Attic Fan

[lzicc]

In my garage, I have pull down stairs to get to the attic so I can use it for storage. The peak height is about 7'. It get's hot up there when it is sunny out and I want to cool it down some when it is hot out just so nothing I store up there gets ruined from the heat. Do attic fans work for this? I have a 4' foot over hang in the front of the garage that has all perforated soffit and I also have a ridge vent that goes across the peak, so I would have plenty of air flow. The ceiling of garage is insulate also.

I am looking at either the roof mount and the gable mount attic fan with an automatic thermostat.

 

[Gary S]

My best advice is to forget using an attic as storage. It isn't much better than piling things outside. If you need storage, build a storage shed. Attic fans are usually set to run whenever the temp up there gets above 90 or so degrees. That means even with it running on a hot day, the attic is likely at 110-120 degrees while the fan is trying to beat the heat from the sun. Put in the attic fan to help on your house cooling bill but forget about using that space as storage. Build a shed, and not a tin can shed because it will be just as bad as using the attic.

 

[5lima30]

I put in a end gable vent thermostatically controlled fan this year. It has made a huge difference! My garage which has no shade rarely gets over 73F even when it's in the mid 80's. BTW, I got mine from Northern Tool on sale for $50.00 and it was made in USA to boot!

 

[lzicc]

I thought about putting in a gable fan in on one side of maybe a window on the other side. I just want to keep the air up there somewhat tolerable. I don't need the window for the ventilation since i have such a long overhang, but I was going to put one up there anyhow. When it is hot out and I go in the attic, it is instant sweat.

I am concerned about the fan being able to cool the attic like Gary mentioned since the radiant heat from the roof gets so intense. The fan I am looking at is 1600 CFM and my attic is about 1000 sq with a 5/12 pitch so I would think that would be more than enough for that area.

 

[65Stang]

My house fan moves the air to help keep the house cool, but the attic space is still very hot. The attic can't be cooler than the air it is sucking in and will actually always be hotter than that due to heat being absorbed.

 

[Falcon67]

I thought about putting in a gable fan in on one side of maybe a window on the other side. I just want to keep the air up there somewhat tolerable. I don't need the window for the ventilation since i have such a long overhang, but I was going to put one up there anyhow. When it is hot out and I go in the attic, it is instant sweat..

Won't work because of your ridge vent. An exhaust fan will just pull air from the ridge and not the soffitt. You would probably need to do what I'm going to do - mount a 16--cfm fan in the ceiling and pull air from the inside of the shop into the attic. Then you don't care where it exits. I'm doing it more for venting the lower garage and not the attic - I used TechShield decking and the attic barely gets to 110F. The ridge board was 105F last time the building sat in 100F weather all day.

 

[Matt M PA]

The storage area and upstairs of my garage got very hot indeed last summer. The storage area is above one of the bays...then it's open between the second floor ceiling and roof. I have a ridge vent.

I put a gable end thermostatic fan with the vents that automatically open and close as high as possible in the wall. When on, it pulls a heck of a draft from the area over the ceiling, storage area and I'm sure the ridge vent.

Is this the "best" way to do this? Maybe not...but it's made a huge difference in temperature in those areas. In fact, after it was in place and working I went into the storage area and pulled the door closed behind me. I was suprised how well it pulled.

 

[BHM]

As Falconed mentioned, the ridge vent will probably reduce the effectiveness of the fan. You will see some improvement but not much. If you are determined to store stuff up there, you want a cross ventilation setup. The fan needs to draw air across the entire attic space bringing in cool air and exhausting hot air. You would benefit by installing a radiant barrier to the underside of you roof.

At best, it will never be cooler than the outside air unless you are able to stop all forms of heat from entering the space which is impossible to do. You can only hope to lower the temps which may or may not have any real affect on what you are storing up there.

 

[BWS]

Falcon's got it..............


We call them,"whole house fans".Been around as long as electricity.They mount in ceiling of living/work space.They'll come with louver'd slats that close when fan shuts down.Ours has a 3 sp motor.

In Winter....we take the knob off switch,carry it to attic where its hung on a nail.Then cvr fan up with an old rug and then throw some insulation on it.The knob is right there when the thing gets uncvrd in Spring.

They work because it turns attic into a positive flow....IOWs,the air that enters attic can only be forced OUT of any venting.Just make sure theres no way for air to get back into living space.

 

[lzicc]

It's a stand along garage so there is not an issue with the living space. I just don't want to put one in and not notice much of a difference.

 

[Falcon67]

Just watch your vent area vs the fan CFM - a whole house fan moves about 4500 CFM, way more than minimal roof venting can handle. A ridge vent could probably handle that, depending. I have 5 each 10" round static vents plus 10 eve vents, so 1600 CFM is about all the building can handle without blowing air back down through the gaps between the OSB ceiling panels or increasing the static pressure enough to cut the fan efficiency.