exhaust fan recommendations

[Cameron]

So in my new garage build there will be a sectioned off area that is 24' deep, 11' high, 12' wide. This will be directly in front of one of the garage doors which will be used for fresh air supply. On the opposite side I will mount a fan to extract the overspray. At ~3100 cubic feet, I'm thinking if the fan were to exchange the "booth" 1-2 times per minute that should be ok.

Does this sound about right? I'm leaning towards the 16" or 20" Jenny fan that Len has here.

Thoughts welcomed.

Cameron

[drminpa]

Its not the number of air exchanges that counts. Its the air velocity. You need an even air flow with little turbulence to sweep the overspray away. The OSHA standard is 100 liner ft/min. You can probably get away with half that for a home booth (that's what I'm designing mine to). Your planning a cross flow design so your cross section is 11 X12 or 132 sq ft. At 50 ft/min, you need 50 X 132 = 6600 cfm (the high ceiling is somwhat of a detriment). Using the garage door for the inlet should work fine - you will want to have at least 50 sq ft of filter area at the inlet.

[Cameron]

I plan on creating a structure that will allow the garage door to open at the bottom but will deflect filtered air at ~7 feet off the ground. I'd also planned on having the exhaust fan somewhat low on the wall but don't know what the ideal height would be.

Any thoughts welcomed.

Cameron

[alaskajeff]

I plan on creating a structure that will allow the garage door to open at the bottom but will deflect filtered air at ~7 feet off the ground. I'd also planned on having the exhaust fan somewhat low on the wall but don't know what the ideal height would be.

Any thoughts welcomed.

Cameron

I'm not an expert, but I'd bring fresh air in as high as possible (7' sounds pretty good) and exhaust as low as possible in a cross-flow setup. If the exhaust is in the wall, I'd put it at floor level. Most of your bad stuff is heavier than air.

[drminpa]

I plan on creating a structure that will allow the garage door to open at the bottom but will deflect filtered air at ~7 feet off the ground. I'd also planned on having the exhaust fan somewhat low on the wall but don't know what the ideal height would be.

Any thoughts welcomed.

Cameron

Deflecting air will more than likely cause turbulence which will cause overspray to swirl and be deposited all over you booth rather than be drawn out. I'd let it flow naturally. Having the inlet high and the outlet low should create a bit of down draft which I think would help with your high ceilings. Also, you want a large inlet filter area to keep the turbulence minimal (think standing in a gentle breeze instead of in front of a shop vac hose).

[Cameron]

My plan is to open the garage door about 18", then have an open topped box of sorts that would fit tightly against the open door. The open top of this box would be 7' from the floor. Imagine a large rectangular duct that moves the 18" x 8' wide door opening to 7' above the floor. So, air enters at the top, leaves low. I'd like to create some sort of open duct work for the fan side to have the air exhaust low without creating turbulence. Has anyone ever done this sort of thing?

Cameron

[joelk]

I'm planning to use a garage bay of similar size as a paint booth.

I have a 10' wide by 7' tall 2" thick garage door. The door has 4 panels, each about 21" tall. I plan to remove the third panel up from the floor, and replace it with a panel made out of 1/2" plywood, 2x4s and filters. Plywood + 2x4s will be very similar in thickness to original door panel and I expect the door to operate normally with the filter panel installed.

I installed the garage door and it is no big deal to remove and replace a panel. With a nutdriver on a cordless drill, I should be able to swap between the original panel and the filter panel in just a few minutes.

I considered partially opening the door and trying to place filters and some kind of makeshift seals in the open area but I think substituting a "filter panel" is a MUCH better solution. You could replace 2 door panels if you feel more filter area is needed.

[joelk]

I created my garage door "filter panel" (FP) and installed it yesterday. I have not yet painted with it, but it seems like it will work very well, at least based upon the amount of filters I was able to install. I would prefer to have more filter area and I may make another FP and install 2 in the door.

I created it with 2X4s, 5/8 plywood and some 1x3 trim around the filters. I put some weatherstrip between the FP and OEM panels still in the door. I used 4 16x25x1 furnace filters, as this is what would fit in the openings between the 2x4s.

When I got done with it, it weighed more than I expected and more than the OEM door panel, I was concerned that this might be an issue with the GD opener, but it handled it just fine.

If I build another one, I would probably change the materials list somewhat, in order to reduce weight and increase filter area. I would definately use 1/2 plywood (I used 5/8 just because I had some scrap lying around) I would either use 2x3s, or cut down the 2x4s in areas where the filters would go, so that I could install larger filters, perhaps 19x25s. I would then use a smaller trim around the filters.

It took a good bit of time to construct the FP, but removing the stock door panel and installing the FP took about 15 minutes. Now that I have the mounting holes drilled in the FP, I feel certain I can easily swap them in and out in less than 10 minutes.

[driven1]

can we get pics of you guys setup?

Greatly Appreciative

[68Jcode]

I'm interested in photos of the 'filter panel' as well.

I'm planning a similar setup, but I plan to put the filters in place of the top panel of my door, and exhaust low on the back wall of the garage. Seems simpler to me to remove the wheels from the top panel, tip it back and put the filter panel in place there, as opposed to replacing a panel in the middle of the door.

[joelk]

Sorry, I don't currently have a digital camera to take/post pictures. If I get/borrow one, I'll post photos.

I think putting the panel in the middle is probably easier than putting it on top if you have a GD opener (and maybe even if you don't) Using a middle panel/s you don't have to mess around with the "bar" that connects the opener to the door..

Significant time involved in creating the panel, but removing the OEM panel and installing the filter panel was very easy.

[68Jcode]

I hadn't really considered the fact that the garage door opener would be holding up the top panel while you removed one of the lower ones. Sounds like a good idea.

[joelk]

When I installed the filter panel, I closed the door, took out the screws that hold the hinges to the middle panel, ran the opener briefly till it lifted the top panel away, took OEM panel out, put the filter panel in (put weatherstripping on top and bottom to seal) ran the opener to bring the top panel down, and reinstalled the screws.

Works great and I have run the door (with filter panel installed) up/down dozens of time since it was installed. Operates just like the OEM door.

One caution: The filter panel may make your garage more susceptible to break in, especially if the they can just reach through the filter opening and push the garage door opener button. You may want to relocate the button if it is within reach.