Garage vent exhaust fan, mini-split, etc?

[jeromedawg]

Hey all

Looking for the best way to keep our attached garage cool and comfortable especially in hot weather. Its built into the house so there are bedrooms above btw. I believe the garage door is insulated but there are windows that allow light in. Its also west (and slightly south) facing. There is a small 1x1'~ vent there - would adding an exhaust fan in that vent make sense? I'm not sure if the garage walls would be insulated so would we want to insulate them if not? Would a mini split, portable ac or evaporative cooler be effective? I plan to build out a work bench in there and would like to be able to go into the garage without sweating after several minutes haha. Its not too bad when the weather is cooler but if it warms up even a little it isnt very comfortable working in there.

[nereo]

First, it’s important to establish whether the garage is inside the building envelope, or outside it.  Most garages are outside teh building envelope (even attached ones).  Given that there’s a passive vent it’s exterior - (also possible) someone didn’t understand basic building science and made the mistake of trying to do both (and accomplishes neither). 


The easiest and most ‘green’ solution would be to keep your garage exterior of your building envelope, and to increase the ventilation. A single 1x1’ vent is inadequate for a space that’s likely ~500 square feet. Ideally you’d want cross ventilation, and a lot more of it.  This is pretty easy to accomplish - just carefully cut a few vent holes in between the bays and attach additional vents.  While you are doing this you should verify that the ceiling of the garage (which is the ‘floor’ of the upstairs bedrooms) are insulated, as are the interior walls to your house.  The exterior garage walls do NOT need to be insulated, and in fact they should not be. Moisture and vapor drive are the enemies here, and ‘a little’ ventilation will give you more problems over decades than ‘lots’. Ventilation is also very important if that’s a space where you store the typical gas engines, paint cans, herbicides and other harmful and flammable substances


You can also turn the garage into a conditioned space (move it inside the building envelope, and add air-flow to the rest of the home).  This is a bigger undertaking, as you have to consider how you are going to handle vapor diffusion,  and airflow. It will likely mean sealing up that vent entirely, checking (and possibly adding) a vapor retarder to the exterior walls, and connecting it to your HVAC system and/or humidity control. If you go this route you definitely don’t want to be storing gasoline or similar items in your garage.   It will also almost certainly make your home less energy efficient, as you will be heating/cooling a larger space, and garage doors are notoriously leaky.

[chemistk]

Around here, when it's really hot (mid-Atlantic), most unconditioned vehicle service shops will keep the bay door 3/4 closed and either have a high power fan at or near the roofline, or they'll have huge air-mover floor fans pulling air from the bottom of the bay door and directed inside but away from the workspace.

The key is to be able to circulate a high enough volume of air to enable a sufficient convection current, but not so much air that everything's blowing around everywhere.

I think there are two good options here:

1) Bite the bullet and spend a few grand on a minisplit. You could DIY it using a model with precharged lines for very cheap, but if you're uncomfortable dealing with the electrical then you could always have someone come out and do it.

2) Install one or more fans - I'd think, if it's feasible, a ceiling fan coupled with a vented exhaust would give you the best air circulation. It'll never get to be comfortably cool but it should be drier and less stagnant and make the space somewhat comfortable to work in.

[Uturn]

My last house had an attached garage and the exterior walls were not insulated.  I insulated them and ran two new 20amp circuits while the drywall was down.  I then tapped into the HVAC plenum and ran a vent to the garage.  I did not run a return.  This kept the garage above around 45 in the winter and around 85 in the summer.  I also ran a dehumidifier in the summer.  I did not notice a change in my power bill nor a change in comfort level in the house.  This was in N. TX.  It technically did not meet code because car exhaust now had a path into the house, but I don't park cars in the garage.

My current house has a detached garage that was just open studs when I bought it.  I put in 4 outlets in the ceiling on two circuits and hung retractable extension cords from the ceiling.   I love not having cords running across the floor!  I insulated and put up drywall, and installed a mini-split heat pump.  Holy crap that thing is nice!  Last winter my power bill change was negligible.  This summer, it probably cost $40-50 per month to run it. 

I do woodworking and average about 10-15 hours per week in my garage. 

