Workshop Cooling

[Dave Richards]

I hope this is on topic enough to put it here.

I was thinking during my walk to the bus stop this morning that I should see about doing something to help reduce the summer heat in my garage, er I mean shop, yeah, shop. :D

The shop is a two car attached garage that doesn't share with cars. It is insulated and sheetrocked including the ceiling. Problem is, the ceiling is several feet higher than the top of the door and when it does get hot in there the heat tends to stay in. I was thinking that perhaps I could put a ceiling mounted exhaust face up to exhaust heat into the attic space. The attic is vented with soffit and ridge vents. I had in mind something like I drew in the attached image. For the winter I figured I could make an insulated cover that would attach with latches so it could be closed up tight. In fact I'd probably mount the fan higher in the box to allow more insulation in the cover.

My concern is fire in the shop and it spreading into the house. The entire wall between house and garage is sheetrocked with a double layer over OSB sheathing, even above the garage ceiling.

Any thoughts on this idea?

I was also wondering about putting a thermostat on the fan so it would kick on if the temp got above a set point. It occurred to me that I probably wouldn't want it to kick on in the event of a fire, though. Any thoughts on how one could wire a fire detector into the fan circuit? I don't imagine a smoke detector would be appropriate in a woodshop. Maybe that sort of thing isn't worth the cost either.

http://img.photobucket.com/albums/v506/weekender410/ceilingfan.jpg

[Doyle Alley]

This probably won't make you feel any cooler but us poor schmucks down here in Florida and Texas have to live with the heat constantly. I'm assuming you don't want to air condition the shop - just vent out some of the captured hot air. The problem I see with venting into the attic is twofold. First, there is going to be a tendency for some of the attic heat to radiate down through the vent when it isn't on. Secondly, the amount of hot air you can blow into the attic is going to be limited by how fast it can escape through your attic vents.

I would put in a thermostat controlled power attic vent on your roof. Then, if you find that that doesn't cut it alone (it probably will), buy a small "whole house fan" to go into the ceiling. When the ceiling fan is going in conjunction with the powered attic vent, you'll be able to move a fairly large volumn of air. The first problem I mentioned can be mitigated by buying a good quality fan with automatic closing louvers.

Of course, during your serious winters up there, you'll probably want to put some kind of additional cover over your ceiling vent fan to keep from loosing good heat.

I don't see what your real concern over fire is. If it bothers you that much, get online to the marine supply industry and look for an engine compartment automatic fire suppression system. They aren't terribly expensive and can be installed in your attic. The inboard boat I used to have had one in it.

[Dan Oelke]

First - check with your local building inspector on anything - they have the final say.

What you are talking about sounds like a "whole house fan" that is meant to be installed in a house to provide similar cooling effect. The complicating factor you have is the firewall. Some houses are constructed with even the attic space of the garage having 5/8" drywall between the house and the garage. In those cases you can then have thinner drywall on the ceiling of the garage. Since you said that you have 5/8" drywall on the ceiling you probably don't have that firewall in the attic.

Since the fan and it's outlet will be breaking the firewall of the garage you need to handle that someway. You could put drywal between the house and the garage in the attic. You might be able to build a drywall box around the outlet of the fan.

I wouldn't worry about shutting down the fan in case of a fire - but I would worry about making sure a fire in the garage can't easily spread from this big hole into the rest of your house.

[Tyler Howell]

Dave,
If you can vent (even with convection) the atic then I think you will be well ahead.
Simple ceiling fans offer a lot of relief during periods of mild stress

[Dave Richards]

Doyle, a fan in the roof is probably a good idea. There seems to be a fair amount of circulation up there now with the full length ridge vent and all the soffit ventilation but a fan might be a good addition.

Don, good point on the inspector.

I've been up in the attic and know there is a firewall between house and garage attic. Still, I get concerned about cutting more openings in a house anywhere. Out of curiosity, where did you see 5/8" sheetrock mentioned?

Tyler, I thought about convection, too. Right now there's no where for the heat to go so some ventilation seems like a good idea.

I'd like to be cool like you. :cool:

[Dan Oelke]

I didn't see 5/8" mentioned - at least not now that I went back and re-read the post. I read about double layer of drywall which like 5/8" drywall gives you firewall rating. My brain short-circuited and equated firewall rating with 5/8" drywal. Sorry about that.

