Ventilation, HVAC for new garage suggestions

[katit]

Here is some background. I have insulated 2 car garage right now. With Ramsond split unit. Works great for cooling and heating, no issue there.

I am building new garage now and I want to solve some issues I currently have. Not sure what would be correct approach.

1. I need to be able to vent garage. I work with brake clean, other fluids, maybe little welding. Wish I could keep it comfort and let fresh air in at the same time.
2. I am going to build small 10x10 or so "paint" room. Planning to do exhaust through window and somehow come up with down-draft air handling. This is to paint small projects, motorcycles, etc.

So, mainly I want to solve air quality problem. Need suggestions on what equipment to use, what to do. Keywords, etc.
Dimensions of "shop" - about 500-600sqft total (including 100ft paint room). Ceiling height from 10 to 12 in different areas

 

[Sawlog]

If you have a conventional hvac system then you can use a ERV energy recovery ventilation system. When your blower on your furnace is on it ***** in air from outside and blends with conditioned air and exhaust stale air from building.
they work great, I have installed them in businesses and homes.
you can also get them stand alone and just use it to exchange air. They have a big filter block in the units that help “condition “ the air on the way in.
some folks just use a bathroom exhaust fan and exhaust it outside and let it put a negative psi on the building , Mother Nature with replace the exhausted air with fresh air through the cracks of the structure.

 

[katit]

If you have a conventional hvac system then you can use a ERV energy recovery ventilation system. When your blower on your furnace is on it ***** in air from outside and blends with conditioned air and exhaust stale air from building.
they work great, I have installed them in businesses and homes.
you can also get them stand alone and just use it to exchange air. They have a big filter block in the units that help “condition “ the air on the way in.
some folks just use a bathroom exhaust fan and exhaust it outside and let it put a negative psi on the building , Mother Nature with replace the exhausted air with fresh air through the cracks of the structure.

What size ERV I need to comfortably ventilate such building? And what kind of footprint do they have? I think I will stay with ductless split system in new garage (for space savings) and just add ERV. But ERV will need ducts, correct? What would be the best supply/return arrangement?

Do you think this system will handle exhaust gas venting? If I want to start car/bike in closed garage?

 

[Sawlog]

Sure, but they are typically only around 120 Cfm. So probably would not keep up with a long vehicle run time but would keep the air exchanging after

 

[PoorUB]

I worked in HVAC for years and thought about this for my home shop and decided there is no practical answer. There is much you can do, but money usually stops that from happening! Even though I could get my hands on used or buy at wholesale prices I never did anything for my shop.

Running a car or motorcycle in an enclosed shop takes a fair amount of exhaust. Best to connect right to the exhaust pipe and vent outside. Using an general exhaust the just removes air from the space will need more CFM and be impractical for a home shop. I have worked on cars and motorcycles for years in my home shop with no exhaust fans. When it came time to run and engine I over head door was cracked open. How far depended on the size of the engine.

An ERV is not a bad idea, but I would not use it as and exhaust fan. They are simply not large enough to do much good, plus you wouldn't want to run a bunch of pain fumes through a $500 ERV on a regular basis. It would just foul up the fans and the heat exchanger.

For your paint booth, just exhaust it outside with a cheap fan and let air in through a partially open door. Anything else to do the job properly will get costly.

I would use a 30,000 BTU gas heater, an electric heater, or a mini-split for heat and figure it will be running hard to reheat the space from time to time while painting or running engines. An HRV or ERV would help keep the air fresh when nothing special is going on.

Actually, once you have a space up to temp and all the mass inside warmed up it takes a lot to cool it back down. Open the overhead door slightly for a few minute and when you close it the shop temps will rise quickly.

 

[katit]

I worked in HVAC for years and thought about this for my home shop and decided there is no practical answer. There is much you can do, but money usually stops that from happening! Even though I could get my hands on used or buy at wholesale prices I never did anything for my shop.

Running a car or motorcycle in an enclosed shop takes a fair amount of exhaust. Best to connect right to the exhaust pipe and vent outside. Using an general exhaust the just removes air from the space will need more CFM and be impractical for a home shop. I have worked on cars and motorcycles for years in my home shop with no exhaust fans. When it came time to run and engine I over head door was cracked open. How far depended on the size of the engine.

An ERV is not a bad idea, but I would not use it as and exhaust fan. They are simply not large enough to do much good, plus you wouldn't want to run a bunch of pain fumes through a $500 ERV on a regular basis. It would just foul up the fans and the heat exchanger.

For your paint booth, just exhaust it outside with a cheap fan and let air in through a partially open door. Anything else to do the job properly will get costly.

I would use a 30,000 BTU gas heater, an electric heater, or a mini-split for heat and figure it will be running hard to reheat the space from time to time while painting or running engines. An HRV or ERV would help keep the air fresh when nothing special is going on.

