I Need Some Advice

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Forum topic by Monty Queen posted 03-31-2011 06:54 PM 1938 views 0 times favorited 16 replies Add to Favorites Watch
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Monty Queen

1593 posts in 3214 days

03-31-2011 06:54 PM

Topic tags/keywords: question

I have a 12X24 metal shop, i want to cool it this summer with fans. Blowing the hot air out, i know it stll be warm but i want the shop to have moving air or ventilation. I want to know if attic fans in the windows would work i am tottaly lost when it comes to this subject. I have a 110 air conditioner in there but it dose nothing in the hot South Carolina summers. Can you please give me some advice.


-- Monty Q, Columbia, South Carolina.

16 replies so far

View bandit571's profile (online now)


19712 posts in 2646 days

#1 posted 03-31-2011 07:20 PM

That large pole barn I work in has two large double “barn” doors. One to the north, the other to the east. Gets a nice breeze going through.

Maybe, if you can, install the fans through the roof. This will draw the hot air out. You’ve seen the older barns with a little shed on the roof? That is the barn’s way of releasing all the hot air in the roof area, drawing cooler air in from the ground level. They do make a “wind-turbine” for roofs. Non-electric, the hot air coming out starts the spin, any breeze in the area will keep things moving.

How big are your doors? Keep them open while you are working in there.

-- A Planer? I'M the planer, this is what I use

View canadianchips's profile


2600 posts in 2959 days

#2 posted 03-31-2011 07:29 PM

Air conditioners need enclosed spaces to work efficiently. Doors closed,windows closed and no vents. Similar to a refridgerator. Open the door and it will not keep up cooling inside.
Before buying a fan, go to a local farm supplier that sells fans, tell him what size of building you have and how many times you want the air to be changed, he will have different size fans (cfm) that will work for you.
You don’t need a fan that will BLOW your hat off every time its runs and on the other end you need one large enough to keep FRESH air moving all the time.
Fans in the upper windows will move the hot air out, you will also need some vents at a lower level to bring fresh air in. Size your vents according to the fans you are using. Chicken barns are perfect examples of NEEDING good air quality. Fans and vents are sized as needed.

-- "My mission in life - make everyone smile !"

View 8iowa's profile


1580 posts in 3723 days

#3 posted 03-31-2011 07:33 PM

You know, for a 288 sq ft shop, that 110V air conditioner would probably do the job if you were to insulate the building. Insulation is not that expensive.

I used to work in a non air conditioned garage in SW Florida. The heat and humidity could be unbearable. A fan was not much help. It’s hard to work with sweat dripping down on your work and tools, and your glasses fogging up.

-- "Heaven is North of the Bridge"

View a1Jim's profile


117060 posts in 3539 days

#4 posted 03-31-2011 07:47 PM

In small houses I’ve lived in I used a whole house fan ,they move lots of air and are not to expensive.

-- wood crafting & woodworking classes

View tenontim's profile


2131 posts in 3707 days

#5 posted 03-31-2011 07:51 PM

After looking at the photos of your shop, you might make a little headway with your a/c if you were to put the foam insulation board, just on the ceiling of your shop. Then you could use the a/c with a fan or two to circulate the air. I have an insulated shop, with an a/c, but I don’t run it with the thermostat set real low. Just enough to take the edge off the heat, then I have a couple of fans that keep it comfortable.

View sawblade1's profile


754 posts in 2989 days

#6 posted 03-31-2011 08:14 PM

Check out this link saw it in one of my woodworking catalogs once before

Wish you the best of luck with keeping cool :)

-- Proverbs Ch:3 vs 5,6,7 Trust in the lord with all thine heart and lean not unto your own understanding but in all your ways aknowledge him and he shall direct your path

View Gregn's profile


1642 posts in 2946 days

#7 posted 04-01-2011 01:15 AM

I would have to concur with insulating as well. Even covering the walls with just OSB or drywall will make a difference in the way your A/C unit works by creating a dead air space between the walls. A 8000-10000 BTU A/C should adequately cool your shop. I would think that the noise from a attic fan running all the time in that small of an area, while your working would take away from your woodworking enjoyment.

-- I don't make mistakes, I have great learning lessons, Greg

View Roger's profile


20923 posts in 2766 days

#8 posted 04-01-2011 02:49 AM

absolutely, insulation. Looking at your shop, I see metal walls, and metal roof, with studs, but no insulation at all.
I think you’d have to have some sort of air gap, or barrier, ? between the metal roof, and the insulation itself. Someone on here should have some expertise on that.
p.s. I did have a friend that had a “Quanset” style auto shop w/o studs. His metal had insulation that was blown onto it like paint.

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed.