[BlueMR2]

I put insulating blinds on the window in the wall and then also covered the garage windows with a lightweight thin insulation (left over from my BatticDoor kit that I used to insulate my whole house fan opening).  Makes a large difference in the Summer with keeping garage temperatures down.  In the Winter the garage door windows used to ice up on the inside, now they don't (no condensation behind the insulation at all).

[Papa bear]

First, it’s important to establish whether the garage is inside the building envelope, or outside it.  Most garages are outside teh building envelope (even attached ones).  Given that there’s a passive vent it’s exterior - (also possible) someone didn’t understand basic building science and made the mistake of trying to do both (and accomplishes neither). 


The easiest and most ‘green’ solution would be to keep your garage exterior of your building envelope, and to increase the ventilation. A single 1x1’ vent is inadequate for a space that’s likely ~500 square feet. Ideally you’d want cross ventilation, and a lot more of it.  This is pretty easy to accomplish - just carefully cut a few vent holes in between the bays and attach additional vents.  While you are doing this you should verify that the ceiling of the garage (which is the ‘floor’ of the upstairs bedrooms) are insulated, as are the interior walls to your house.  The exterior garage walls do NOT need to be insulated, and in fact they should not be. Moisture and vapor drive are the enemies here, and ‘a little’ ventilation will give you more problems over decades than ‘lots’. Ventilation is also very important if that’s a space where you store the typical gas engines, paint cans, herbicides and other harmful and flammable substances


You can also turn the garage into a conditioned space (move it inside the building envelope, and add air-flow to the rest of the home).  This is a bigger undertaking, as you have to consider how you are going to handle vapor diffusion,  and airflow. It will likely mean sealing up that vent entirely, checking (and possibly adding) a vapor retarder to the exterior walls, and connecting it to your HVAC system and/or humidity control. If you go this route you definitely don’t want to be storing gasoline or similar items in your garage.   It will also almost certainly make your home less energy efficient, as you will be heating/cooling a larger space, and garage doors are notoriously leaky.

I agree with everything here except for connecting the garage to your current hvac. 

Unless you are turning this into living space, do NOT connect it to your forced air system.  You risk the chance of not only fumes from bad stuff (listed above) but also carbon monoxide from vehicles.   Remote starts have been known to go off in a garage, and this could be deadly. Adding ductwork to the garage also can increase the fire hazard.  The wall between house and garage should be more fire resistant than the rest of the house.  Adding ductwork compromises that system. 

If you want to insulate the garage and condition it, use a separate hvac source and keep air exchange to an absolute minimum between that space and your living space. 


Sent from my iPhone using Tapatalk

[ChpBstrd]

If you're using the garage to park vehicles, it may be a lost cause to keep it comfortable because you're pulling probably 500-600 pounds of super-hot engine and exhaust metal, plus a thousand pounds of sun-baked auto body, in there every time you park. Additionally, I'd be reluctant to spend money on a mini-split, just to spend money on the electricity to run it, just to keep the car-hole cooler. That's like paying money for gasoline to burn, and then paying money for electricity to remove the heat from the burned gasoline!

That said, you'd like to have some tolerable workshop space. The cheapest way to accomplish this is a window AC unit that you only turn on during projects. A used model will suffice because it will only be used intermittently anyway. The upside is that such an AC could be bought for $50-100 used and popped in a window with no professional labor needed. The downside is if your garage lacks a window! In that event, I would work really hard to see if I could figure out how to route a hose for one of those floor-sitting AC's that utilize a window. E.g. could you route such a hose to an outdoor dryer-type vent through the roof gables or soffits? Otherwise, you could just hack a hole in a wall for the vent.

Lastly, if the main reason you don't use the workshop with the garage door open is bugs, maybe consider those garage-door-sized screens that are popular in Florida.

[jeromedawg]

If you're using the garage to park vehicles, it may be a lost cause to keep it comfortable because you're pulling probably 500-600 pounds of super-hot engine and exhaust metal, plus a thousand pounds of sun-baked auto body, in there every time you park. Additionally, I'd be reluctant to spend money on a mini-split, just to spend money on the electricity to run it, just to keep the car-hole cooler. That's like paying money for gasoline to burn, and then paying money for electricity to remove the heat from the burned gasoline!

