How I heat my paint booth

S

Senile Old Fart

Lets qualify this by stating I don't have a paint both per say, but it is an enclosed area I paint in. right or wrong - its what I have to work with.

I have a 2 1/2 car garage, fully insulated , drywalled,taped & textured. It has an 18' door and a 3' door on one end, on the other end is a 3' door.
Along the ceiling in an area app 18'w x 22'l I have screwed a 1"x2" pine strip.
From this strip I staple a continuous piece of white 6 mil plastic that drops to the floor.
I cover the floor with another piece of this plastic and then duct tape the 2 pieces together along the floor line.
There is an overlap area that corresponds to the rear 3' entry door, which I close by rolling the plastic over it self and clamp with a few spring clamps.
Next time I set it up I am going to install one of the zippers that are sold for plastic sheeting.
At the 3' entry door on the front wall I have a plywood insert that mounts in the casing where a screen door would mount.
This piece of plywood has a 16" diameter hole in it at floor level. On the exterior side there is a 2' length of round duct, a 90 degree elbow and 10' length of vertical duct.
I cut and tape an opening in the plastic sheet at the opening in the plywood.
I place a box fan that is surrounded by 20"x20" filters in a 4 sided configuration with the fan running on high in front of the air outlet opening . The box fan has a cord that is ran to an exterior outlet which I plug in and unplug so there is no switching action done in the "booth".


Now for my supply side of the ventilation.
I installed a used natural gas forced air furnace on the patio behind the rear wall of the garage. It is an up flow furnace so the duct coming off the top of the furnace runs up to ceiling height, then passes through the back wall of the garage and continues for 16 ft across the ceiling towards the front wall.
There are 6 1'x1' diffusers, 3 on each side mounted to the side walls of this 20" x20" duct.
The intake side of the furnace (which is the cold air return in a closed loop system)has a set of flanges added to accept filters.
The furnace has had walls built around it to hide it. Above the 3' entry door to the furnace I mounted 2 large gable end vents.
I can run the furnace on either of its 2 speeds and with or without the burner running.

I can pressurize the garage to the point where the 18' wide door is severely bulging- woops. wont do that again- remember to open the door to the exhaust stack first .

LEGAL DISCLAIMER: DO NOT DO THE FOLLOWING TO YOUR FURNACE.

To control the heat output of the furnace I have modified the gas train. I mounted a gas rated ball valve between the automatic gas valve and the gas manifold. I use this valve as a throttle to control the amount of gas available to the burner manifold. This configuration does not alter the pressure settings of the regulator or any of its functions, it just restricts the flow to the burner.. think of a gas bbq grille, they are configured the same basic way.
I do not use a thermostat, I just set the burner, if needed, to a level that maintains the desired heat in the garage/booth.
This is not the perfect arrangement as the air is discharged in a horizontal direction from the middle of the room. I think it would function better if the discharges were nearer the outer "walls".
My next step is going to be to mount the existing trunk line in the garage attic and run branch lines off of it and have the diffusers mounted in the ceiling in a more outward location.

I have not used this system in single digit temps and do not think it could keep up. The furnace is rated for a 60 degree temp rise at 2200 cfm.

Rusty's furnace thread has me thinking.
When I move the duct work I will have to raise it 28 inches up to get into the attic,this will require an additional section of duct installed on the air discharge plenum.
This new section of plenum would be a great place to hook up a 10" round and bring down to floor level where a torpedo heater could be directed into it.
A tee added to the mud drip leg of the existing gas line will provide the fuel. A gas hose and QD to connect to the torpedo and I will have auxiliary btu's when needed.

Thanks Shine for the idea of using a torpedo heater.

My question to the pro's : where would the optimum location be in my booth for the relocation of the air diffusers?

btw, for normal work in the garage I have a 40k btu nat gas unit heater hanging from the ceiling that is thermostatically controlled, normally set at 45 to melt the snow off the wifes car, and keep my 02 Vette nice and cozy under its cover,lol.
 
Wow. Quite a set up.

I use waste oil to heat the shop, natural gas furnace in the booth. I turn both off to spray. I do leave the infared on to keep the metal surface warm and let solvent out



.[video=youtube;EXx-OSZlj-0]http://www.youtube.com/watch?v=EXx-OSZlj-0[/video]
 
Hey SOF, where did you get the white 6 mil plastic? All I've found around here was either clear or black, but that was over 8 years ago. White would be much better I would think. Thanks
 
i just redid the blast booth with white greenhouse plastic. you can get it at a greenhouse supply. i bought from Growers Supply on line. they sell by the ft. most want to sell 100 ft rolls .
 
old soul;3570 said:
Hey SOF, where did you get the white 6 mil plastic? All I've found around here was either clear or black, but that was over 8 years ago. White would be much better I would think. Thanks
Click to expand...
concrete construction supply house, its used for vapor film under a pour.
 
what did you have to pay ? i bought 25 ft of 40 ft wide . was 5.37 a ft . has a 4 year warranty to uv so i thought it should last a while inside.
 
First off, No problem with the ball valve "adjusting" the gas flow.It won't matter weather it's on the inlet or outlet side of the gas valve.Main consideration is your burning the gas AT the burners correctly.As long as you have a good BLUE flame with a little YELLOW tipping,your good,WHITE is BAD.Thats when you start sooting as well as creating a CO hazard.
Now,NO WAY would I hook a torpedo heater to ANY type of ducting.
They run way too HOT on their outlet and will overheat the duct as well as melt any type of tape used at the joints.
These are best used free standing and the air heated from them pulled into the "booth".You could use it to reheat the furnace intake air but I'm a little confused on "where" it's coming from.If it is from the garage in general,just let it blow into there and let the furnace intake suck it in.Rember that you also have to provide air back INTO whever you exaust it from of equal volume,Otherwise you create a negative pressure and suck in air from ANY place it can come from.Ever open a door to a restaurant and feel the air rush in? Kitchen ex fan and little/no make up air.
As for you supply grills,Yes outside "wall" location is best as this is where your heat loss/gain is from as well as not blowing directly onto your paint work and add a couple more on each side,your dumping a LOT of CFM (volume) as well as FPM (feet per min,force) thru these which can stir up any trash or dust. You want the CFM but less FPM as you want to have the ex. fan equal to or slightly more to pull the fumes out as well as less air blowing out to stir up or blow trash off the floor or you.
 
stuff is good for an outdoor space too. it usually last about 7-8 years on the green house. it really lit up the blasting booth. my lights are outside of the booth .
 
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