Whole House Attic Fans ??

[billt]

This is for TAB, and whomever else has had one installed, or knows about installing them. What type do you have, and how do you like them? I had one back when I lived in Illinois. It was a roof mounted model. Several people had them, and they worked well. What's funny is when I moved out here to Arizona, you see very few of them, and I don't understand why? Attic temps. out here in the Summer months can easily reach 150 F when it's 118F in the Sun. In fact some cities like Lake Havasu have an ordinance in the Summer that one man cannot go into an attic without someone staying in the living area to monitor him, in case they should pass out. (Some years back they had an air conditioning contractor pass out and die in a hot attic).

Anyway, I want to install one. I can't do a roof model because I have tile. But instead want to do a gable vertical mount. I have gable vents at each end of the house, and one over the attached garage. So I'm figuring if I mount the fan on one of the side gables blowing out, it will draw air through the attic from the other 2 vents. (There are also vents running the length of the eaves). There is 110V nearby to tap into. This is the type of fan I'm looking at.

 

I've seen better one's that come already mounted to a square wooden frame, but you get the idea. These type of fans usually run around $250.00 depending on size and quality. I'm wondering what I should be willing to pay for installation without getting ripped off? If anyone has had one of these type of fans installed, I'd appreciate hearing what it ran you for the whole job.

I would attempt it myself because access isn't bad. There is a wood covered walkway in my attic, and plenty of head room because it's near the peak of the roof. I'm just not real good with electricity, or fishing it into interior wall switches or automatic thermostats, and that sort of thing. And I don't want to wind up burning the joint down.

[alfsauve]

I have one and it died recently and needs to be replaced.    The last I bought one they were around $30, now easily $100 and up.  I don't understand why a direct drive fan and motor can cost so much.  I mounted mine on a plywood backer myself and then screwed that to the opening on the far end of the house.

There are all sorts of passive systems as well as solar ones but I prefer this method myself.

[billt]

The problem with solar is they don't move that much air. From what I've been able to read on these things, a pulley belt drive model moves more air, and is much quieter than a direct drive model. They also cost more. I'm more interested in getting a good one that has a motor with good bearings that won't cook in the hot environment it has to run in.

[tombogan03884]

The reason you don't see them in your area is because they lower indoor air pressure and suck in dust like a vacuum.
Seems like a good idea bow, but Mrs Bill will not thank you.

[Rastus]

Tom has a good point Bill.  But are you going to stand up like a man and install one anyway or wimp out?   

And gee golly you've been up to a lot of home projects lately.
If you open up more of your eaves there will be less draw from inside the house that Tom pointed out.  In the old houses in Louisiana eaves were open all around but newer houses have fewer opening (less square inches for ventilation).  Up here in Oklahoma their are even less eave openings.  I think the lesser openings has to do with saving $$$$'s on construction.

If Tab chimes in we'll get some pretty solid answers. 

You may want to put in ridgeline vents?  I'm doing that with my next shingle project and adding passive vents.  Personally I stay away from powered vents because of the infrequent fires they cause. 

If I ever build a house I'll have enclosed rafters where the eaves vent directly under the roof and exit on ridge vents at the ridge line.  In this system the cooler air comes in and flows directly under the hot roof maximizing cooling and lowering temps.  The enclosed rafter also absorbs some of the heat from the roof which the direct air flow carries away.  Then you have to account for the isolation of the attic from air flow and some vents for the attic at gables or with dormers as well as pierce the isolated rafter system at a few high points for exit.  This costs more but works very well. 

If we get a Killary as president no doubt we will have a recession and be negatively impacted.  Money you spend to make your house more livable that lowers energy use should help your future nearly uaffordable energy bills in the coming recession.

[Sponsor]

[billt]

The reason you don't see them in your area is because they lower indoor air pressure and suck in dust like a vacuum.

Evaporative coolers do that far more, and they're everywhere out here. My attic is not connected to the living area by any vents. In Lake Havasu I had a Mastercool evap cooler with up duct discharge. (Without up ducts you have to have windows open to allow air to exit the home or you will pressurize the interior). With up ducts it discharges the cooled air into your attic and out the attic vents, cooling it to near the inside temp.

The problem with evaporative coolers is you can't run them if the dew point is over 55%, or you will muck up the house with too much humidity. That's why I just have A/C in this home. But all this attic fan will do is exchange cooler outside air into the attic, replacing hot air trapped in the attic. I'm not seeing how dust would be a factor inside the house?

[billt]

You may want to put in ridgeline vents?  I'm doing that with my next shingle project and adding passive vents. 

I can't do ridgeline vents because I have a tiled roof. My house in Illinois had them, but it also had asphalt shingles. Tile roofs really limit venting and such. That's why most of the homes out here have gable vents, and or eve vents. I have both, so with a fan it will be able to draw plenty of fresh air into the attic from the outside.

We do get dust storms during Monsoon season, (usually from early July until mid September). That would be the only time I would be concerned about sucking dust into the attic. All I would have to do is have a manual switch, so I can shut it off during any dust storms until they pass. They usually don't last but a few minutes.

[jaybet]

Bill you  are talking about an attic fan. A whole-house fan traditionally is a big fan set in the ceiling somewhere that draws cool air through the house, up and out through the attic area. That type of fan would definitely give you a small negative pressure causing wifely consternation at the dust levels.

You're on the right track drawing in one gable and out the others. Also make sure your attic access seals pretty tight so you don't force air into the living space. You want to draw the air in from the coolest side of the the house. I'm sure you know all that.

I don't know brands, but something a little bigger than Home Depot type stuff is better. Try Grainger or an industrial equipment vendor. I think you're near Phoenix, right...you should be able to find a big rack-mount fan you can attach to the wall.

[billt]

Bill you  are talking about an attic fan. A whole-house fan traditionally is a big fan set in the ceiling somewhere that draws cool air through the house, up and out through the attic area. That type of fan would definitely give you a small negative pressure causing wifely consternation at the dust levels.....

You're right. I got the name wrong. I need an attic fan, not a whole house fan that connects to the living space through louvers in the ceiling.

[PegLeg45]

Like Jay said, you can get more durable equipment through Grainger or McMaster-Carr......better bearings and longer lasting than box-store goods.

I spent a good many years working in an industrial facility and we had a LOT of fans... everything from roof-mounted exhaust fans to high flow combustion burners. I've installed and maintained a lot of fans.

Where you draw from is critical...just like in HVAC, air flow is limited by draw. The highest flow fan won't do squat if it can't draw from somewhere. Several vents under the eaves will do and would make a big difference.

As long as you stick with 120vac, wiring is easy. If you can wire a shop light, you can wire a fan.