Actually, once you have a space up to temp and all the mass inside warmed up it takes a lot to cool it back down. Open the overhead door slightly for a few minute and when you close it the shop temps will rise quickly.

Funny how we speak for locale perspective. In my case I actually worry about cooling more than heating I need to heat maybe 1-2mo a year and currently my split unit does it just fine with 450sqft garage. So, to me - cooling and ventilation is a must.

I agree with what you say, this is how I thought about those 2 activities:
1. Running engine - just create direct pipe. Question is.. it won't be used 99.9% of time, having it connect to outside just a "hole" basically. What is a "neat" way to plumb it out and make it "close-able"

2. "Paint boot". I though about exactly what you said. But instead of opening door I was thinking on making door sealed and put couple openings above door and install hvac filters there. So air that enters room get filtered and it comes from main shop. Then I wanted to build some kind of subfloor with ducts (just handful of them ) and install simple hvac fan to such air through sub-floor and outside through the window. Painting is also something I will be doing very rare and I just need clean air and ability to work inside room (not outside like today)

What about using solvents, glues, etc. Is ERV good enough to keep air clean in a shop? That is somewhat most important to stop breathing all this stuff.

 

[PoorUB]

As for the booth you don't need a sub floor. Run duct down thorough the stud bays, and have them meet over the top of the room and run to a fan. You can buy oval duct that fits in a 2x4 stud walls, or perhaps even 4" round might be enough if you run enough of them. I might put a small work bench in the paint booth and use it for cleaning carbs and stinky stuff. Try to keep most solvents out of the general garage, impossible, but cut it down a lot.

An HRV or ERV will help, but it will not ventilate and area in minutes. Most or them are 60 to 150 CFM. Your 600 square foot garage is maybe 6,000 cubic feet so a 60 CFM unit is one air exchange every 100 minutes, a 150 CFM every 40 minutes. You can buy an HRV/ERV with a low speed fan setting so it could run constantly at 50 CFM and you can flip a switch to ramp it up to 150 CFM when you are working out there. If you are on the fence to how big of mini-split to buy I might go up 1/2 ton, 6,000 BTU to help cover the fresh air.

 

[katit]

As for the booth you don't need a sub floor. Run duct down thorough the stud bays, and have them meet over the top of the room and run to a fan. You can buy oval duct that fits in a 2x4 stud walls, or perhaps even 4" round might be enough if you run enough of them. I might put a small work bench in the paint booth and use it for cleaning carbs and stinky stuff. Try to keep most solvents out of the general garage, impossible, but cut it down a lot.

Great idea! How do I make it "one way" exhaust so it's seals when not on? I think if it ***** on bottom wall - not too much worse vs direct down.

And I also thought about placing cleaning tank and powdercoat oven all in a same room. So all the dust and solvents going to be in one place with powerful exhaust. It's just paint booth and desired "cleanliness" bothers me.

OTOH, if exhaust is powerful enough - no equipment will get overspray and technically should be fine?

For general work area - ERV + Split should be just fine.

 

[PoorUB]

You will get overspray on any equipment in the booth, no avoiding it other than to cover it while painting. When you build it make sure you consider how to clean it. I might use fiberglass reinforced panels so you can just wash it down.

You can buy backdraft dampers for most any common size of duct.

 

[katit]

You will get overspray on any equipment in the booth, no avoiding it other than to cover it while painting. When you build it make sure you consider how to clean it. I might use fiberglass reinforced panels so you can just wash it down.

Yes, it's another question. And drain too. Definitely not going to have sewer, maybe install some kind of sump?

For washing, maybe just paint walls with some kind of washable paint? Not sure but might be cheaper than panels. And, need to figure out lights too. Lot of lights.

 

[PoorUB]

I wouldn't worry about a sump or drain. In your part of the country just put a gradual slope to the middle and to the over head door. push the water outside. You could put in a floor drain to a sump that you can just pump out into the yard.

 

[katit]

I wouldn't worry about a sump or drain. In your part of the country just put a gradual slope to the middle and to the over head door. push the water outside. You could put in a floor drain to a sump that you can just pump out into the yard.

Not really. This is "booth" - room will be completely enclosed, no overhang door and the only door is going to go into shop area. And no way to put drain in there (unless I plan on it now..)

 

[PoorUB]

Not just slope the booth, the whole garage. As long as you don't have a bunch of clutter on the floor, hose it down and squeegee it out.

 

[katit]

Whole garage IS sloped. But booth will have walls around. So, nowhere to push water

 

[PoorUB]

It will have a door?

 

[katit]

It will have a door?

Yes, but it will not be done in a way that it's going to be easy/convenient to push water outside.
Garage is 37x37 (approx) and there going to be double door on left and single on right. Left "bay" will be walled about 22x22 for regular parking, etc. and remaining L-shaped section will be my shop. Booth will be in top left