Box Fan to cool Attic

I just saw this video

http://www.youtube.com/watch?v=rhz78ukb0TY

regarding how to keep you house cooler in the summertime by cooling the attic with a box fan.
I was wondering what you guys think of it?
Do you think it would work?
Do you think there is a fire danger with the heat/electricity in the attic?
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wrote:

Anything that moves the hot air out of the attic space is going to help. This is just a cheap version of a Whole House Fan.
Whole house fans are better made, more durable, probably safer than a $15 box fan. It will also move more air.
Good side On a cool night it will suck in the cooler outside air and vent the attic
Bad side One hot day, you are sucking hot air through the house and while it may cool the attic, it may heat the living space more than keeping windows closed and shades drawn.
It does not reduce the humidity like an air conditioner.
Another option. Consider an attic fan that just vents the attic and does not suck the outside air through the house. That is the best idea when the sun is beating on the room. Use a fan built for those uses and keep your family safer.
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What kind of attic fan just vents the attic and doesn't suck outside air into the house?
Isn't that suction dependent on a number of factors, including, but not limited to, the size of the fan, the ventilation openings in the attic, the tightness of the house/attic junction and the tightness of the house itself?
It's not like you can go buy a fan that lists "doesn't suck outside air into the house" on the spec sheet.
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On 07/25/2013 08:10 AM, DerbyDad03 wrote:

What are we talking about here? I've seen two different arrangements, both which work but in different ways.
There's the "whole house fan" typically installed in a hallway ceiling that will suck air from within the living space and blow it into the attic; this not only cools the attic but draws (presumably cooler, when used at night) outside air into the living space.
There are also powered vent type arrangements that only move air through the attic to keep temps down in there in the summertime; those are typically controlled by thermostatic switches.
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On Thursday, July 25, 2013 8:10:50 AM UTC-4, DerbyDad03 wrote:

He means a regular attic fan that moves air from outside through the attic and not through the house living space like the whole house fan being discussed.
Like Ed said, the guy has just discovered the whole house fan. But he has some key concepts wrong. He claimed that hot air exits the attic via the soffits. There should be vents at the top of the attic, eg ridge vents, gable vents, etc where hot air exits. Cooler outside air should be coming in from the soffits. If you put in a powerful enough fan, you could reverse the soffit vent flow, but doubt a small box fan is going to do that.
He also says that his attic has poor insulation. Well, if that's the case, then that is costing at least comfort in the summer, assuming there is no AC and for sure $$ in the winter. So, why not fix that?
The main benefit from a whole house fan is not cooling the attic. It's about drawing outside air into and throughout the whole house. That works well if the air outside is cooler and dry. It' isn't very effective when it's 90F and humid outside. Or even at night when it's humid outside. I've thought about how much I could use one here in NJ and the answer is not all that much. Mostly some days in the spring and fall.
Also, while his concept would do something, a real whole house fan moves a lot more air, so it would be a lot more effective in moving air through the whole house. And obviously, all of the above is incompatible with having the house cooled with AC.
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snipped-for-privacy@optonline.net wrote:

I have a whole house fan. I also have central AC. In the Summer, the two are not compatible for cooling. You don't want to pull the cooler air out of the house. The only times I use the whole house fan is if I have to go into the hot attic and will be spending some time in there, or to remove smells or smoke from the house at any time of the year. Late one night, after letting the dog out to do his business, he got sprayed by a skunk. A bath with tomato sauce got him cleaned up, but the skunk smell was throughout the house. The whole house fan was on all night with all windows open.
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...snip

Yeah...I knew what he meant but to some extent I disagree with the words related to "venting just the attic without drawing air through the house".
I know you know all of this, but there is no fan that will specifically vent just the attic. It will be dependent on a number of factors such as intake vents (soffits, gable, etc) fan power, tightness of attic/house junction, etc.
If there isn't enough intake openings in the attic itself, the fan is going to pull air from wherever it can. If the house isn't tight enough, it's going to pull air from the outside.
To simply say "Consider an attic fan that just vents the attic and does not suck the outside air through the house" can be misleading especially to someone unfamiliar to the whole concept of attic ventilation.
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On Thu, 25 Jul 2013 10:49:25 -0400 (EDT), DerbyDad03

At 5:45 this morning I gave a basic and correct answer. At 8 AM you can do the engineering, do a layout, and write the installation instructions, pick nits.
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On Thu, 25 Jul 2013 12:10:50 +0000 (UTC), DerbyDad03

Sure you can. Any fan, in fact, can be made to do that. All you need is a gable vent at each end of the attic. Air comes in one end, goes out the other. No air enters the living space. Cools the attic.
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On Thursday, July 25, 2013 5:04:53 PM UTC-4, Ed Pawlowski wrote:

Now I have to disagree. DD has a point. Even with a gable vent in each end of the attic, you can't guarantee that no air is going to come from the conditioned space of the house. I'm assuming you mean that you put the fan in one gable and use the other to supply the incoming air. That fan lowers the pressure in the attic. The air will then come into the attic from any and all available routes. Most of it will likely be from the other gable vent. But some can be from leaks from the conditioned living space, eg around recessed ceiling lights, around switch plates, bathroom fan openings, etc. That is one of the big arguments against power venting an attic. And the effect depends on the CFM of the fan, the available intake openings, etc.
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wrote:

Sure, it'll help ventilate and cool that house. Real bargain basement way to do it, but it's a lot better than nothing.
I don't think much of it because I have A/C to cool my living space, and the attic is cooled by a powered roof ventilator pulling outside air in from soffit vents and exhausting it out the roof. Attic is insulated too. So they're separately ventilated spaces. But if I had his situation and wanted to spend the least money possible, I'd do something similar. When I lived in house with no A/C I used box fans a lot to direct outside air in the house. One in the living room window, and one in the kitchen window, both blowing air out. Then we'd get a "cool" breeze coming in the bedroom window, and sleep pretty well on hot nights - with no fan noise. That house was flat roof, no attic.
That guy basically put in what's usually called a "whole house" fan, on the cheap. It nothing but win-win for him really. All it has to do is knock a couple degrees off the living space and attic temperatures. And it probably does.
As far as "fire danger" if he uses good cords there shouldn't be any. That box fan uses very little current.
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