View adaughhetee's profile


104 posts in 2646 days

#9 posted 04-01-2011 03:17 AM

I have an attic fan mounted in a base with guards. It’s on caster’s and move’s a lot of air. For it to work good you have to use it to pressurize the room to move air through instead of just stirring it. I have considered mounting it in the ceiling which I think it would work a lot better. After looking at your shop I think that an attic fan would turn you size shop into a sawdust tornado. Mine blows sawdust around in my 30’x30’ garage if not pointed the right direction.

View ScottN's profile


261 posts in 2642 days

#10 posted 04-01-2011 04:10 AM

I also took a look at your shop and I have to agree, you definitely need insulation.

-- New Auburn,WI

View Jack_T's profile


623 posts in 2994 days

#11 posted 04-01-2011 05:00 PM

I also have looked at the photos of your shop. Its a real nice shop. I like the color of the siding. Its light and should reflect some of the sun’s rays. I can’t tell what color the roof is. If it isn’t a very light color, you should paint it white to reflect as much heat as possible. If it is a light color I would leave it alone.

I agree that you definitely need to insulate the shop. Right now your shop walls effectively create an oven. The sun heats the metal which heats the air inside. Insulation has two benefits. The first is that it will help to lower the temperature in the summer by reducing the radiation of the heat into the shop in the summer. The second is the exact opposite. It will help to reduce the loss of heat from the shop in the winter (through in a space heater and you have a year round climate controlled workshop for very little monetary investment). Insulation isn’t very expensive. It looks like you stud spacing is 24” on center. A Columbia, SC Lowes carries R-19 23”x93”x6.5” 9 to a pack for $64.76(for the ceiling) and R-13 23”x93”x3.5” 7 to a pack for $87.04 (for the walls).

You should also check the Btu rating for your air conditioner. I have copied a table matching Btus to square footage below. I hope this helps you.

Figure the Correct Size

The cooling capacity of room air conditioners is measured in BTUs, or British Thermal Units, per hour.

To figure the size unit you need, measure the space you’re trying to cool and find it on this chart. To estimate square footage, multiply the length of the room by the width. (A room that’s 10 feet by 20 feet, for example, has 200 square feet in it. The chart shows the recommended air conditioner for that sized space is rated at 6,000 BTUs.)

To cool this area Look for this size air conditioner
100 to 150 square feet 5,000 BTUs
150 to 250 square feet 6,000 BTUs
250 to 300 square feet 7,000 BTUs
300 to 350 square feet 8,000 BTUs
350 to 400 square feet 9,000 BTUs
400 to 450 square feet 10,000 BTUs
450 to 550 square feet 12,000 BTUs
550 to 700 square feet 14,000 BTUs
700 to 1,000 square feet 18,000 BTUs
1,000 to 1 400 square feet 24,000 BTUs

When looking for the correct size air conditioner, keep these suggestions in mind, as well:

If the room is heavily shaded, you can reduce the BTU capacity by 10%

If the room is very sunny, you should increase the BTU capacity by 10%

If more than 2 people regularly occupy the room, add 600 Btu for each additional person

If the unit is for a kitchen, increase the capacity by 4,000 Btu/Hr.

If you don’t want to insulate I would definitely vent the roof. It is the best way to evacuate the hot air.

-- Jack T, John 3:16 "For God so loved the world that he gave his only Son, so that everyone who believes in him might not perish but might have eternal life."

View devann's profile


2246 posts in 2655 days

#12 posted 04-01-2011 05:31 PM

Hello Monty, I have a shop here in Texas and it get’s stifling hot. I have some fans that move a considerable amount of air. But what I like best is a fridge in the tool room stocked with plenty of cold drinks, mostly beer. Of corase after hitting the fridge I spent most I my time at the picnic table in the shade. Have a good 1st day of April Monty.

-- Darrell, making more sawdust than I know what to do with

View RetiredCoastie's profile


999 posts in 3145 days

#13 posted 04-01-2011 05:31 PM

As a few have said, sprayed in insulation and drywall. You need the insulation to be bonded to the metal or your gonna have a condensation problem. I’d get a free estimate from a spray insulation contractor and then check out what it would cost to rent the sprayer and buy the chemicals. In the end you’ll be money ahead.

-- Proud Supporter of Homes For Our Troops

View ScottN's profile


261 posts in 2642 days

#14 posted 04-02-2011 01:10 AM

Spray on insulation? Condensation? hmm….nah…I don’t think so.

-- New Auburn,WI

View RetiredCoastie's profile


999 posts in 3145 days

#15 posted 04-02-2011 01:54 AM

If there is a gap between the insulation and the metal siding you will have condensation form on the metal. I’ve seen it numerous times.

-- Proud Supporter of Homes For Our Troops

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