Garage Ventilation.

[Mike65]

I did a search but did not find an answer to my question so here goes. I have a 24'x25' metal garage that is insulated with 2" of spray foam & the 2 roll up garage doors face south. One side of the garage is mostly shaded by the house/carport & the other side is shaded by large pine trees. In the summer it gets hot here in southern Virginia averaging the low 90's & it is unbearable to work out there. The walk-through door is in line with one of the garage doors so I prop open the door for some cross breeze but is usually not much & if there is any you only feel it if you are in line with the open doors. I was wondering if I installed a gable exhaust vent like in the attached link if it would help?

https://www.amazon.com/gp/product/B08X4KNB36/?tag=atomicindus08-20

https://www.amazon.com/gp/product/B09LCH7NY8/?tag=atomicindus08-20

Here is a pic of the inside of our garage.

 

[ctandc72]

In VA as well. Friend had the same problem. He added a vent / exhaust van like that, plus a shop fan couple of years ago. He said it helped, but finally he just broke down and cut a hole in the building and installed a window AC.

 

[loganb]

I agree, exhaust will help but you have a well insulated and tight structure...the right answer is conditioning the inside. 12k minisplit or a big window unit if heat isn't needed/desired and you're going to be far more comfortable.

 

[CombatNinja]

If you're hot in a building that is mostly shaded and has 2" of foam, there is nothing you are going to be able to do short of proper HVAC that will make you comfortable. That building is not too large, a ductless minisplit with 2 cassettes should be able to take care of that no problem. You wouldn't even have to keep it set down super low and consume a ton of electricity, just setting it to 77-78 degrees and letting it dry the air will help you out tremendously. It's probably the humidity that is getting to you more so than the actual air temp. Your body simply can't cool itself when your sweat won't evaporate.

 

[CraigStu]

It always helps to get air moving but in addition to the gable fan you need an air inlet. And that inlet may be able to be positioned where it is out of the sun the most. But even then, you are just sucking in ambient temp air. I agree w/ loganb. With your metal garage walls it may be a little extra work but I second the window AC unit. I cut a hole in the wall of my attached 3car stick frame garage to install one. It is a lifesaver. I even found one that runs on 120V so didn't need to run a 240V outlet. Mine isn't rated to do the entire 3car Sq ft but it cuts humidity and I sometimes use a floor stand mounted oscillating fan to move the air around a little more.

 

[Mike65]

Thanks for the info guys. I will have to save up for an a/c system.

 

[bb29510]

get a window unit, build you a four foot wall to go under one of your doors and close down on top. then you be ablle to see if its worth it before cutting metal

 

[CraigStu]

I was in mine yesterday and today in 88degF. That window Ac made it very pleasant even though it never got down to the 75F I have it set to.

 

[CombatNinja]

You guys undersizing your HVAC are just being hard on the equipment. It will fail prematurely. I live by this adage when it comes to purchasing anything that is even moderately a pain in the **** if it fails: buy once, cry once.

 

[SpiderDave]

I did a search but did not find an answer to my question so here goes. I have a 24'x25' metal garage that is insulated with 2" of spray foam & the 2 roll up garage doors face south. One side of the garage is mostly shaded by the house/carport & the other side is shaded by large pine trees. In the summer it gets hot here in southern Virginia averaging the low 90's & it is unbearable to work out there. The walk-through door is in line with one of the garage doors so I prop open the door for some cross breeze but is usually not much & if there is any you only feel it if you are in line with the open doors. I was wondering if I installed a gable exhaust vent like in the attached link if it would help?

https://www.amazon.com/gp/product/B08X4KNB36/?tag=atomicindus08-20

https://www.amazon.com/gp/product/B09LCH7NY8/?tag=atomicindus08-20

Here is a pic of the inside of our garage.

Nice shop! Are you asking if the fan will make it cooler or just move enough air to equalize with the outside? By that I mean, is it tolerable outside but too hot in your shop with the heat pooling up and nowhere to escape? A split system is a great remedy AND it'll heat your shop in the winter too. But if that's not in the budget, a gable fan and an open area (like a vent, open door or window) for air to come back in will do wonders.

If you're just looking to exchange air, either of those fans will work. The one that's a higher cfm might even be more than you need, but it can't hurt either. Just make sure you have a larger opening letting air back in.

 

[ycgoat]

I use a 30” fan that I roll around to blow directly onto me when it gets that hot, and take lots of breaks to sit down and hydrate

 

[nadogail]

I open the big door on the North side and the man door on the South side. I have a pedestal fan when it gets uncomfortable.

 

[Mesozoic]

This year's been pretty hot, although I'm not sure if the media is exaggerating it or not. It's always darn hot in southern Arizona during the summer and the temperatures have not exceeded some of the record I've seen broken in years past.

In any case, my garage is pretty hot unless I'm running the 2 ton HVAC. Of course, the cost to run the HVAC is a consideration, so unless I'm working on a project I leave the system off (which is most of the time). During the course of the week, with hot cars and motorcycles being parked within the temperatures can soar up to 100*F inside the garage. The ambients are typically in the high-70s to 115*F range throughout the day. I insulated things very well, so the garage seems to trap the heat well which isn't great for when I feel like tinkering on something for an hour or so on any given evening.

My solution is to exhaust the hot air within the garage, which gets trapped up top and is caused by hot vehicles parked within. I'm planning to install an electronically controlled barometric damper (size of which I still need to calculate) low on one end of the building. The other end of the building gets a ceiling mounted 2000 cfm dual blower (squirrel cage) exhaust blasting out the side of the building (high up). It might be overkill, but some rough calculations show that I should be completely changing the air in the space every 5 minutes this way.

 

[FL Guy]

Ive got an exhaust fan in my garage with foam. It helps with sucking all the weld smoke out. It's a 30" fan and I can turn all the air over in the garage once every 2 minutes. You'll need about 20 square feet of opening. So a walk in door open would work or open your garage doors about 1-2'

 

[bb29510]

Ive got an exhaust fan in my garage with foam. It helps with sucking all the weld smoke out. It's a 30" fan and I can turn all the air over in the garage once every 2 minutes. You'll need about 20 square feet of opening. So a walk in door open would work or open your garage doors about 1-2'

is that mounted correct?

 

[FL Guy]

is that mounted correct?

Why wouldn’t it be?

 

[Mesozoic]

With welding, you certainly need to turn the air over as frequently as you are, so good on you for accomplishing that.

My situation is a little bit more complicated simply because the shop can run in an air conditioned mode. The fresh air system needs to be able to close itself off completely when the HVAC is on.

1. HVAC OFF: The garage needs ventilation to turn over the air based on heat and fume buildup exacerbated by hot vehicles parking inside.
2. HVAC ON: The fresh air ventilation needs to close and seal itself off to avoid wasting energy.

I think electronically controlled dampers are the only way to achieve this and it still won't turn over the air as frequently as a massive 30" inch fan. I seem to be stuck on wanting to use a dual squirrel cage setup running about 2000 cfm for some reason... I have no idea why.