Shop AC

bss1

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H-M Supporter Gold Member
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I have an un-insulated 640 SF garage/shop. It has open stud walls and rafters. The walls are currently clad with Peg Board.

I am considering installing a window or through wall AC with supplemental heat to provide temporary cooling and heat while I am in the shop and working. I don't expect it to feel like my living room out there. It gets up in the high 90's for about 3 months and even with doors and windows open and fans running, its not a real pleasant place be. I am just looking for some cool air blowing on me, maybe supplemented with some fans to move the temperature 10 to maybe 20 degrees to create a more comfortable working environment. The heat would only be used intermittently during a few cold winter days to keep the temp in the shop above freezing, and to knock the cold edge off when working after a cold front. 6 months of the year I won't need anything but open doors. This wouldn't be for 24/7 climate control, just mostly used during the time I am out there in the evenings or on weekends, during the few months when it is needed.

I know that it would be better to insulate, but I have future plans to renovate and will address that at that time. I am just looking for an interim solution for cool air. It is too humid here to use the evaporative type of coolers and I don't like the thought of all that additional moisture in the air.

I am looking at the window units sold at HD and LOWES. They both have a similar selection. I am limited in power for this effort to either 20 amp 115V circuit or a 20 amp 230V circuit. There looks like Lowes/HD have a 230V 18,000 BTU unit that draws 7.3 amps cooling and 16 amps heating. This unit is rated for a 1050 sf area.

18000 BTU unit is more than what is needed for this footprint, but given the lack of insulation and open rafters, I am thinking the larger unit may be a better choice. Otherwise, I think it may size to a 12 to 14 ton unit.

I am wondering if anyone has done anything similar and if this worth pursuing. I can accept an increase in the electric bill and don't mind the +/- $500 investment in the unit.

Thanks for your help

Edited to change tons to BTU's!

Brad
 
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Something is not right with some numbers. 18 tons is a HUGE amount of refrigeration.

1 Ton of refrigeration = 12,000 BTU/hr

My central heat pump is a 4 ton capacity.

Consider a portable A/C unit. This style has a flexible duct to vent the warm exhaust air to an outside window. With this style you can move the unit closer to where you are working. You may feel cooler even if the overall room is warmer.
 
It wont be 18 tons. There are 12,000 BTU per ton of refrigeration. You may be looking at a 18,000 BTU unit. Always go 220/240 when you can. Down there, your main objective it to remove the humidity, so expect it to run quite a bit and make lots of water, which is a good thing. And if any way possible, get some sort of insulation in the ceiling. Even if it's temporary.
 
I'm sorry I meant BTU's!
 
I have a 20x24 (480 sq.ft.) shop. It has open rafters but is insulated all around. I have a small 110V window (thru the wall) AC and a small ("garage" size) 220V electric heater with a fan. Both work nicely and will keep the shop more than comfortable on 0 degree to 100+ degree days if I give them an hour or so to get started catching up.
I can go out and look at the exact size ratings if anyone wants to know. If not it's nap time!
 
As stated above, I don't think your really looking at 18 tons, not with that low power draw. Sounds more like 1.8 tons. Anyway, for what little fiberglass insulation costs, I would at least insulate the roof. Won't take long if it's all open as you describe.


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Look into "mini split" type air conditioner/heat pumps. They are like a small version of a central air conditioning/heat pump system. The compressor unit installs outside, only the two hoses need to go through the wall, and then there is a small evaporator unit inside, up on a wall. It is quiet, unobtrusive, and good ones are even more efficient than a whole house heat pump/air conditioner combo per BTU delivered or removed. They are not all that expensive, and not that hard to install (pre-charged system and hoses.)
Here is just one vendor, there are lots more... https://www.ecomfort.com/cooling/mini-split-heat-pump-systems.html?utm_source=bing&utm_medium=cpc&utm_campaign=Style - Mini Split&utm_term=mini split heat pump&utm_content=Mini Split Heat Pumps

Edit: Insulation and other energy saving changes always come before just wasting electricity or other energy. You cannot heat or cool the outdoors very well or very cheaply.
 
Mine is 30x40 with high vented ceilings, insulated all around, two windows per wall, and insulated garage doors on both ends and one side. Got fans, a portable AC unit, and a rollaround swamp cooler. The shop is about 20x30. I sometimes use the AC with assist from a floor fan, but the PortaCool swamp cooler does a pretty good job, too. Only problem is that it goes through a lot of water.
 
BSS1
I have a 30x30 insulated metal building machine shop area here in east Texas. I have a 3 ton central air system I use (free) when needed and it is wonderful. But I also have a stand alone dehumidifier I run all of the time set to 45% humidity. That is what really makes the difference in comfort and saves the machines and tooling from surface rust.
 
I have been looking at one of those portable units that you run the hose out a hole or a window. I do not have much Electric to spare, so looking at that. One thing I know from being in SA, is Humidity is the killer, I'm from the Tx Panhandle and 100 with low humidity is a lot more bearable than the hi 80s down here. and the few times I have been in the Houston area it was worse there. So I see where the Swamp cooler is out to start with, but need something that will pull humidity if possible. If possible even just plastic sheeting on ceiling to help seal it up would help when you put AC in there. Just my 2 cents. Hope it helps.
 
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