AC for shop/shed

[paulsharvey]

We don't have a 'shop' topic? Anyway, I have a 24x28x7 pole barn shed/shop/dog house, that gets crazy hot. In the past, I've used cheap, old, used, window units ranging from 8000 btu to 5000 btu, and they've taken the edge off. 3.5 of 4 walls are roofing metal, with some 1/2" Styrofoam insulation boards. I'm fine with 85 and low humidity, 80 would be better, but it's a Very dusty environment. Between grinding dust, sawdust, dog hair, ect, the window units have lasted 1 or maybe 2 years. This is not meant to be cool; and doesn't need to heat, but it does need to be Cheap, and preferably something dust/grit resistant. Not doing MrCool type set up. What are yall using?

Current cut out is 15"×19", but can be modified easily.

Floor is broomed concrete, not dirt.

 

[paulsharvey]

Wife is more concerned with the dogs than me being comfortable working in there...

 

[MoKelly]

Wife is more concerned with the dogs than me being comfortable working in there...

Ha. My wife has a sign on her desk that says:

“Missing - husband, shotgun and dog.

Reward for dog”.

 

[ponytug]

(More) Insulation?
With more insulation, the units won't work as hard, or as long, and should last longer.

All the best,

Peter

 

[FPGT72]

The issue might be because the small size of the window AC you have been using. It likely runs the entire time.

In my shop I have a 240v 25000BTU "window" ac, and it has been in there for at least 15 years now, and (knock on wood) is still going strong. It will cycle on and off if I am out there long enough. My building is roughly your size but much taller.

I have a loft now, and it is really warm up there in the summer, I am going to do two things to help solve that issue, first is gable fans to pull that hot air out, the second is a smaller mini split. One reason I am going with the mini split is the heavy part is going to be down low, up high all I need is one hole.

 

[2manyrocks]

Basic BTU calculator: BTU Calculator

5-8,000 window units can barely cool a small insulated bedroom. With a larger, poorly insulated shop in sunny Florida, you'd probably need 25,000 btu if not 3 ton.

One advantage of mini splits is you only need about a 3" hole in the wall to run the linesets and power. Disadvantage is you must be meticulous about flaring and tightening the lineset connections to the correct torque to keep them from leaking, and you can't kink the tubing. Mini split can also provide heat.

 

[paulsharvey]

Basic BTU calculator: BTU Calculator

5-8,000 window units can barely cool a small insulated bedroom. With a larger, poorly insulated shop in sunny Florida, you'd probably need 25,000 btu if not 3 ton.

One advantage of mini splits is you only need about a 3" hole in the wall to run the linesets and power. Disadvantage is you must be meticulous about flaring and tightening the lineset connections to the correct torque to keep them from leaking, and you can't kink the tubing. Mini split can also provide heat.

So, let say I improve the insulation; we aren't trying to get to "room temperature"; just not dangerous; and workable (80-85, and get some/most of the humidity out). Is it better to run a smaller system constantly (well, in theory maybe 16-18 hr/day)?

So; the 5000 and 8000 btu cooled satisfactory; but they didn't last. Now; they both were over 10-15 years old, and taken out of a house the owner upgraded to mini-splits; but at the same time; I don't really want to buy a new $150-200 window unit every year. So, I guess the question really is; is there a better way to keep them alive in harsh environments, with extremely hot shed, undersized unit, with tons of dust/dirt/dog hair.

 

[paulsharvey]

So, back story; this started as a 12x16 3 walled, dirt floor, pole barn, that I build for approx $200. Since then, it's been expanded, concrete floor poured, ect. When I first enclosed the bigger footprint; it was fine 3 season; but summer; completely unusable. My first thoughts where swamp cooler or dehumidifier. The swamp cooler the issue is, you basically have 80-85 degree air, But 100% humidity. The dehumidifiers I've worked with at an old job, did keep humidity down, But they actually made a utility room hotter.

Hindsight being better, I might have done block walls; metal roof, with planned out insulation, like an R7 on the roof; but the way its built, it's hard to get a good air seal/decent insulation. I've bounced the idea around of using Kraken Spray foam; and even if I only get 1/2" of foam (R-3.5); I would improve the air seal.

 

[Runner]

My shop space is a 32 x 30 Perka building, which has 2 x 6 girts in the walls and ceiling with 6 inch (I think R-19?) batt insulation. I have a thru-wall AC/heat unit like this https://www.lowes.com/pd/Koldfront-...tioner-Heater-Included-with-Remote/5013393371 except I think it's about 13000 BTU. It is typically mid- 90's around here in summer and it will keep the temp at 80 on hottest days, usually cooler.

It helps to be strategic. If I know I will be working in there, I turn it on in the morning so it can maintain the lower night time temp and not try to cool it down from 85 or whatever by waiting to turn it on in the middle of the day.

My unit is older, completely manual, no thermostat or timer, etc., but when it dies, I will be buying a new one similar to the one posted above (only with as many BTU heat/cool as I can get) and with the timer and thermostat, assuming our government still allows them to be sold. Anyway, this has worked for me for a number of years with no problems and I would definitely do it again given the same circumstances.

P.S. The insulation made all the difference. I checked the temp. of the inside of the steel siding one day before installing the insulation and it was 130 degrees. The building was like an oven prior to insulation. I know this is obvious to anyone with two brain cells, but I was still surprised at how much difference even such a minor amount of insulation could make.

 

[JJT]

I'm not in Florida and my shop is well insulated.

"What am I using?" I have a single 10K btu window ac unit that I turn on if I'm spending any amount of time in the shop when it's hot out. It does an adequate job of cooling the bay I'm working in. No way could it cool the entire 1200 sq ft building. At my age I'm happy with a little cool/dry air moving around me while I work.