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Forum topic by newwoodbutcher posted 03-17-2016 09:35 PM 943 views 0 times favorited 19 replies Add to Favorites Watch
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newwoodbutcher

552 posts in 2318 days


03-17-2016 09:35 PM

I live in north San Diegi county. My two car garage is my shop. It’s not airconditioned. It gets really hot here in the summertime. I have no windows where I could use a window ac unit nor do I have any walls I could cut out space for a window unit. What are my options? I could run a vent line up through the attic. Anyone got a solution?

-- Ken


19 replies so far

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onoitsmatt

227 posts in 644 days


#1 posted 03-17-2016 09:44 PM

I’m in Phoenix and have the same issue. Likely much worse :). My garage is cinder block, so would have to do pretty major work to get a window unit in. I looked at getting a split system which would only require a fairly small hole to be drilled though the wall, but it is quite expensive (low end would run near $2k just for the unit if you can install it yourself). I opted for an evaporative cooler (Mastercool) which probably wouldn’t do you much good in San Diego with your humidity. It doesn’t do me any good after late June/early July through late September.

I also vented the overhead doors and we have a service door out the side that I also vented to get a little air moving. It didn’t make a noticeable difference though.

There’s always fans. Lots and lots of fans.

-- Matt - Phoenix, AZ

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conifur

955 posts in 619 days


#2 posted 03-17-2016 09:47 PM

One of those free standing that duct out like a clothes drier, or an attic mount possibly, or those that mount on the wall and the condenser is out side on a pad that Mitsubishi makes.

-- Knowledge and experience equals Wisdom, Michael Frankowski

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clin

514 posts in 464 days


#3 posted 03-17-2016 10:45 PM

I’d look into a “mini-split”. As mentioned, these just require a small hole (3” dia.). They are a refrigerated system with a unit outside and a unit inside connected by two refrigerant lines and a power line.

Note: The inside unit still needs a drain line for condensation. This can be run outside or into a drain. Not complex, but it needs to be there.

Outside unit can be on the ground or up on the roof or any place else you want to put it. It will need 240 Vac. Typical inside unit is mounted high up on the wall.

This is almost certainly the easiest (though not necessarily least expensive) due to ZERO duct work. I had one put in for my shop and a few other rooms. I did a lot of research, seriously thought about installing it myself, but it takes just enough special tooling and expertise that I decided it wasn’t worth the risk of screwing it up and then paying someone to fix my mistakes and redo it.

These things are super efficient, but you are looking at >$3K (maybe a lot more) installed. They also are intended to run 24/7. You can certainly turn them off if you are not going to be in the space for days at a time. But don’t expect it to take a 120 deg garage and drop it to 75 in 15 minutes.

They cool very gently, no blast of cold air. Even in a quiet room it can be hard to tell when they are running. They don’t cycle on and off like a typical AC. They have a variable speed compressor so they throttle up and down. It’s one reason they are so efficient.

Another issue is shop dust. These recirculate the air and shop dust can collect in it. I simply make a point to keep mine off when kicking up dust. But also, I have a Jet room filter and it exhaust towards the mini-split, so if the room filter is on, it’s filtered air going towards the mini-split.

Well respected brands are Mitsubishi and Fujitsu (what I have). There are other good brands, but you won’t go wrong with either of these two. I heard bad things about LG customer service (hard to get parts).

I would also go with evaporate air, except as mentioned it is too humid in SD. The nice thing about a swap cooler is you are constantly drawing in outside air. It is a great way to keep dust out of the shop air.

One other comment. Do you really need AC? I thought the summers were pretty mild there. I’m thinking maybe just some good ventilation to bring in cooler outside air. Of course you need some way to do this, and your walls are out, so maybe from overhead.

-- Clin

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hotbyte

844 posts in 2443 days


#4 posted 03-17-2016 11:23 PM

At work, We’ve used free standing A/C units in network rooms that didn’t have adequate HVAC to keep cool with equipment running. Exhaust was vented into ceiling and a pump rigged up to empty container that captured condensation.

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Holbs

1383 posts in 1497 days


#5 posted 03-18-2016 01:00 AM

what about cutting a hole in your man door, if you have one? Tis what I did, knowing that I will eventually put a window in the door anyways.

-- Yes, my profile picture is of a Carpenter Bee! The name is derived from the Ancient Greek "wood-cutter"

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MadMark

978 posts in 921 days


#6 posted 03-18-2016 02:46 AM

Here in Florida I have an oscillating pedistal fan & work after sundown. Garages are not sealed for AC and are notoriously air leaky. There are insulation kits for your alum garage door at your local home center. You should be working in short sleeves anyway. LOL

When it’s really hot I work in short sprints with lots of cold fluids and dive for AC often.

Plus there is the DC issue, you can’t vent and have AC – pick one.

