If you wish to air condition the space you need some kind of insulated wall. Nothing is cheaper or easier than wood studs, drywall and fiberglass insulation.

Thanks mightyanvil, that's extremely helpful.

PS, mightyanville (or anyone) -- do you think just putting fiberglass insulation (with a protective covering) on the garage door will suffice to keep the cool air in at that point? The door is not insulated -- just thin metal painted a dark color on the outside, and when the sun hits it, it's like a heat radiator into the garage, seriously. Now I'm wondering if we should do more than insulation... ??

Will you need to be able to open the garage door?

Sounds like you would need a hefty AC for vertical blinds to contain the area well enough to cool, especially for occasional "on/off" AC use.

If you can do without ever using the single door, you might build two walls, the partition and also a wall in front of the garage door - then insulate everything.

If you do want to try just a non-insulated partition curtain or whatever, think about closing the gaps above with a sheet of plastic or something. Still, the radiant inferno from the garage door is going to make this tough - I'd be inclined to shoe-horn in an old 15,000 btu AC somewhere and it might be enough for the rapid cooling you need.

Thinking further, maybe 8,000-10,000 btw would do it for one uninsulated garage.

What I've done in the past is to frame a partition wall with a walkthrough door between the small and large garage doors. Then about 4' back from the small garage door,(far enough back to be able to open the small garage door), another partition wall parallel to the small garage door. Insulate and sheetrock. This allows you to open the small door and use that area for garden tools, bbq storage, etc. You will want to have an egress window in the exterior wall as an avenue for escape/emergencies in the partioned off room.

Thank you everybody. I think we need to retain the option of opening our garage door. Plus the equipment extends almost to the garage door. DH bought commercial treadmill, bicycle, and huge universal gym from our old country club when they got new equipment.

Homebound, what do you mean by an old 15,000 (or 8,000-10,000) BTU AC?

We had an AC company over and they recommended an individual freestanding unit, don't know its name. The cooling unit sits outside next to our normal AC, and is piped into the garage to a thing that hangs up high on the wall (but doesn't go through the wall like the old wall ACs). It has a thermostat and all. Apparently they use a lot of these in Mexico! Then Sears came along to give a second bid, and the Sears guy said that this wouldn't work because it would get it too cold, then would freeze up, and not cool any more. This was going to cost about $4K, so we weren't about to mess with something that might not work.

That's when we decided on a couple rolling ACs.

What do you all think?

I think you should go to your local outlet store and pick up a 15K unit or perhaps a couple of 10s...by me stores get them reconditioned each year, usually $200 or so...assuming you have garage windows to put them in. See how it works.

We had one of the A/C that your first person recommended in our converted garage to playroom - yes they use them in many parts of Mexico and south america and that thing was great - also worked as a heater if you ever get any colder days.

THe free-standing ones that Sears sells IMHO suck. Ask the salesman how many of those units they get on return - the number is ridiculously high. They simply don't work well - the ventilation set up for them is a work around versus a part of the design of a functioning unit. It is far from efficient.

IF you cannot use the old fashioned window units - the cheaper way to get efficient cooling - then go with the first unit. We never had any problems with ours at all.

You will be unhappy with the free-standing - we borrowed one - the owners were happy to give it to us ;-) while renting a cottage during our remodel. It was the top of the line for the free-standing units and barely cooled a 300 sq foot room running full blast. I can't imagine even 2 being able to adequately cool a garage space - especially for working out.

Example, a 5000 BTU is a "one room AC" (not very powerful, that usually cools slowly), and 8,000 can do more powerful, quicker cooling, etc...a 15,000 would probably chill down the entire garage enough for your use even without insulating for the time you work out.

Anyway, here's another alternative. Frame the room (two walls), so that one wall still allows garage door to be opened. Insulate. Put a sleeve for an AC right into the wall (so that the "outside" of the AC vents into the hot side of the garage) - catch the AC condensate in 5 gallon bucket).

This is how we cooled the office part of an office + warehouse combo. Just had to dump the bucket every few days.

And while you're at it, if you might need some heat you could install an electric baseboard.

....rather see them use a window then dumping the hot ac exhaust into the already hot garage...but you gotta do what you can do.

Question...do you plan to run these round the closk or are you looking for a quick cool down maybe a half hour before you exercise....just consider how long it may take to cool that portion of the garage if not running round the clock...whic may end up costing you $$$$....

Sure, window is better. But for occasional use and the "appearance factor" of a traditional AC in the window, it's an option, esp. for a larger old (cheap) unit that cools quickly.

Still, maybe a free-standing unit as originally mentioned would suffice.

The garage windows face front and it's a very pretty part of the house, and the side where it could be put through the wall is totally visible as part of our front yard, so we can't have a window or wall AC. Not sure that's even allowed in this association.

Homebound, your idea is brilliant, thank you so much, that never occurred to us. We will either do that, or spring for the big $4000 unit that gldnfan endorsed.

Gldnfan thank you for that info. Also, I wondered about those rolly ACs in the situation.

Thanks all for your ideas, now we know we will build a real wall with a real door, and we have our two selections of AC to choose from.

Will get back and let you know what we do and how it goes. Probably sooner than I think since DH wants to try to build the wall ourselves.

Just google "wall framing basics" or "wall framing" and pick through sites

Here is a link that might be useful: wall framing basics

Wow, great site, thanks sierra.

homebound, our last posts crossed in cyberspace. Maybe we will just see how the little rolly thing works prior to doing anything else. For now the big adventure is the wall.

too bad about the window location. I'd then opt for putting the unit(s) in the wall into the garage I guess...if you can live with the added heat and noise. If you build the walls, a wall unit should cool it no problem and 2 walls plus a wall unit will never come near $4k....that seems absurd unless you are planning on staying there for quite some time...and if such is the case, maybe you want to finish off that room with the two walls and look into cooling / heating that new room with your current heating / cooling system....I bet baseboard will cost you a fortune if temps get low where you live....good luck!

The Ductless wall mounted A/C unit was discussed on another forum with a link I will try to post here - I am new to the forum and not sure if I will be able to do it successfully ;-)

The other nice feature is that they are high on the wall directing the air where it is most needed while working out since it is our upper body that needs cooling down. Cool air is always better coming from the top down.

Here is a link that might be useful: A/C Units

In case anyone is interested, we ended up having a wall built with a door of course and electric in the wall, and a wall AC unit through the wall venting into the larger part of the garage. The hose drips into a pail, which I know is kinda unprofessional but it works. DH slipped thin styrofoam panels into the panels of the garage door, and that does a good job of insulating (since our garage door is made of thin metal which could no doubt be opened with a handheld can opener!)

Bottom line is that it works great, cools great, looks good, and DH is thrilled to have his own gym. I don't even notice the AC sticking into the garage any more, as it's way up at the front.

Thanks to you all for helping me figure out what to do.