the clean air right back in. 
Should I worry about that or just save myself some money?


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## Gene Howe

Bob Willing said:


> Gene
> 
> Here is the link http://www.woodworkingtalk.com/f2/air-filtration-system-size-11302/.


Thanks a lot Bob. That is exactly what I needed!
Sorry for the delay in responding. For some reason, my thread never showed up when I searched for new posts. So, I just figured it was all lost in the "nether regions".
Thanks again.


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## Bob Willing

wolfmanyoda said:


> That's the way I was going to do mine, I have the blower motor and just need to get started.
> I was going to run some large flexible duct on the output side to run it to a different part of my garage. My thought was that it wouldn't be pulling the clean air right back in.
> Should I worry about that or just save myself some money?


IMHO don't worry about ducting. I like mine because it helps to cool off my shop in summer. With my arrangement it blows the exhaust air 12 ft accross the room. When my filters getplugged I take them outside and use a leaf blower to clean them. I only do this about twict than out they go! With the two filters 16 x 20 it equals 4.4 sq ft of filtering area.


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## Bob Willing

Gene Howe said:


> Thanks a lot Bob. That is exactly what I needed!
> Sorry for the delay in responding. For some reason, my thread never showed up when I searched for new posts. So, I just figured it was all lost in the "nether regions".
> Thanks again.


 
Gene when I built the box I attached it to the ceiling first and left the exhaust end open than placed the blower inside and bloted it down than I screwed that side on last. So now if you want to service the blower you can take that side off and remove the blower. I can also manually change the speed by removing one of the filters and the speed change is just a spade lug away.


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## wolfmanyoda

Bob Willing said:


> IMHO don't worry about ducting. I like mine because it helps to cool off my shop in summer. With my arrangement it blows the exhaust air 12 ft accross the room. When my filters getplugged I take them outside and use a leaf blower to clean them. I only do this about twict than out they go! With the two filters 16 x 20 it equals 4.4 sq ft of filtering area.


Fantastic news. 
Now I just have to get out there and build it. Can't use the 'I don't have ductwork' excuse anymore.


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## woodnthings

*Hey wolfman*

Just a thought, here regarding the recycling of the shop air. If you put the exhast and intake on opposite sides/ends of the box you will greatly reduce the recycling effect. An adjustable vane or two to direct the air wood be cool. If you mount the filters on the sides as Bob has done, you do get more filter area, but the commercial ones almost always have the exhaust and intake on the opposite ends. Hey, I'm no air flow guy, but I did work in a wind tunnel a few times at GM, on Richard Petty's race car no 43. :laughing: bill


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## wolfmanyoda

Guess my 'no flex excuse' is back on the table. :laughing:

I actually would prefer to run the duct. I was in another guys garage buying his dust collector and he showed me his homemade setup. His blower was by the garage door and he ran flex to the back of his shop where it entered a plywood box on the wall that had 3 or 4 dryer vents in it for exhaust.
Don't know if I'd mess with the second box though.


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## woodnthings

*Watch out for creating a vacuum low pressure*

Area in the shop if you vent it to the garage. You don't want to create a negative pressure in the shop if that's attached to the house. You may suck down CO from any furnace stacks or water heaters using a gas fired system. :furious: Just a warning. :thumbsup: bill


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## wolfmanyoda

Not sure I'm following you on that one. 
My shop is my garage so if my intake and exhaust are in the same room there shouldn't be a problem, should there?


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## woodnthings

*No problem there*

It's when a shop is in the basement and the air is exhausted into the garage or outside, it creates an back flow in the chimneys and the gases can't escape, so it draws in CO into the house. We had a thread a while back on that issue. Some folks heat their shops with wood stoves or furnaces, so I just threw out the caution flag. :yes: bill


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## wolfmanyoda

Gotcha. 
Yup, garage = shop here. My wife really hates that fact in winter.


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## dbhost

Where are you guys getting the used blower motors to build these?


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## woodnthings

*Heating and cooling contractors and shops...*

Have old furnaces that have been removed from homes during replacement or upgrading. The blowers generally still work. $30.00 to $50.00 should get you a 3 or 4 speed blower, if they won't *give *you one. Start with your heating and cooling contractor. Don't forget to get a wiring diagram, 7 wires that are just dangling can be confusing. (don't ask me how I know this):thumbsup: bill


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## wolfmanyoda

I picked up a whole furnace on craigslist for $25 and took the blower out of it. 
Then I tried to sell a furnace minus blower on craigslist for $25. That didn't work out so well so I gave it away.


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## repeters

Gene Howe said:


> I have a blower from my old furnace that I'd like to use in a box type air filter. Can anybody point me to plans or ideas about building such a unit?
> 
> I'd like to incorporate two furnace filters on the inlet side, if possible.
> 
> Would I simply build the box to accommodate a normal sized set of filters?
> 
> I don't know where to start. All help would be appreciated.
> 
> Thanks, folks!


