Garage painters, how do you control where your fresh air comes from?

O

OJ86

Promoted Users
I have a 24" 7,000 cfm fan in my garage. Its mounted under my work bench. It works fantastic no compaints. Well thats not entirely true, my only complaint is that it pulls more air then I can supply which in turns forces it to suck air from every little crack.

Now people have told me to "turn the fan down and I wont have that problem". Well I'm stubburn and I dont want to do that. I like that fact that with the fan at full speed it will(should) cycle the air in my garage every 30 seconds.

On the opposite side of my garage I cut addition roof vents in, but that failed to help.

My plan is to cut out above my garage door, frame and screen it in and on the inside of the garage box it in so I can slide filters in.

What do other garage painters do? I'm just overly cautious about my air quality.

I think tomorrow I am going to turn my fan on, and slowly open the garage door until the shutters are fully open on the fan and that should tell me how big of a hole I need.

Here is a pic of my fan set-up.

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I have a 14" explosion proof fan in the wall about a foot up from your tool box, I picked that location because I thought I would need a second one in the left hand side. (did not)

For air control if spraying clear I raise the two car garage door about 1 inch off the floor and then the fan draws a lot of air, if shooting base I will raise the door about 6" off the floor and it draws less air.
Primers I just leave the door wide open. Seems to work fine for me.
 
For primer I leave the door wide open too, and the amount of trash always seemed minimal. I was afraid to do it this way with top coats, so I am planninng to tape furnace filters together longways across the bottom of my door. I think it will take 4 or 5 filters. I haven't tried it yet, so I'll let you guys know how it works soon.

Do you guys have any tricks for lighting? I have four 4' fixtures on the celiing and six 4' fixtures hanging from the celing vertically on wooden hinges that I made so I can swing them up out of the way when I'm not painting. Still, I doubt I have enough light.
 
strum456;9018 said:
For primer I leave the door wide open too, and the amount of trash always seemed minimal. I was afraid to do it this way with top coats, so I am planninng to tape furnace filters together longways across the bottom of my door. I think it will take 4 or 5 filters. I haven't tried it yet, so I'll let you guys know how it works soon.

Do you guys have any tricks for lighting? I have four 4' fixtures on the celiing and six 4' fixtures hanging from the celing vertically on wooden hinges that I made so I can swing them up out of the way when I'm not painting. Still, I doubt I have enough light.
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Is your door a roll up? if so the top will be open when you roll it up high enough to put the filters on the floor.

I put a pair of vice grips under a set of rollers, then remove the lower panel and put the filters in place of the panel. If I wasn't so lazy i would build a wood frame to hold the filters instead of duct tape, lol.
 
A word of warning! You don't want to pull air thru the attic, unless it is ducted from outside. If the attic has insulation, it will pull the little fibers right thru your "paint booth" and they end up in your paint. Don't ask how I know that.

Aaron
 
Thats my problem. I have direct vents at the front of the garage that bring in fresh air, but they cant supply enough. So I think i am going to blow a big hole on the front of my garage at the peak, screen it, make it look nice and on the inside Ill box it in so it can hold filters.

I'm really trying to make my setup permanent. So when I want to paint I dont have to go through all these steps. Just sweep, water or paper and paint.

I've perfected my setup over the past few years, and everytime I do a big job I see something that I wanna change so the next time its easier. All in all. I HATE setting up, lol
 
I have a large roof peak vent so I thought that would be a good intake area. I could pull the air out low on the wall going into a separate area, then out the window. I figured that would be similar to a down draft booth. Even with good filters, I found out that the fiber glass insulation in the ceiling would provide plenty of little fibers to screw up a good paintjob.

Aaron
 
I pull my air from the main garage area and push it (positive pressure) into the booth through filters and use the roll up garage door similar to Barry's method in controlling the air flow.
In the winter the heated garage air helps with my booth temps and I keep the windows cracked open for fresh air and in summer I just open the windows in the garage area.
Of course, I am not entirely happy with this set up and want to redo the whole thing some time in the future.
I would like to see how real factory booth plenums are constructed and try to duplicate that at home. My air supply side filters have spots where they are drawing air in which means there is an air delivery problem in my "homemade" plenum design.
My booth was originally meant to be temporary for a one time paint job but now is seeing much more usage as I seem to keep getting side jobs.
I have formulas for correct air flow speed and CFM so I already know I don't have enough fan for my booth size.
Lighting is another real concern. I never seem to have enough and there are always "shadows" somewhere on the car that give me trouble seeing what I am spraying.
Another issue is air turbulence caused by square corners in the booth. Since it is a cross draft still the air from the supply filters pushes toward the roll up door and out the bottom and top openings, however the air hitting the main door and end walls on each side of the door begins to roll back toward the front of the booth - not a good thing if you are trying to keep over spray and dust from landing on fresh paint.
 
I had messed around with positive pressure for about a day. I just didnt see the benifit vs the problems it would cause in my setup.