That said, you'd like to have some tolerable workshop space. The cheapest way to accomplish this is a window AC unit that you only turn on during projects. A used model will suffice because it will only be used intermittently anyway. The upside is that such an AC could be bought for $50-100 used and popped in a window with no professional labor needed. The downside is if your garage lacks a window! In that event, I would work really hard to see if I could figure out how to route a hose for one of those floor-sitting AC's that utilize a window. E.g. could you route such a hose to an outdoor dryer-type vent through the roof gables or soffits? Otherwise, you could just hack a hole in a wall for the vent.

Lastly, if the main reason you don't use the workshop with the garage door open is bugs, maybe consider those garage-door-sized screens that are popular in Florida.

So right now, admittedly and unmustachianly, we can't park in the garage because it's full of stuff lol. I'm planning to better organize things though once we have our HVAC system changed (this involves a portion of ductwork being removed that is blocking otherwise 'precious vertical real estate'). Once we get to the point that we can park one or both cars in it, and if I did want to go into the garage to do any work etc, I would most likely pull at least one or maybe both cars out depending on what it is I plan to do. I would also try to avoid going out there after just having pulled a car in. I figure if it's something like where I want to work in the garage in the AM and the car has been sitting overnight and cooled down, it's probably not as big of a concern.
We are getting solar so there's that as far as the concerns with spending more on electricity (well, assuming we don't run it so much and so often that it pushes us outside of our solar generation capacity, which I would doubt).

In terms of the portable floor AC units (non-evaporative I presume?), I could route the exhaust hose up to the small vent I described earlier. I don't know if it's advisable to route an exhaust vent like this *upwards* however. And I would just have a drain hose exiting out by the garage door (although with this too I don't know if a long drain line is advisable). The concern is that the vent is approx 15-20' or so away from the garage door, so I'm not sure what's more important as far as placement is concerned - should the AC unit be positioned for a shorter exhaust hose length or for shorter drip/drain line length?)

As far as bugs, that would be a concern as we have mosquitoes around here (especially in warmer weather). I've never seen those garage door screens so that might be something interesting to look into.

[ChpBstrd]

If you're using the garage to park vehicles, it may be a lost cause to keep it comfortable because you're pulling probably 500-600 pounds of super-hot engine and exhaust metal, plus a thousand pounds of sun-baked auto body, in there every time you park. Additionally, I'd be reluctant to spend money on a mini-split, just to spend money on the electricity to run it, just to keep the car-hole cooler. That's like paying money for gasoline to burn, and then paying money for electricity to remove the heat from the burned gasoline!

That said, you'd like to have some tolerable workshop space. The cheapest way to accomplish this is a window AC unit that you only turn on during projects. A used model will suffice because it will only be used intermittently anyway. The upside is that such an AC could be bought for $50-100 used and popped in a window with no professional labor needed. The downside is if your garage lacks a window! In that event, I would work really hard to see if I could figure out how to route a hose for one of those floor-sitting AC's that utilize a window. E.g. could you route such a hose to an outdoor dryer-type vent through the roof gables or soffits? Otherwise, you could just hack a hole in a wall for the vent.

Lastly, if the main reason you don't use the workshop with the garage door open is bugs, maybe consider those garage-door-sized screens that are popular in Florida.

So right now, admittedly and unmustachianly, we can't park in the garage because it's full of stuff lol. I'm planning to better organize things though once we have our HVAC system changed (this involves a portion of ductwork being removed that is blocking otherwise 'precious vertical real estate'). Once we get to the point that we can park one or both cars in it, and if I did want to go into the garage to do any work etc, I would most likely pull at least one or maybe both cars out depending on what it is I plan to do. I would also try to avoid going out there after just having pulled a car in. I figure if it's something like where I want to work in the garage in the AM and the car has been sitting overnight and cooled down, it's probably not as big of a concern.
We are getting solar so there's that as far as the concerns with spending more on electricity (well, assuming we don't run it so much and so often that it pushes us outside of our solar generation capacity, which I would doubt).