Just a cheap ceiling fan might do the job for you just as well - when you open the garage door you get good cross ventilation and then the ceiling fan keeps the heat from sitting up near the ceiling. Nice thing about a ceiling fan is that you can often find one cheap - especialy when the ruler of a household decides that the current one needs to be replace with something that looks nicer. - (as I look around to make sure the LOML isn't looking over my shoulder.)

[John Gregory]

I have a whole house fan in my home. I replaced the swamp cooler 11 years ago and mounted the whole house fan in the ceiling where the cooler was. We love it. When the temp outside gets lower than the temp inside, we open the windows and turn on the fan (turn off the A/C of course) Besides pulling in fresh naturally cooled outside air, it cools the attic too. It forces the hot air out of the attic via soffit vents and turtle vents. Saves money and wear an tear on the central air unit.
In Utah we usually have nice cool evenings. This might not work everywhere. but our highs and lows in the summer can change by 30-40 degrees. Humidity is low too.

The whole house fan has louvres that close when turned off and open with the suction of the fan. Works so well for us, my FIL and BIL put ones in their homes.

John

[Ben Grunow]

I would not recommend cutting a hole through what appears to be a fire rated envelope. Someday you might put cars back in there and a fire would be allowed to enter your home rapidly. I would heavily insulate the garage ceiling to R-38 or more if it is not already and put the largest through wall ventilation fan you cna get on the side opposite the garage door if possible. This way you retain your fire rated garage (as required by the Building Code), improve the shops efficiency in summer and winter and the fan you will need to go through the wall will be much less expensive than a roof mounted unit and you don't have to cut a hole in your roof (which is never any fun).

You can get a fan unit with whats called a "fire damper" that is designed for installation in a fire rated wall. I think it has a fusible link and heavy springs that close a series of thick steel vanes (like a window blind) when a fire burns the link out-read heavy, complicated and expensive. Good luck and hopr this helps.

[Brad Townsend]

Since you are well insulated and you are going to all of the trouble of knocking a hole in the ceiling, etc. forget the fan. Put the hole in the outside wall instead and install a window AC unit. You will be much more comfortable and it won't cost that much more. It wouldn't even have to be a new unit. Used window ACs are readily available. You would be cooler and dryer as well. I've got an 18,000 BTU unit in my 20'x30'x9' (ceiling) shop and it's more than adequate. I only run it when I'm working and I don't really notice it on the electric bill.

Perhaps air conditioning a garage (particularly in Minnesota) seems extravagant, but it can get VERY hot in your area in the summer and all the fans in the world aren't going to make you want to be working out there when it's 90 degrees.

[Jeff Eiber]

I have had a wind turbine in my garage for about two years. In the winter I block the hole from the inside with a block of styrofoam. In the summer I leave the garage door up about 1" at night to let in cool air. The cooling is satisfactory except for about 2 weeks in August here in Cleveland.

[Matt Moore]

You might want to think about where the air is going to come from to replace the air that is vented to the attic. You will have to open a window or the garage at least a little to allow the air to flow.

I would also suggest a window air conditioner. Here is a link to a thread that I put a picture of my setup which was a bit complicated since I did not have a window to put it in.

http://www.sawmillcreek.org/showthread.php?p=363127&page=2

[tod evans]

dave, here`s a novel idea:)

39291

[Aaron Koehl]

What prison did you get that from? :D

In all seriousness, those fans are wonderful..

[Frank Chaffee]

What prison did you get that from? :D
tod probably fashioned some wings, turned the baby to high, and flew out!

But seriously Dave, I would think that unless you are going to AC the shop, either the ceiling fan or barn fan will give you the most comfort.

Frank

[tod evans]

What prison did you get that from? :D

In all seriousness, those fans are wonderful..

that fan came out of an old chicken house, it`ll blow a good breeze through 4k ft with a lil`ol` 1/2hp motor, i tried a 1 1/2 with a bigger pulley but it tried scooting itself around, just too much air!

total cost including cheap castors less than 40 bucks....tod

[Joe Mioux]

dave, here`s a novel idea:)

39291

That and a Really big block of ice.... and you are set!:D