All I really need to do is control where my air gets sucked in at. I can turn my fan down and it works great, but I want to utilize all 7,000 cfm.
 
SOF,

Good idea about taking out the bottom pannel. I was going to cover the top wiith plastic somehow, but I think I'll do it your way. A word of caution to anyone reading: do not attempt to take out the bottom door pannel if you have torsion springs that wind cables to help lift your door (rather than the normal extension springs along the tracks.
 
You will never get one piece of trash in your paint job from not having a filter at the bottom of door.
Dirt comes from car, masking paper and the person spraying the car and the last two feet of air hose hooked to gun that has been rolling around on the floor.
 
strum456;9053 said:
SOF,

Good idea about taking out the bottom pannel. I was going to cover the top wiith plastic somehow, but I think I'll do it your way. A word of caution to anyone reading: do not attempt to take out the bottom door pannel if you have torsion springs that wind cables to help lift your door (rather than the normal extension springs along the tracks.
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YES that is very true, I stick a bar in the winding spring so it cannot rotate when I have dropped the lower panel. I take 2 bars and using one of them wind the spring a bit tighter, then place a second bar in the winder and let that bar rest on the wall. Next I put a pair of "cowboy" clamps on the side rails under a set of rollers. Then I unbolt the hinges on the lowest section and just let it lay on the floor with its rollers still intact. Common sense goes a long ways here. Study the energy potential and control it and all will go well.

Barryk;9059 said:
You will never get one piece of trash in your paint job from not having a filter at the bottom of door.
Dirt comes from car, masking paper and the person spraying the car and the last two feet of air hose hooked to gun that has been rolling around on the floor.
Click to expand...

I am using the filters to capture the over spray before it attaches itself to the neighbors cars, or they see a big cloud coming outta the garage and call the fire dept again. Next time I paint I am going to invest in charcoal filters to help with the odor so the neighbors aren't even aware of my actions.

My latest attempt a booth has a 16" round vent system. I placed it in the bottom of a man door opening. I sealed off the rest of the door opening with plastic.
The 16" round has a nice 90 degree radiused elbow then 10 feet of vertical stack on it. I placed a box fan at the intake end with a standard furnace filter between.

This didn't work as well as I had hoped. The filters under the door worked better.

For intake air I installed a forced air gas furnace on the patio behind the garage, then enclosed it in a 4'x3' "closet" .
The outlet is ducted up and through the garage wall to a main trunk. There are 3 louvered vents off each side of the trunk. these louvers are adjustable for both horizontal and vertical direction. I covered the grilles with intake filter material and gorrila duct tape.

I can run the furnace blower on either hi or low speed, and with or without the gas heat. To control the heat I put a butterball valve after the automatic gas valve and the gas manifold. I can adjust the flame to hold a given output air temp.

Next I am going to add an additional riser duct off the furnace and relocate the trunk into the attic space. I will put 10" branches off it but as of yet have no idea to where ideal would be.
I plan on buildin a box at each grille so I can install a filter before the diffusser vanes for better air direction.

Or would I better off building one log manifold of filter the length of the room and one common filter ?

Where is the ideal location for the air come down at ?










Around the ceiling I have installed a pine 1x2 to staple plastic to . I end up with a work area of 16W x 22L. Cubic volume is app 3200'. The furnace blower is rated at 2650 @ .5wc
 
Bob Hollinshead;9083 said:
Filters do stop bugs though.
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LOL, yea you are right, that is why I will spray nothing at night and I still get a mosquito or nat every so often, depending on time of year.
 
I use to spray boats outside and didn't get much for dirt in my paint. Bugs on the other hand seem to be attracted to fresh paint lol
 
I also use a 24" tubeaxial fan for my booth. I know you don't want to slow it down but mine never worked good until I installed a VFD with a pot switch to adjust speed. I usually run it about 3/4 speed with my filter area. That fan size almost always uses 16 standard 20" by 20" filters. I don't have that much surface area so that is why I think it likes 3/4 speed. For decades the 16 intakes and a 24" fan was the standard. I think you need to slow the fan down or have the 16 filters to work right. When I run mine wide open it sucks through my smaller intake area and picks up velocity. This picks up trash and you know the story. Slow the speed down til it matches my intake and it works pretty good.
 
Here is my setup with filters. I just wanna utilize the 7k cfm to its fullest thats all. I think im going to try one more thing and if it doesnt work then I will live with it pullling less air then I hoped. I'm jsut stubburn sometimes, lol

3674cc4b.jpg


filter6.jpg
 
Is that all the filter surface that you have? Sure don't look like much!

Aaron
 
16x40.

I thought about making the entire portion under the bench a filter wall. Do you think it would help?
 
I would try making the whole thing a filter wall. Your making a huge wind tunnel. You want a steady even flow of air. You want to be able to take a 2' piece of masking paper hung in the middle of the room and watch it barely move. Not flutter and blow all over the place. Your moving an even volume of air at that point that still removes the overspray in the same manner. Also get rid of the furnace filters and use a regular tacky booth filter.
 
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