In terms of the portable floor AC units (non-evaporative I presume?), I could route the exhaust hose up to the small vent I described earlier. I don't know if it's advisable to route an exhaust vent like this *upwards* however. And I would just have a drain hose exiting out by the garage door (although with this too I don't know if a long drain line is advisable). The concern is that the vent is approx 15-20' or so away from the garage door, so I'm not sure what's more important as far as placement is concerned - should the AC unit be positioned for a shorter exhaust hose length or for shorter drip/drain line length?)

As far as bugs, that would be a concern as we have mosquitoes around here (especially in warmer weather). I've never seen those garage door screens so that might be something interesting to look into.

I'd probably try to minimize the length of the exhaust hose, because the hose itself acts as a sort of radiator, emitting heat back into the room. I'd also consider drilling through a wall to send the drip line directly outside if there was no easier method.

Regarding garage door screens, they can be fancy or cheap. This one is $40 but I'm sure it has to be manually moved out of the way when using the garage door:

https://www.amazon.com/Magnetic-202x90inch-Retractable-Fiberglass-16-9x7-55ft/dp/B09PG85MNW/ref=asc_df_B09PG85MNW?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80058318199473&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583657840839200&psc=1


Meanwhile this one basically IS a second layer of garage door, and it costs $1500:

https://www.walmart.com/ip/Lifestyle-Screens-Garage-Door-Screen-7-H-with-Standard-Screen-Material-All-Widths-and-All-Colors-16-Wx7-H-Sandstone/870087787?wmlspartner=wlpa&selectedSellerId=101007355&adid=22222222222278089346&wmlspartner=wmtlabs&wl0=e&wl1=s&wl2=c&wl3=75110501374199&wl4=pla-4578710047047006&wl5=&wl6=&wl7=&wl10=Walmart&wl11=Online&wl12=870087787_10001026725&wl14=garage%20door%20screen&veh=sem&msclkid=3ea0f351015f14098b4091aeb4a00157&gclid=3ea0f351015f14098b4091aeb4a00157&gclsrc=3p.ds

The benefit of either is if you are working with chemicals, paints, dust, etc. you get fresh air but not the bugs. I have a backyard workshop with a window AC unit, and I often find it's not worth it to turn on the unit because I'm done with the project by the time the building cools down! So maybe consider how you'll actually use the garage - as an air-conditioned man/woman-cave or as a place to refinish a dresser or maintenance the car every once in a while.

[jeromedawg]

If you're using the garage to park vehicles, it may be a lost cause to keep it comfortable because you're pulling probably 500-600 pounds of super-hot engine and exhaust metal, plus a thousand pounds of sun-baked auto body, in there every time you park. Additionally, I'd be reluctant to spend money on a mini-split, just to spend money on the electricity to run it, just to keep the car-hole cooler. That's like paying money for gasoline to burn, and then paying money for electricity to remove the heat from the burned gasoline!

That said, you'd like to have some tolerable workshop space. The cheapest way to accomplish this is a window AC unit that you only turn on during projects. A used model will suffice because it will only be used intermittently anyway. The upside is that such an AC could be bought for $50-100 used and popped in a window with no professional labor needed. The downside is if your garage lacks a window! In that event, I would work really hard to see if I could figure out how to route a hose for one of those floor-sitting AC's that utilize a window. E.g. could you route such a hose to an outdoor dryer-type vent through the roof gables or soffits? Otherwise, you could just hack a hole in a wall for the vent.

Lastly, if the main reason you don't use the workshop with the garage door open is bugs, maybe consider those garage-door-sized screens that are popular in Florida.

So right now, admittedly and unmustachianly, we can't park in the garage because it's full of stuff lol. I'm planning to better organize things though once we have our HVAC system changed (this involves a portion of ductwork being removed that is blocking otherwise 'precious vertical real estate'). Once we get to the point that we can park one or both cars in it, and if I did want to go into the garage to do any work etc, I would most likely pull at least one or maybe both cars out depending on what it is I plan to do. I would also try to avoid going out there after just having pulled a car in. I figure if it's something like where I want to work in the garage in the AM and the car has been sitting overnight and cooled down, it's probably not as big of a concern.
We are getting solar so there's that as far as the concerns with spending more on electricity (well, assuming we don't run it so much and so often that it pushes us outside of our solar generation capacity, which I would doubt).