I found a filter project in a dust collecting book back in 2004 and built it using 3/4" plywood & an old furnace motor I got for $10.00 from a heating & cooling co. near my home. 

I've had it up for years now and it still cleans the air everytime I use it. 

I now have it in PDF form if you want it. 
Just send me your email and I'll send you a copy.

In the mean time, I'll try and put some pics of my unit soon. 
Pete


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## mikro4127

I suggest a direct drive not belt drive, my belt drive bit the dust from long hours running. I made mine out of scrap plywood, made it to fit the same sixe pleated furnace filters for my home furnace so I only had to buy one size. I had 3 intake and one exhaust filter. Use a shop vac to clean them off. You can rotate them around to even out the life. I used mine with a cyclone seperator for a year as my make shift dust collecter until i was able to afford my Delta collecter. Its on caster and has as a slide top box on top with a stop at one end and a tight miter that is lubed with wax to make it slide easier but still seal. I also caulked all the seams.


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## AzULikIt

*DIY air cleaner*

When using a blower motor you should restrict one sine of the blower housing or part of the outlet to put a load on the motor so it draws the proper amps..if not the motor will not be efficient and more that likely burn out before long by loading up the motor you will move more air you will see this by slowly closing off the outlet of the blower with a piece of plywood and you will feel the airflow increase dramatically. when you get the air is at its maximum flow you attach the plywood across the opening at that point


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## SteveEl

mikro4127 said:


> I used mine with a cyclone seperator for a year as my make shift dust collecter until i was able to afford my Delta collecter.


Mikro, I hemmed and hawed about woodcraft's recent online dust collector sale one day too long! (Boo hiss). I'm interested in doing that as my own temporary solution. Could you please post a pic or two? Thanks SteveEl


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## mikro4127

It is currently in storage and not here at home. but as soon as I get to the storage unit I will take some pics and post them.

Its a basic screwed together box, glued and caulked, rectangle openings at each end. The inward side at one time had a generic table saw dust hood screwed and sealed on it, so I could quick connect the hose. I rolled it up to the tool and the seperator. After I bought my delta at the wood working show, I took the hood off and used it as a room air cleaner especially for the small airborn dust etc. Worked like a charm! I got the direct drive motor for free with the squirrel cage from a furnace guy I know. It was an older one he salvaged from a furnace replacement. The filter seperation was simple 3/4" pine stock, made into frames and screwed in on base and sides. I wired a metal swtch box on the side and used extention cord and a plug to wire it all up.


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## burkhome

I have been going to build a down flow sanding table. If you ran that while in the shop it seems logical to me that it would clean the air. Is there an error in my thinking?


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## SteveEl

Oh now i get it.... you're rig didn't do ambient air back when you used it as a work station dust collector, right? I was confused how you made it do both.

Thanks
SteveEl


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## mikro4127

burkhome said:


> I have been going to build a down flow sanding table. If you ran that while in the shop it seems logical to me that it would clean the air. Is there an error in my thinking?


 No error at all burk, you could always combine a down draft table with a room air filter buy putting the filters on top with the intake area and down draft either out the back or bottom, depending on your squirrel cage configuration. I would use peg board on the intake side.


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## BillN

Homebrew supercheap air filter. Take one salvaged box fan, one 20x20x1 furnace filter, one bungee cord, one cheap timer. Mount fan using cleats between ceiling joists blowing up, bungee filter on front. Plug fan into timer and timer into wall set for 2 hours running time. Depending on quality of filter most of the real small stuff is dragged into the filter. Periodically remove filter and run a shop vac over it. It's not as good as real air filter, but for $10.00 it's not bad.


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## ecenur

Gene Howe said:


> I have a blower from my old furnace that I'd like to use in a box type air filter. Can anybody point me to plans or ideas about building such a unit?
> 
> I'd like to incorporate two furnace filters on the inlet side, if possible.


I'm looking into doing something similar to this, did you purchase normal furnace filters and cut and construct from there? How well did it work, was it easy to make?


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## BillN

All your looking to do is circulate the air in the shop and have it pass through the filter media. The finer the mesh the smaller the particle it traps. One could use those expensive HEPA filters, but the difference just using the cheapo filters was so profound that I stopped there. There is no need to over engineer this.


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## repeters

*Air cleaner I built Pic*

This is the one I built for my 20 x 32 work shop. I hung it on the wall opposite the double doors into my garage. I do have the whole article in PDF format if anyone wants it.


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## craigstruzz

*air cleaner intake*

I have a prebuilt cabinet on wheels that I want to use. Does it matter if I place my intake on the side instead of the rear?


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## repeters

*Re: Side filter*

If it's movable, it shouldn't matter. Air flow should not be compromised too much (depending on your filter arrangment). 
Portables are there to collect the dust from a certain machine and your not trying to clean the whole shop. Just be sure that you don't end up blowing other sawdust everywhere causing you to start inhaling it (you should wear a mask when it's on). You could face the exhaust vents up to keep from "cleaning" the floor.
Hope this helps. Pete


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