BuckR
Member
Planning on a 30x40x10 insulated metal barn.
Truss roof on 4" slab.
Question: Will a 25000 BTU a/c with heat pump handle it?
Truss roof on 4" slab.
Question: Will a 25000 BTU a/c with heat pump handle it?
Looking To A/C Shop
- Thread starter BuckR
- Start date
Farmall450
Well-known member
I don't have a clue, but I congratulate you on a Air Conditioned Shop.... 
Bronson
Well-known member
bump
kj_mustang
Well-known member
A manual J calculation is the best way to know how to properly size the HVAC for your shop.
kj_mustang
Well-known member
Something any competent HVAC contractor should be doing. I recently received three quotes for an AC system for my barn. One out of three of those contractors did the manual J calculations and he got the job. The other two were oversizing the unit based on the standard "this much sq. feet needs this much cfm" estimating.
Falcon67
Well-known member
What KJ said. The answer is "yep, sure, maybe, might work, buy it and let us know how it did" until someone does the heat gain, etc calcs.
It wouldn't heat that much interior volume here, unless it was air tight and you didn't open the doors in winter.
I expect your summers are warmer than ours so the AC load "sounds" high for that BTU.
Of course I don't know how well insulated "insulated" means to you, be that measured in R value, a given thickness of a specific insulation, insulated wall panels, ...
All of which makes it very difficult to estimate from here, which is another way of saying what KJ said (hire a professional that actually knows what they are doing
).I don't know the "Manual J" calculation (but I'm going to search, as I am scheming on a garage build
) but remember, dark colors on the outside are bad if your primary concern is AC.We have dark roofs up here so the sun can help reduce the snow load (sun shines through the snow, heats the roofing material up, warms the snow up enough that it just barely melts, or accelerates sublimation) it helps in winter, but can make for an uncomfortably warm home in the summer (if you are acclimated to 60*F, 85-90 in the house officially *****
).Another question that I never considered until I did my shop is do you want to keep it cool like you would a living space or have it cool down when you are going to use the shop.
I sized my a/c so that I could come home from work, turn it on, eat supper and have it cooled down enough to fairly comfortably work. Turn the unit off when I go in for the night.
Here in Texas I dont think I would ever have enough $$$ to try to keep it heated or cooled continously no matter how well insulated it is.
It also brings up some questions about how you are going run the inside unit and duct work. My duct work is as simple and short as possible to achieve max flow, small footprint and low cost. Since the duct work is in the shop and not in a attic there was no need to insurlate the duct work.
I sized my a/c so that I could come home from work, turn it on, eat supper and have it cooled down enough to fairly comfortably work. Turn the unit off when I go in for the night.
Here in Texas I dont think I would ever have enough $$$ to try to keep it heated or cooled continously no matter how well insulated it is.
It also brings up some questions about how you are going run the inside unit and duct work. My duct work is as simple and short as possible to achieve max flow, small footprint and low cost. Since the duct work is in the shop and not in a attic there was no need to insurlate the duct work.
jdub63
Well-known member
I'm running a 5 ton A/C in the same size shop. Like Imcrazy, I have the thermostat set for cooling during periods I'm normally in the shop. Last year during the really hot days 100+, I was able to keep it in the low 80s/high 70s. I found a used system on CL so I'm looking for a higher SEER unit this year.
Falcon67
Well-known member
1 ton AC = 12,000 BTU. Probably a tad more heat needed in SW OK than Azle but cooling would be about the same. Left Texas on vacation when it was hot and drove to OKC - was still hot when we got there. 
Bronson
Well-known member
Guys, Buck is a friend and he joined GJ on My recommendation to get solid answers for His shop build.
Buck, I think what these guys are telling you is that they cant give you concrete answers until they have more info on the actual build.
I didn't think to ask You, what color will the exterior be?
You know, darker colors will absorb more heat, good in winter, BAD in summer.
The main thing on the heating/cooling aspect is the type of insulation You decide on. The number of door and window openings , and how well they are sealed, is a big factor, also. You will want at least one, probably two, ceiling fans to circulate the air and even the temps.
I limited My 30x40 to one overhead door, insulated. Even with gap kits and seals, it is My biggest problem, HVAC wise. All five windows are double paned. Two insulated man doors.
I know You plan to use the shop as a hang-out primarily, pool table and bar, with space to work on the Harley, etc.
I can only urge you to get as much info as You can, before you actually build it.
DO NOT take shortcuts on the insulation or HVAC.
You won't enjoy the shop if it is 120 degrees in June, and 35 degrees in November, and the electric meter is spinning like a windmill.
Buck, I think what these guys are telling you is that they cant give you concrete answers until they have more info on the actual build.
I didn't think to ask You, what color will the exterior be?
You know, darker colors will absorb more heat, good in winter, BAD in summer.
The main thing on the heating/cooling aspect is the type of insulation You decide on. The number of door and window openings , and how well they are sealed, is a big factor, also. You will want at least one, probably two, ceiling fans to circulate the air and even the temps.
I limited My 30x40 to one overhead door, insulated. Even with gap kits and seals, it is My biggest problem, HVAC wise. All five windows are double paned. Two insulated man doors.
I know You plan to use the shop as a hang-out primarily, pool table and bar, with space to work on the Harley, etc.
I can only urge you to get as much info as You can, before you actually build it.
DO NOT take shortcuts on the insulation or HVAC.
You won't enjoy the shop if it is 120 degrees in June, and 35 degrees in November, and the electric meter is spinning like a windmill.
Well, the building is metal. A tan-ish color. It comes w/insulation which appears to be some sort of honeycomb coated with a plastic or latex layer. That comes with the barn. I plan on gluing up some of that 'Pink Panther' insulation as I finish the interior. There just happens to be a fairly new, unused ceiling fan in the garage. Hadn't thought of it 'til now.
Truss roof eliminates possibility of storage in the attic. Thinking of roofing felt for ceiling in bar area. That will eliminate a/c-ing the rafters, is cheap and should be fairly easy to put up.
Truss roof eliminates possibility of storage in the attic. Thinking of roofing felt for ceiling in bar area. That will eliminate a/c-ing the rafters, is cheap and should be fairly easy to put up.
Bib Overalls
Well-known member
I have a 1,200 with insulation in the walls and additional spray foam under the roof. I have a 3.5 ton heat pump. It works fine in my climate. My plan does call for more insulation but it is not critical right now.