In terms of the portable floor AC units (non-evaporative I presume?), I could route the exhaust hose up to the small vent I described earlier. I don't know if it's advisable to route an exhaust vent like this *upwards* however. And I would just have a drain hose exiting out by the garage door (although with this too I don't know if a long drain line is advisable). The concern is that the vent is approx 15-20' or so away from the garage door, so I'm not sure what's more important as far as placement is concerned - should the AC unit be positioned for a shorter exhaust hose length or for shorter drip/drain line length?)

As far as bugs, that would be a concern as we have mosquitoes around here (especially in warmer weather). I've never seen those garage door screens so that might be something interesting to look into.

I'd probably try to minimize the length of the exhaust hose, because the hose itself acts as a sort of radiator, emitting heat back into the room. I'd also consider drilling through a wall to send the drip line directly outside if there was no easier method.

Regarding garage door screens, they can be fancy or cheap. This one is $40 but I'm sure it has to be manually moved out of the way when using the garage door:

https://www.amazon.com/Magnetic-202x90inch-Retractable-Fiberglass-16-9x7-55ft/dp/B09PG85MNW/ref=asc_df_B09PG85MNW?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80058318199473&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583657840839200&psc=1


Meanwhile this one basically IS a second layer of garage door, and it costs $1500:

https://www.walmart.com/ip/Lifestyle-Screens-Garage-Door-Screen-7-H-with-Standard-Screen-Material-All-Widths-and-All-Colors-16-Wx7-H-Sandstone/870087787?wmlspartner=wlpa&selectedSellerId=101007355&adid=22222222222278089346&wmlspartner=wmtlabs&wl0=e&wl1=s&wl2=c&wl3=75110501374199&wl4=pla-4578710047047006&wl5=&wl6=&wl7=&wl10=Walmart&wl11=Online&wl12=870087787_10001026725&wl14=garage%20door%20screen&veh=sem&msclkid=3ea0f351015f14098b4091aeb4a00157&gclid=3ea0f351015f14098b4091aeb4a00157&gclsrc=3p.ds

The benefit of either is if you are working with chemicals, paints, dust, etc. you get fresh air but not the bugs. I have a backyard workshop with a window AC unit, and I often find it's not worth it to turn on the unit because I'm done with the project by the time the building cools down! So maybe consider how you'll actually use the garage - as an air-conditioned man/woman-cave or as a place to refinish a dresser or maintenance the car every once in a while.

Wow, I had no idea those screens existed! The latter one you linked looks fancy but yikes at that price! With the first/magnetic one you linked, how do you move it out of the way when you want to pull the car in/out?

In terms of how we would use the garage, it would probably be more for when I am doing home projects/fixing stuff (that doesn't involve fumes - anything involving fumes, I would just do in our driveway or backyard) as well as for cleaning guns and organizing or servicing my fishing gear. I would even want to work out inside, eventually. So it's kind of a mixed use case. I wonder if it would make sense to just add an exhaust fan in the vent + ceiling fan (or perhaps an elevated box fan) and or just have another hole cut (and vent installed) across on the opposite side of the garage and add an 'intake' fan there? If I wanted to get fancy, I could create covers for them to close-off and then I could run an AC unit... this way the cold air doesn't escape. As far as insulation, I'm actually not sure if there is insulation in the ceiling above the garage and below the bedroom floors. I'll need to get up on a ladder and see if I can peek through a hole (not sure why the hole is there lol) that I noticed up there.

[Paper Chaser]

- If there's no insulation, add it. With your low humidity climate, I'd probably choose unfaced fiberglass, rockwool (or blown cellulose if the walls have sheetrock).
- Keep the garage space completely separate from the living space. There should be no ductwork shared between the spaces. As mentioned, this is not only to avoid fumes entering your living space, but also for fire safety.
- Shade the windows to avoid solar gain in hot months either externally with plants or awnings or with blinds internally. Special reflective tints can be found for little money and might help too.
- A window AC would be the cheapest up front, but is going to be less efficient to operate than a mini split, and may not be the most aesthetically pleasing option. They're also much noisier while running than a mini split.