A/C Strong enough for a 500 sq/ft Garage


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I have a ~21 x 23 (483 sq/ft.) garage workshop. It has an 8 ft. ceiling that, believe it or not is insulated. The walls are simply cinder-block that I am currently painting. I thought about trying to put in studs and insulate the walls etc. but that would cost way more than my modest paycheck could cover. If I were an all-day/er’day cabinet maker, carpenter, woodworker... I could justify it. But I’m in the shop 2-3 days a week. 

I live in Charleston South Carolina... so I’m just a couple of months, it is about to get to be too hot to even breathe in my garage, much less tackle projects for hours. I’ve seen those Mitsubishi air conditioners that have a unit outside and a vent that is installed through the wall inside. But those cost thousands or dollars. Do any of you guys know of any new technology that I am missing that can cool a 500 ft/2 space?

To make it more interesting, I’d like to host small art events in my shop as well. So, I’m not just looking for... “It’s 98 outside and 85 in the garage.” I’m looking to cool the place to 74-75 degrees. At least that is the END goal. I’d be fire w/ 80 degrees until I can save enough to do a more serious insulation job. 

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We have a 440 sq. ft. two car garage that is our dedicated shop (my wife doesn't mind parking outside).  The shop is full insulated, including the door to R-13, and we put in a one ton (12,000 Btu) Gree mini-split ductless unit Oct. 2013.  It is a high efficiency unit (22 SEER, I believe) and was about $2,300 for turnkey installation.  I could have bought the unit for about $1,700 and done the install but I learned that the 7-year warranty would be null and void if I installed it myself.  So I paid the extra and had it installed.  We paid $500 to have insulation blown in two walls and the ceiling and I insulated the garage door.  The common wall for the house was already insulated.  The garage is on the west side of the house so it catches the full brunt of the summer sun and yet still stays comfortable even when it's 105° outside.  The other day it was 9° outside but 70° in the shop.

The unit is so efficient that our electric bill has never changed even though the unit is on 24/7.  It stays very comfortable year round and has been well worth the initial cost.  Nothing sweats or rusts in the shop, wood is always at a low MC, and the woodworker (ME) really likes the climate controlled environment.  I think the reason our electric bill never changed is because the door into the house stays open unless I'm really stirring up some dust and my guess is the mini-split takes some of the load off the main HVAC unit for the house.

David

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My dust remedy is to open the back door and turn a big fan on high blowing outward. I would enjoy summer AC here in hot humid florida. But I think the AC   would choke up real fast with all the flying dust. It may also violate the warranty.

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A year and a half ago, my dear wife insisted, after seeing me with a sweat rag around my head, that I buy a a/c unit. I bought the highest btu window unit available that HD had, a/c and heat. It keeps my shop/garage, 24x32, very comfortable, year round. 

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Good question about dust collection - no matter what your solution will be, you should plan on periodic maintenance/cleaning to make sure it doesn't get chocked with dust.

The mini-split systems are supposed to be extremely efficient - yes, a little more expensive up front than window units but much better on the electricity bill.  If that's not in the budget, there's no reason a properly sized window unit couldn't do the job but you want to size it right so it keeps it cool and controls the humidity.  If you don't have any windows, the concrete block construction might complicate installation. You also want to do your best to seal and insulate the garage doors, especially if they get any of the hot sun - they'll act like radiators heating the garage unless they're insulated.

To your question about "new technology" ... mini splits seem to be the best advancement these days.  There's no magic though, you have to pay for what you get.  There are some systems that are self-installed, so you might look into those to save a few bucks.  

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Most of the dust and chips are captured at the source so there's rarely any airborne dust in the shop.  After I got the HF 2 HP DC there seemed to be more dust than usual and it was because the standard 5 micron bag keeps everything around it coated in a very fine dusty powder and that gets airborne quickly.  So I used to clean the filters every week or so and then I got the Wynn 0.5 micron filter.  Now there's no fine powder anywhere and I clean the filters every 3-4 weeks on the mini-split.  Twice each year, maybe three times, I blow out the condensate drain and clean everything I can with compressed air.  When I spray lacquer I turn the unit off so that overspray doesn't get into the unit.  It would be dry by the time it hit the mini-split but I'm just being cautious.

David

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I just bought and am getting ready to install a mini split (which is what I think you were referring to).  It's this unit here: https://www.pioneerminisplit.com/collections/wys/products/pioneer-18-000-btu-20-8-seer-230v-ductless-mini-split-air-conditioner-heat-pump-system-full-set  I live in Kansas so I needed equal parts heating which is why I went with the inverter++ model which can heat till the outside air is -13.  I am guessing you wouldn't need that for South Carolina but it does get cold enough there where you'd get use out of the heat setting.

Like you, I wasnt wanting to spends thousands of dollars and heating and cooling.  I roughed it this past summer with just fans and that's not going to work this summer.  I had crappy little space heaters this winter but they stop getting the job done once it drops below 40.  I figured I'd invest in a good heater now and solve the cooling problems once summer arrived.  Once I started looking into how much a nice heater was going to cost I was around $400-500.  I wasn't sure what a/c would cost but I guessed at least that for a decent unit.  I also wanted the shop climatized 24/7.  

By that time it made sense to start investigating mini splits.  I read a ton of reviews and it came down to 3; Pioneer, Blue Ridge, and Mr Cool DIY.  The Mr Cool DIY is a good unit and you dont need an hvac tech to install any of it.  However, depending on your install you're going to end up with extra line set that will look pretty tacky just laying around.  The Blue Ridge model couldn't handle the extreme cold so I went with Pioneer.  With required accessories (wall bracket, line set cover, electrical), I am in it for about $1250.  I am doing 90% of the install myself and have an hvac that will do final connections and vacuum the system for $100-200.  So all in hopefully less than $1500.  Yes, that is more than buying separate units but this gives me one unit that is extremely efficient while using very little of my precious shop space.

In regards to the dust, I read a lot of reviews of mini splits from guys that have them in their shop and I didn't come across a single problem.  You just have to be vigilant with cleaning the filters.  Now, that's anecdotal as I am sure there are plenty of people that have had problems but it's possible they didnt take care of their units.

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  • 1 year later...

I have been using this supplier, www.thermospace.com

Nice selection and free delivery, I have purchased and installed 3 units in 3 years. ( all new installs not replacements) am on my 3 year with a 24000 btu Air Con unit. if you take a close look at the pricing a 24000 is almost cheaper than a 18000. I currently just installed a 24000 btu in a 30x50 pole barn with min insulation (r-3) and open rafters. it was 103 degrees here last week and barn didn't get over 80 degrees with very low humidity. In addition, I advice to look here for the wall mounted option.

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