Garage Ventilation using a whole house fan

[rackeu]

I am thinking of using a small whole house fan to keep my garage cool while working in it. I don’t need full time cooling. The garage is a 3 car and two bays are attached on two walls to the house with a heated and cooled bonus room over the top. The third bay is attached to the 2 bays but is an addition built separate on all sides with a separate small attic space above it. The 3rd bay will be my prinary work area and has a high ceiling to accomidate a lift when I can get funding for it. The entire garage is completely sheet rocked and the ceiling and walls of the 3rd bay have no insulation.

I understand that insulation would go a very long way but I think it would help just pulling the hot air out of the top of the 3rd bay of the garage. The attic area over the 3rd bay does not have a ridge vent, gables or any other vent other than full soffit vents around 3 sides. With that design I wouldn’t think there is any passive air exchange and I have a hot attic radiating heat down into the garage. There is nothing in the attic and nothing that would generate CO2 in the garage.

My thinking is that a small whole house fan would pull hot air out of the top of the garage which would also displace the hot air already in the small attic space expelling the air out through the soffit vents. In this manner I could get at least ambient outside temperature (with a breeze) when working in the garage. I guess it would also be possible to "steal" a little AC from the house if I left the door to the house open when I need something extra to take the edge off.

Can you see anything wrong with my logic? Is this worth giving it a try?

 

[fitz11]

I was just thinking about a similar system for my garage. Hopefully gonna put it to the test in the next few weeks. It sounds like a good plan to me

 

[MikeThomasNYME]

You are correct in that those soffit vents are doing nothing for you at the moment. My first goal would be to allow for proper ventilation of the attic space, it will keep some of the heat out of the garage, and will extend the life of the roofing. Ridge vents are not hard to add, assuming your existing roofing is not in dire straits. Reversing the flow through the soffits will likely blow insulation and debris into the overhangs, cutting off air flow.

As for ventilating the garage area, I would look at a shuttered exhaust fan mounted in the wall.

Something like this: http://www.northerntool.com/shop/tools/product_200331269_200331269

 

[Falcon67]

I plan to leave space for on of these:
http://www.northerntool.com/shop/tools/product_200459655_200459655
Not in the budget this year, but maybe next. It's a little big for a 960 sq/ft building but it runs cheaper than AC. It would be fine for many days - uh, but not like this summer where we set two records last Saturday: Morning low of 84 (highest low for that date) and 106 afternoon.

EDIT - the manual says it'll require (for vents I'm using) 12 6x12 eave vents and at least 5 9" roof vents. 1152 sq/in of vent. A lot.

 

[BHR4CE1]

If you have a gas HWH in the space, make sure the fan doesn't cause enough draft to blow it out.

 

[rackeu]

If you have a gas HWH in the space, make sure the fan doesn't cause enough draft to blow it out.

Nothing like that in there Frank. BTW looked at you thread nice build, would love to see it in person. Unfortunately, Mrs Rackeu and I will not make it but do enjoy the 2011 BD anniversary

 

[DuckSoup]

I'm thinking about doing the same thing.

There could there be a firecode issue leaving an opening between the garage and attic ceiling.

Google found this Garage Fan and Attic Cooler

Garages are fire rated. Does the GF-14 keep this fire integrity intact?

A. The GF-14 Garage Fan is equipped with a fire damper that is held open with a 212 degree fusible link to allow the air through the fan. In case of a garage fire this link melts and closes the damper keeping the flames out of the attic for up to 3 hours. Also the GF-14 Fan motor shuts off at 185 degrees.

 

[Motofixxer]

While and exhaust fan would certainly help. I think you would see a huge improvement in adding ceiling insulation. Anything to help keep that radiant heat from the roof from entering the main space. When I was building my shop, I noticed a drastic difference in comfort level when adding the ceiling insulation. Then you have the added benefit of being able to control the temperature level in there also like when heating etc.