Window AC, go oversize or .....?

[Whitworth]

Shop space is 1000 sq ft. with 8 ft ceilings. The question is if/when you installed a window AC unit in your shop, did you go oversize or spot on for sizing the unit?

The one I'm looking at is about $600, 220 volt, recommended for 1500 sq ft space. Didn't write down any other info.

1000 sq ft was about $100 cheaper. Typical big box merchandise.

I want it cold fast in the shop, and probably spend 2 to 4 hours a day in the shop during the summer months. Probably more if it were chilled️️

What is your experience and opinions?

 

[Davefr]

An oversized unit may not be effective at removing the humidity from the air due to short cycling.

Instead of guessing, run a load calc. for the space and match it up accurately. (ex: Manual J)

 

[Falcon67]

Sounds like you're comparing an 18K BTU (1000 sq/ft) vs a 24K BTU unit.

Going to depend a lot on the insulation and circulation. I have R13 walls and ceiling, ceiling panels are caulked to reduce air leakage, no vapor barriers or anything like that. I can keep the 672 sq/ft open area of the shop cool with a 10.5K BTU 120V window unit. It was left over from another house and I didn't care to buy a new one. Attic temps run 110~120F in the summer. I used an 8K in the 288 sq/ft tool room because the LG had a really good fan for moving the air vs the cheap underpowered Frigidaire units. An 8K is "over sized" for the 288 sq/ft, I don't have any issues with short cycling. If I use the 48" tall post fan for circulation, I just don't run the unit on high.

If you have good insulation and some circulatory fans, plus keep the doors closed the 18K may be plenty. In this climate - hot, dry - I'd buy the 24K.

 

[Milton Shaw]

Go oversize if you are just going to run it when you are working in there. A large unit will cool it fast. If you are going to run 24/7 then size the unit based on heat loads, otherwise the unit will not remove moisture properly. For my heater I sized it where I can turn it on and in 15 minutes temp will be at working temp.

 

[zmaxmotorsports]

Sounds like you're comparing an 18K BTU (1000 sq/ft) vs a 24K BTU unit.

Going to depend a lot on the insulation and circulation. I have R13 walls and ceiling, ceiling panels are caulked to reduce air leakage, no vapor barriers or anything like that. I can keep the 672 sq/ft open area of the shop cool with a 10.5K BTU 120V window unit. It was left over from another house and I didn't care to buy a new one. Attic temps run 110~120F in the summer. I used an 8K in the 288 sq/ft tool room because the LG had a really good fan for moving the air vs the cheap underpowered Frigidaire units. An 8K is "over sized" for the 288 sq/ft, I don't have any issues with short cycling. If I use the 48" tall post fan for circulation, I just don't run the unit on high.

If you have good insulation and some circulatory fans, plus keep the doors closed the 18K may be plenty. In this climate - hot, dry - I'd buy the 24K.

Thats the biggest draw back of window ac's,lack of cirulation.

 

[Richard Cranium]

If you are close to being to small always go bigger.