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Thread: Using a window unit to cool shop?

  1. #1
    Join Date
    Mar 2014
    Location
    Houston, TX
    Posts
    437

    Using a window unit to cool shop?

    My 1500 sq ft shop has a 8000 btu window unit in it to cool a small office room. 8x15ft. Anyways, Today for the heck of it I decided to see if it would cool the whole building and I swear after it was running for about 15 minutes the shop was a few degrees cooler! Lol I actually had a fan on to blow the cool air from the office room outside to the rest of the shop. Makes me wonder if I just got a bigger 240v unit if it would cool the shop. It was only 85 degrees outside today, so maybe that was the reason it seemed like it was working. I never messed with the window a.c. unit before since I thought it would only be big enough to cool that little room.

  2. #2
    Join Date
    Nov 2012
    Location
    North Dana, Masachusetts
    Posts
    486
    I use a 120 volt window unit for my 1200 sf shop.I also have 10" of insulation in the walls, 14" in the ceiling, a well vented attic, and shade trees on the east, south, and west. The reduction in humidity is great. When it gets really hot, I add another window unit. I didn't need it last summer.

    I also have a dust collector with no return air, it dumps in a trailer.

  3. #3
    Join Date
    Apr 2017
    Location
    Tucson, Arizona
    Posts
    1,204
    I've got two Gree 3 ton heat/cool mini-spits installed into my 1000 sq. ft. machine shop, one at each end. I started out with a single 3 ton unit at one end, but it was not sufficient to heat/cool the other end of the room. Walls are 6 inch thick with fiberglass insulation, double pain windows, and foam insulation on the roof. I have barely used them this summer, because with the lack of rain and accompanying humidity, the evap. cooler worked great. I will definitely be using them for heat this winter. I live in Arizona where it can get pretty warm in the summers.
    David

  4. #4
    Join Date
    Apr 2013
    Location
    Black Oak Ark.
    Posts
    254
    Get a mini split . A window unit will help, but in Texas , I'd do it right .

  5. #5
    In the past, I've cooled ~900 sq ft in N. Texas with a 240V window unit. I've forgotten the exact size, but it followed typical BTU/sq-ft guide lines - and was fairly well insulated space, with 2ea. 8' garage doors. Guide lines say you need 24000 to 30000 BTU unit for 1500 sqft, and I might go on the high end - - having been to Houston in summer.

    My current research leads me to believe I can do 'expensive' mini-split and get much better efficiency long-term, or window unit for about 1/4 to 1/3 the upfront cost. Analysis paralysis reigns for the moment.

    Houston and the high humi... I mean viscosity you suffer from may skew this a bit. Have you considered moving your shop into a frozen food storage warehouse? Or, just work in a swimming pool?
    Last edited by Malcolm McLeod; 10-19-2020 at 10:12 AM.

  6. #6
    How about a two-zone mini split? You can get them with different BTU ratings for each blower; for example this model has a 24kBTU outdoor unit with 7k and 15k BTU blowers. This would let you keep the two spaces at different temperatures.

  7. #7
    I haven't done it yet but next summer I will probably get a 5,000 btu window unit to cool my 340 Ft2 shop garage. It is insulated well. I had to move a gate and put in a doggie door for my dog but that part is done. I also want the little window unit for potential use if a hurricane knocks out our electricity for awhile. I am willing to buy a generator big enough to run the refrigerator, entertainment, and a little window unit to cool one room but the infrequency of power loss where I live doesn't justify to me a big unit that would power the house. Anyway, the idea is to normally use a little unit to cool the shop in the bad part of the summer and move it to a window in the great room in an emergency.

    My son used a 5,000 btu window unit to cool his small house for a couple months when his central AC went out before he got it fixed. It did not really cool the house but it kept one room pretty cool and he could use the other rooms even though they were hotter than he wanted. This is what I think I would have if I did it in an emergency. One decent room and a lack of comfort in the other parts of the house. Livable for a short time period.

  8. #8
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
    Posts
    9,889
    Be honest. if the power is out that long you are not going to want to go to the work of dismounting, carefully, the old unit and figuring out how to mount it without taking off all the mounting brackets. You are just going to buy a new one because it is too hot to screw around for hours.
    Bill D

  9. #9
    Join Date
    Jul 2003
    Location
    Winterville, NC (eastern NC)
    Posts
    2,360
    Been cooling my 16 X 32 shop for years with a 120 volt window AC unit. Insulation in the walls and ceiling makes a great improvement. I have a humidity gauge inside and the running unit clearly lowers the inside humidity.

  10. #10
    Join Date
    Jan 2010
    Location
    Yorkville,IL
    Posts
    265
    I have 22,000 BTU wall unit in my 1,500 sf shop. It works great in 95 degrees humid Midwest summer.
    Jaromir

  11. #11
    Join Date
    Jul 2007
    Location
    Yorktown, VA
    Posts
    422
    I have a single 24000 BTU window unit for my 1200 SF shop that is fully insulated and even on the hottest days it does not run continuously. I normally leave it in energy savings mode and it keeps the shop at 70 degrees F even it when it's over 100 degrees outside. I have R-13 in the walls and R-38 at the roof.

  12. #12
    I have an 18,000 BTU window unit in west Texas. It cools ok but have to use fans to keep the temp uniform throughout. Typical 2 car garage. Since it’s cooled off, it doesn’t run often enough to keep the humidity down. It’s often more comfortable outside than inside when I get home. I wonder if a dehumidifier would help. It’s not the best setup, but for $400 it’s GREAT!

  13. #13
    Join Date
    Mar 2003
    Location
    Upland CA
    Posts
    5,548
    1600 sq. ft. shop, insulated and drywall. Live in SoCal, and my 24000 BTU window unit in the middle of the long wall works well on 100 plus days. It will cycle on the hottest days.. I use two oscillating fans to move the air around also. I also leave a window open about a foot on the shady side of the shop all year, so the DC will not starve.

    Not much humidity to worry about here.
    Rick Potter

    DIY journeyman,
    FWW wannabe.
    AKA Village Idiot.

  14. #14
    I know that I have posted this before but I will post it again for the op in this thread. I purchased a used 5 ton HVAC system for my shop which is roughly 90ft x 80ft not including the office or paint room areas. My shop is old but was built out of red iron in the 1960’s I believe. It was insulated at some point with the roll insulation that is common in metal buildings. My insulation is not in good shape and a lot of it needs replaced. My 5 ton a/c unit cools most of my shop very well. I did recently purchase another 5 ton unit to put at the other end of my shop which should help a lot next summer. I am having a buddy that does spray foam insulation do a 12” strip where the walls meet the ceiling and another 12” strip at the bottom where the walls meet the floor which should seal my shop up and make it substantially easier to cool.

  15. #15
    Join Date
    Feb 2007
    Location
    southeast Michigan
    Posts
    676
    I have a 30x30 foot space walled off in my pole barn for my workshop. The walls have 6 inches of insulation and the 12 foot ceiling has at least a foot. It generally stays comfortable on hot days but if we get enough of them in a short period the temp inside starts getting less comfortable to work in. That's what was happening here in SE Michigan this summer.

    So I finally decided to buy a window A/C unit. I have no windows so I installed it about the middle of a side wall. It's a 22,000 BTU, 220 volt unit and it works great. Does not come on anywhere near as much as I anticipated and it's very quite. Then came the days when the temps were down but the humidity levels were up. Fortunately, this unit has a "dry" mode in which the compressor and fan (only in low) runs but not constantly. I would say this is one of the best "tool" purchases I've made for my shop. Wish I would have done it sooner.

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