Trying to cool metal shop building

[montyhp]

the problem with the swamp coolers is that they will make eveything in your shop rest. i sold mine after a year and bought a window a/c.

Also, swamp coolers work well in dry climates (had one in New Mexico that worked well), but OP is in North Carolina where it would just make everything damp and not really cool much.

I am looking at a mini split system for my current shop (muggy San Antonio, TX).

Montyhp

 

[carpenter383]

Not sure of the proper name for it, but my dad retired in Arizona and he calls it a swamp cooler. If this has already be answered my apologies as I read through the thread pretty quickly.

Yes "swamp cooler" is what I was thinking of:thumbsup:
As others have said it would be better suited in a dry climate than an already "moist" one.
I built my 40x36 garage with 2x6 walls and 12 ft metal ceiling with blown in insulation and it stays pretty cool in there even without a/c.
If I open the windows at night then close them in the morning the inside will only raise 10* max through the day. People think I have a/c when it's in the mid 90's outside and mid 70's in my garage Works out good if I don't have to open the overhead door and If I do It's just long enough to move a car in or out then I close it asap. (I use my garage for mechanic work not for everyday parking)
In the more humid times of the yr I do run a dehumidifier 'cause the floor "sweats" at times.
Another thing that helps is my garage is shaded for about the first half of the day.

 

[rswyan]

FWIW, this reiterates some of what has already been said:

I have a 28 x 36 metal building with two 10x7 insulated garage doors and one walk in door. The inside is open to the peak of the roof which is about 16 high.

...... the first problem .....

With it being open to the peak, all the heat (well, almost all ...) from the roof is radiating downward into the area you are trying to cool.

Ever been in an attic on a hot summer day ?

Well, that is what is coming down to visit ya .....

My polebarn currently is open to the peak ... on a sunny day - doesn't have to be hot - you can feel the heat radiating down on you (and that's about 14' at side walls and 20' at the peak)

The building is insulated with a thin foil/bubble wrap which is white on the inside and foil against the siding/roofing.

.... and the second problem ......

No, actually it isn't (insulated) .... bubble foil wrap (aka "Reflectix" that you can get at Lowes or Home Depot) is not insulation ... it's a radiant heat barrier ......

It is most effective when there is an airspace of at least several inches between it and the source of radiation (the roof, walls) .....

IOW, if the foil/bubble wrap was attached to the bottom of your rafters - providing a number of inches (6, 8, 10) of airspace - and it was completely taped (with foil HVAC tape) ...... well, it would probably do a fairly decent job ....... even more so if you have soffit vents and some sort of ventilation up high (gable vents at both ends of the building, even gable vent fans .... or, the best really: a good ridge vent that runs the entire length of your roof peak) .... to allow the warm (hot) air to escape by means of convection.

A quick and cheap fix might be to go pick up some 6/8/10 mil plastic sheeting (clear, not black) and staple it up to the bottom of your trusses .... probably cost ya less than 75 clams .... and you have just significantly reduced the air volume that that little 24K BTU AC unit is trying to handle ....

FWIW, I have a small (28 x 32) garage/workshop/equipment shed here, in addition to the polebarn .... it's concrete block, shingle roof ... about 8' ceilings ..... the walls are entirely uninsulated - just block .... and on a hot sunny day, in the middle of the afternoon, it is amazing how much heat the interior west wall (block) will radiate around.....

It has a small wall AC unit .... maybe 7.5K or 10K BTU .... dunno, I'd hafta look ...

It will keep the shop relatively comfortable even on hot days (90's) .... if I turn it on in the morning and leave it running ...... but the ceiling is drywalled ..... and there is fiberglass insulation above the drywall ....

On a hot day the attic is like a sauna .... (no ridge, soffit, or gable venting)

Of course, if ya would like to ensure that your local electric utility isn't lacking for users of their product, then just go ahead and buy a larger unit .... and watch the meter spin ....

The fact is that I paid an additional $1800 for the insulation that was installed with the building, and it works fine for heating.

Well, quite honestly .... no, it probably doesn't ..... if it were really working fine for heating, your energy usage cost to heat it would be far less ... (although it may be fairly minimal considering your location)

..... you just aren't noticing it .... because the size of your heater is large enough to overcome the heat loss .....

If it's taking 45K BTU's to heat it, in it's present state, then yeah - ya might want consider a similarly sized outside unit to cool it - or just grab another 24K BTU window unit slap that in there too ..... and, in either case, watch the meter spin ......

Of course, neither of the above would be the best, most efficient solution ..... (reduce the volume of the space you are trying to heat/cool and insulate)

The inside of the shop is wide open, so my thought is that just dumping the cool air into the shop would work.

Yeah .... so would very large blocks of ice ...... provided you had enough of them ....

You are attempting to address only half of the problem - remember the Zeroth law of thermodynamics:

"When two systems, each in its own thermodynamic equilibrium, are put in purely thermal connection, radiative or material, with each other, there will be a net exchange of heat between them unless or until they are in thermal equilibrium"

Without something to stop it, heat flows to where it isn't .....

That's how it works in the winter ..... and how it works in the summer ... anywhere in the universe ......

 

[Hawghauler]

My 32x40 shop has about 1 inch thich white vinyl backed insulation. I bought 1/2 inch plywood to cover the 12 foot vertical walls to create an airspace to augment the insulation. I haven't tacked it up yet, but it is on my "list" of things to do when I get my next R&R. I will paint it white to brighten it up. I use a diesel salamander for heat and may put a pellet stove I have in it. Canyon county can get mighty hot and dry so ac may be difficult. It tops 100+ consistently. If I can get it down to 80 I'll be very happy. Being in the mid east for years where it frequently gets 135+ degrees, I find 80-90 quite balmy. I have been setting the shop up as my man palace complete with tons of tools, compressor, killer stereo Hellen Keller could hear, guns, lighting you need sun screen for etc. I need a refrigerator and a could bottle opener still and I have plans for a urinal. Hard to compete with a man who has his own urinal. Women wouldn't understand.

 

[mjarrels]

I cool mine in the winter time. Heat it in the summer.

mark

 

[Big Bri]

I cool mine in the winter time. Heat it in the summer.

mark

WHOW. . . I'd Hate to see those electric bills

 

[kebo]

If there is any way you can put an insulated ceiling in there it would be a major help.
Walls too, you need a heat barrier before you can efficiently maintain a warm or cool shop.
If insulation isn't an option there is a product that sprays a fine mist of water (can't remember the name) the water mist is directed toward you to help keep you cool.
Might not be a good idea if mold is a concern though.

If you have a well, a trick used quite often to help cool buildings with metal roofs is to direct a sprinkler onto the top of the roof so it stays wet. That will drop the temp of the metal roof probably about 20-40 deg. It would only need to run on days you know you will be using it. Also, if possible, paint the roof a light color or use the silver roofing paint that you see on a lot of barns.

 

[CurlyDave]

...Hard to compete with a man who has his own urinal. Women wouldn't understand...

When we bought 40 acres, my wife thought I should get an outhouse to put at the far end. I told her that no guy with 40 acres needed an outhouse. Same with a urinal.

Now if it gets really cold in the winter, then I understand.