Power vent question

[kom526]

Ok, I want install a gable mount power vent in my house. The question I have is this: Can you go too large as far as cfm's? The attic space I'm venting is between 1900-2300 sq. ft. My gut tells me to go with the larger fan (2300 sq ft) just to be sure I get the ventilation I need/want. If the fan is a little large for the application then it shouldn't run as much because it would reach the set temp quicker. :shrug: I figure that there should be more emphasis on volume as opposed to square footage.

Thoughts? Experiences? Tips?

 

[Magnum]

Ok, I want install a gable mount power vent in my house. The question I have is this: Can you go too large as far as cfm's? The attic space I'm venting is between 1900-2300 sq. ft. My gut tells me to go with the larger fan (2300 sq ft) just to be sure I get the ventilation I need/want. If the fan is a little large for the application then it shouldn't run as much because it would reach the set temp quicker. :shrug: I figure that there should be more emphasis on volume as opposed to square footage.

Thoughts? Experiences? Tips?

Too much might suck your insulation out J/K

The only thing to watch is what ever air you are blowing out you are also taking air in. From where is the key. Depending on the configuration of your attic you might already have some outside air intake. You would need be sure to size an intake to whatever exhaust you are running.

 

[desertrat]

Too much might suck your insulation out J/K

The only thing to watch is what ever air you are blowing out you are also taking air in. From where is the key. Depending on the configuration of your attic you might already have some outside air intake. You would need be sure to size an intake to whatever exhaust you are running.

 

[Pete]

If your house whistles when it turns on it might be too big.

 

[kom526]

Well of course I have soffit vents for intake but I only have one gable vent (just a vent grille) for "exhaust". What I am trying to accomplish is to keep the temps down in the attic space and therefore reduce passive heating to the 2nd floor and extend the life of the shingles on my roof. I know this is a new house but I want to start the preventative stuff now.

So the soffit vents may not be enough for intake?

 

[kom526]

If your house whistles when it turns on it might be too big.

Can't....close...the...doors...

So if the walls go concave, that's bad. Right?

 

[Magnum]

Well of course I have soffit vents for intake but I only have one gable vent (just a vent grille) for "exhaust". What I am trying to accomplish is to keep the temps down in the attic space and therefore reduce passive heating to the 2nd floor and extend the life of the shingles on my roof. I know this is a new house but I want to start the preventative stuff now.

So the soffit vents may not be enough for intake?

Soffit vents should be fine, Just make sure the bigger fan has the same power hookup. You might even be able to get a variable speed fan if you are really worried about it being too much. It should be fine though, if not you ream out your soffit holes a bit for more free air space.

 

[Magnum]

I am sure if you are really worried you could factor the length and width of your soffit vent by it's free air space to figure out the total cfm that could pass through it.

 

[kom526]

Thermostatically controlled is the way I am heading. The particular fan I'm looking at has a thermostat and humidistat control box.

 

[yankee44]

If you are putting in a roof mounted vent and you have vented soffit be sure to block off your gable end vent or the new roof vent will pull the air from the gable vent and not from the soffit

 

[Dupontster]

I thought I was the only one to do something like this when the temp reaches 90 degrees....You know it is going to be over 100 in the attic....
I have 2 gable vents with a fan in each one...They come on around 100 to 120 degrees....I need to replace one now....It is rattling a little...Those things will cool an attic though....

 

[itsbob]

Thermostatically controlled is the way I am heading. The particular fan I'm looking at has a thermostat and humidistat control box.

If you oversize, won't you be moving more air, cooling the attic quicker, but causing your fan to cycle on and off more often? This would cause more wear and tear on the fan, and would shorten it's lifespan... Bigger is not always better..

 

[desertrat]

If you oversize, won't you be moving more air, cooling the attic quicker, but causing your fan to cycle on and off more often? This would cause more wear and tear on the fan, and would shorten it's lifespan... Bigger is not always better..

Yeah, but he's only talking about the high end of his attic footage. I'd bet that's what you should use.

 

[itsbob]

Yeah, but he's only talking about the high end of his attic footage. I'd bet that's what you should use.

Got it, I went back and re-read and understand it now, You'd be right.

 

[Charles]

850 CFM solar powered:
http://www.bigfrogmountain.com/atticfan.html

 

[czygvtwkr]

Also make sure that your attic access is well sealed. If you dont have enough intake area and the seal to your house is poor you could be sucking cold air out of your house into the attic. Yes this will cool the attic but you will be wasting conditioned air from the house.