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Need advice on venting garage and using attic fans

mikeinaz

New member
Joined
Dec 10, 2011
Messages
1
Location
Phoenix AZ
Hi,
This is my first post on here and I am looking forward to all of the knowledge everyone has, I will try to keep this as short as possible while providing details.

I live in Phoenix AZ, just moved into a newly built home and want to vent the garage with a solar roof fan to keep it cooler in the summer and also avoid super heated air sitting against interior walls. The home I just moved out of had one and it seemed liked it cut the temps down 30 degrees in the summer. So the garage is 4.5 car, about 1200sq. ft and above 3.5 of them is living area. So the one car bay of the garage(about 300 sq ft and connected to the others) has a traditional truss roof(uninsulated) above it but is only about 4' high at its highest point in the attic area so its not a lot of room up there to move around. In the roof is a gable vent as well as what I think we consider a ridge vent here in Phx, its a single vent near the top of one of the tops of the roof. I have seen where some people say you should not have a gable AND a ridge vent as it defeats the purpose. That leads me to my idea and questions.

I had bought a couple of solar operated attic fans a year ago and figured they would be good enough for this space I have. I was going to install one mounted against the a hole I will cut in the drywall on the ceiling and it will draw hot air up and out of the garage space into the area above the one car garage I mentioned. Then I was going to mount the second fan either against the gable or ridge vent to blow the air out of the attic space. So a few questions, the gable is easier to work with in this small area but is it better to mount the fan on the ridge vent so the warm air blows straight up and out(the natural path of warm air) or sideways out the gable? Does it even matter in this smaller application? Do I need to seal off the ridge vent if I put the fan in the gable as not to draw air from outside and to keep it pulling from the garage? There is also a small soffit vent(similar to the ridge vent but closer to the bottom of the roof) and should that also be sealed off as to not pull in outside hot air and allow it to only draw from inside the garage?

My last concern is, I have a gas water heater in the garage but its about 25' from where the vent would be in the drywall ceiling for the fan. The garage has two vents going outside near this whole 1 car/vent/project(per code in having a gas appliance in the garage) and I was going to just use this for my air inlet for the first fan mounted in the ceiling. I was told by a contractor that I cannot put a fan in the garage w/ a gas water heater as its a fire hazard. The suction of the fan can make the flame jump and cause a fire. These fans seem to be on the smaller side and from what I have read, solor fans dont move the same cfm as an electrical fan and the fan would be about 25' away like I mentioned. Is this a real concern and any ideas about it? Ok, I think thats it, thanks in advance for any feedback. Mike
 
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Garage Flooring

ALLIANCE MEMBER
Joined
May 21, 2011
Messages
5,288
Location
Grand Junction, CO
First let me say that your contractor raises a good point. I tend not to use the word 'Can't'. Solar Tube and Natural-light make solar attic fans. I would contact the manufacturer directly.

That said, any attic ventilation is only as good as the whole system. Lomanco is a great resource for this. If you have a RW Specialties in your area they will usually have someone who is VERY familiar with ventilation but you will need to go through one of their customers (local lumberyard, ProBuild, etc)

Houses today are being built tighter and tighter. Think of a coke bottle when you **** the air out of it. The pressure causes issues. If you are taking air out and do not have sufficient air exchanges, you are going to have issues... especially with B vent and wood burning appliances.
 
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lzenglish

Well-known member
Joined
Sep 3, 2009
Messages
616
Location
California
Use a Whole House Exaust fan to Pre-Cool your space, in the cool morning hours , and an Attic Exaust fan to compliment it when the temp. rises during the day. It does not matter how, or where the air is exausted, as long as it has a free path to do so. IMO

Wayne
 

SmokinFletch

Member
Joined
Mar 13, 2012
Messages
8
The water heater needs the fresh air and combustion air vents. These vents are to assist in the removal of Carbon Monoxide and products of combustion from your garage. Leave these alone.
 
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