AC Options/ Outside vents

[LADyver]

This is my first post, so I apologize in advance since I know the questions I'm going to ask are already somewhere in another post....but since we're pulling the trigger on a huge garage project on Wednesday, time is lacking to do the research on the AC. Here's the situation on a 3 car garage in So Cal:
We just gutted it. All electrical and plumbing are being put into the walls so we can insulate and drywall everything. We have a huge area (trussed) above the ceiling joists, so we're putting down plywood for a new storage area and creating an insulated ceiling in the garage. This should be enough to keep the garage tolerable even in the hottest weather, but having AC available in the garage would be nice, just in case our expectations fall short. We currently have three suicide vents and one larger 24" x 30" vent all on the east wall of the garage...the cabinet guy wanted to cover them all, but we're not sure if that's a good plan or not (there's no code saying we have to keep them open). Is it better to leave the vents open or seal them up? We park 1 VW TDI in the garage. For AC, between the portable dual hose AC units, the in-wall AC units, and the mini splits, which are generally used in what situation and why? Which ones recirculate the air, which ones bring in fresh air, and does it matter? If we choose to seal the vents would that affect the choice? Any basic information that you could throw at me would be greatly appreciated!! Thanks!

Sonja

 

[pseudorealityx]

They all recirculate air.

The Mini-split would be the 'best' application IMO.
The in-wall/window type unit would be 2nd best.
The portable dual hose types are good if you want to waste electricity and "sorta" get colder air.

 

[Milton Shaw]

All of the ptac (hotel/motel) in the wall units have some venting function. They can vent something like %10 to %20 of the air. None of the mini split vent at all as they only have a 3" hole for pipes/wiring to go through. The window units also usually have some vent function. You would need to have exhaust type fans to vent garage if you were running engines etc in the shop. The portable cool units don't really cool anywhere except right next to the hose blowing air. Ptac units would be the cheapest option and sometimes are even available used when motels remodel.

 

[pseudorealityx]

All of the ptac (hotel/motel) in the wall units have some venting function. They can vent something like %10 to %20 of the air. None of the mini split vent at all as they only have a 3" hole for pipes/wiring to go through. The window units also usually have some vent function. You would need to have exhaust type fans to vent garage if you were running engines etc in the shop. The portable cool units don't really cool anywhere except right next to the hose blowing air. Ptac units would be the cheapest option and sometimes are even available used when motels remodel.

Ceiling cassettes and ducted mini-splits have a 4" tap for a ventilation duct. It's only the wall mounts that don't have the option.


The issue is that none of these options are good enough to 'exhaust' a garage if you want to run engines. The ~50 cfm that you'll get out of these small vents isn't enough to offset the exhaust.

 

[LADyver]

Thanks for clearing things up in a hurry for me...we're signing the contractors today so we have from now until when they start to make any changes to support an AC system. The good news.....the only engine in the garage is my VW diesel and I usually roll in, shut off, and close the garage door behind me. The garage will not be a shop set-up, it'll be mostly for storage and light easy projects (and basically a huge playroom for the dogs while we're at work with indoor/outdoor access). We've decided that it's best not to block the vents, but would keep the option to open and close them. The garage houses a ton of 1" gas line for the tankless water heater that's there and we've been told that while blocking the vents shouldn't be an issue, it's wiser to keep them open.

I saw the ceiling splits and was curious about them but couldn't wrap my brain around it. What would be required above it? Since we're creating a ceiling anyway, I wasn't sure how involved it would be or if it would be less involved than the wall mount mini split.

 

[pseudorealityx]

Required above ceiling? Typically about 12" clear for the innards of the unit. Refrigerant connections are similar to any other. Condensate can be easy or challenging, but it depends on your exact installation.