M

-- Madmark - Madmark2150@yahoo.com Wiretreefarm.com

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jonmakesthings

68 posts in 286 days


#7 posted 03-18-2016 04:34 AM

I agree, a mini split would probably be your best option if you want actual AC. They’re extremely quiet and efficient. But they do require a bit of work and working with freon so I wouldn’t recommend tackling it yourself, get a company to do it.

If you decide to do it, I definitely think you should insulate your garage, at least a little. Good insulation is the biggest money saver. Otherwise you might be running it and running it and never cooling down because they don’t put out much air at a time.

I do HVAC for my day job

-- How can you have any pudding if you don't eat your meat?

View Fred Hargis's profile

Fred Hargis

3950 posts in 1961 days


#8 posted 03-18-2016 11:19 AM



One of those free standing that duct out like a clothes drier, or an attic mount possibly, or those that mount on the wall and the condenser is out side on a pad that Mitsubishi makes.

- conifur

That may work (one of these) if you can get a smaller hole for the vent. I have the one that I linked and used it in my shop last summer. They need to be oversized (IMHO) compared to a window unit (I can get by with an 8K window unit, but the portable I have is 10K) I think that’s because they discharge room air through the vent, constantly drawing in out side air…in my case the shop wasn’t as cool. All in all, I don’t like them nearly as well as a window unit, but it may still be a possibility. One thing about them is they don’t stick out in the hot sun like a window unit does.

-- Our village hasn't lost it's idiot, he was elected to congress.

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TheGreatJon

296 posts in 701 days


#9 posted 03-18-2016 12:33 PM


They need to be oversized (IMHO) compared to a window unit

- Fred Hargis

Yes. I would say significantly oversized. I tried one last summer (Kul, I think) that was actually a tad undersized and it made zero difference in the shop conditions. I guess it could have been the particular model, or maybe I just got a lemon, but I was surprised how ineffective it was.

-- This is not the signature line you are looking for.

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ClammyBallz

309 posts in 604 days


#10 posted 03-18-2016 04:43 PM

Same issue here. I have two of the portable free standing AC units for my shop. I made a sliding board for the 4” vents that stretches across the garage door on the floor and locks into the track. I lift up the door then set the board in place and attach the vents. I cut a notch out in the track to lock the door in place.

View newwoodbutcher's profile

newwoodbutcher

552 posts in 2318 days


#11 posted 03-18-2016 05:57 PM

Thank you all. I have some research to do. At least now I have a direction to go.

-- Ken

View clin's profile

clin

514 posts in 464 days


#12 posted 03-18-2016 08:43 PM



That may work (one of these) if you can get a smaller hole for the vent. I have the one that I linked and used it in my shop last summer. They need to be oversized (IMHO) compared to a window unit (I can get by with an 8K window unit, but the portable I have is 10K) I think that s because they discharge room air through the vent, constantly drawing in out side air…in my case the shop wasn t as cool. All in all, I don t like them nearly as well as a window unit, but it may still be a possibility. One thing about them is they don t stick out in the hot sun like a window unit does.

- Fred Hargis

AC unit ratings are at one very specific set of conditions. While 10,000 BTU/hr should be plenty for a garage in SD area. You’d have to see the details on what it does at the conditions expected.

I also agree that the fact they are exhausting inside air, which means outside air has to be getting drawn in somewhere, is going to lower the total efficiency. Makes me wonder why they don’t just run two hoses to the window. Perhaps the loss isn’t that significant.

This also may be an example of the difference between what you need to keep it cool, versus what you need to cool an already hot space down to a comfortable temperature.

I did a quick calculation (I.E., maybe completely wrong) and a 10,000 BTU/hr would take something like >10 hours to cool a double car garage concrete slab about 20 F. Of course it’s not necessary to cool the slab completely to get the room cooler. But it’s also not as simple as just cooling the air, which would go much quicker. The hot walls, floor and contents of the space will radiate heat.

-- Clin

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newwoodbutcher

552 posts in 2318 days


#13 posted 03-19-2016 05:57 AM

Wow. Great conversation. Thank you all. I never heard of a mini split before, or even a split. I checked them out online, They look pretty cool but a bit more complicated than I would do on my own. I did an online calculation for my oversized double car garage/shop. Said I need a 12000-15000 btu unit. The attic over the shop is well insulated and has a radiant guard over all the underside of the roof. The walls are not insulated and the oversized window is a big box single pane aluminum 4footer. There are spots around my garage door that I can see through. Obviously I’ll have to seal that. My wife suggested punching a hole in the wall between my shop and the adjoining single car garage and hange a window unit between them. I could open the garage door in the single car spot to get the fresh air needed. Does that make any sense? it would be way less $$$$ than a split.

-- Ken

View onoitsmatt's profile

onoitsmatt

227 posts in 644 days


#14 posted 03-19-2016 01:50 PM

If your wife says it is a good idea, then it is. You’ll need to run a drain line for the condensate on a window unit. A garden hose out the door will do.

-- Matt - Phoenix, AZ

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hotbyte

844 posts in 2443 days


#15 posted 03-19-2016 02:18 PM

Sounds like a great solution!

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