DIY Whole House Fan

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Old 04-27-17, 06:37 AM
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DIY Whole House Fan

I've come to run outta projects and going to start this one. I've seen a youtube video of a guy who put together a couple gable fans (1600 cfm) and the proper ducting, probably for around $400. There is a larger professional fan that puts out 3013 cfm by Quiet Cool. My house is a ranch with an upstairs bonus room. About 2100' down and 800' up. Ceiling height 9'. I do not want to install the intake vent on the ceiling, rather on a wall, maybe 7' up. I don't need the breeze effect so I'm thinking the 1 fan will be plenty for air draw. I have plenty enough feet of ridge vents and soffit vents. Plan to run this off a remote control as to keep from having to climb the stairs to operate. Should be able to do this for uner $500. Any thoughts or opinions? Thx DM
(I did have another older thread regarding a particular brand of wholehouse fan, which I am no longer interested in. Best to start a new one)
 
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Old 04-27-17, 07:27 AM
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I've come to run outta projects
is that even possible???


Don't see why you couldn't do it that way. They do sell whole house fans that have the fan at the far end (or in the middle) of a big duct, and I imagine they can be a little quieter.

You want the duct big enough so the air velocity isn't so high that you get a lot of "whooshing" noise. In Indiana you need to think about how you will seal and insulate the inlet during the winter or you will lose a lot of heat even without the fan running. And the duct itself should be air sealed and probably insulated so there is no chance of condensation on cool nights.

I would choose the quietest fan I could; purpose built attic fans are designed for low noise, gable fans not so much.
 
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Old 04-27-17, 07:40 AM
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This fan is 16". I'll get an insulated flex duct that big. They make an inline ck valve that when running will overpower the flapper to let the air through, then has a rubber seal on spring loaded door when off. They make a magnetic plate that goes over the vent when not in use, IE winter season. Not concerned about that part of it, otherwise. I'd have the fan installed approx. 10' from living space wall so shouldn't here it operating. They do make this similar setup, for about $1000 or so. If I can save a couple hundred, I will! Just unsure that the fan I described would be big enough for an air-draw.
 
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Old 04-27-17, 09:25 AM
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The fan you have is the 3000 cfm unit? Usual recommendation is 1.5 to 3.0 cfm per square foot of floor space; you are at about 1.0 I think it will still do the job; may just take a little longer.

Key to getting best performance from a whole house fan is to choose which windows you open carefully to get even and best cooling effect. A little experimentation will let you figure that out.

It's a bit of a pain to walk around opening windows every time you want to use the fan and closing them in the morning, but necessary for effective use.
 
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Old 04-27-17, 09:38 AM
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I don't have any fan...yet, but would most likely be a 3000 cfm. I'd go larger if I could find one. Not interested in installing 2, with a larger cut out in the wall. Don't mind opening windows. Part of the game!
 
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Old 04-27-17, 01:39 PM
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One rik involves your type of heating and how you heat hot water. Any naturally drafted appliances will be seriously back drafted under the pressures created by a fan that large, even with windows open. If you have electric or sealed combustion water heater and furnace/boiler (or a heat pump) you may be fine. Let us know and I will explain further.

Bud
 
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Old 04-27-17, 02:06 PM
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Gas heat & water heater, both units sitting in garage. This fan is actually a bit undersized for my sq footage. Fan ordered. Getting the rest of the stuff over the weekend
 
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Old 04-27-17, 02:28 PM
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"Gas heat & water heater, both units sitting in garage." That can work as long as the fan doesn't depressurize the garage, like someone leaves the house to garage door open. Enough said, I do like the the whole house fans and the benefits of that nice cool air.

best
Bud
 
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Old 04-27-17, 02:56 PM
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Thx Bud. Yeah, I see the issue. May only effect the water heater. Normally when we go out to garage, the exterior doors are closed. So we open the interior, close it, then open and exterior. I have a CO detector out near this area, as well. Thank you for pointing this out!!
 
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Old 04-28-17, 07:36 AM
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Question...so my fan will be 16". I walk studs are 16" on center. I wish to not have to cut 2 studs for this duct so I either need to fabricate something out of wood, just behind the studs in the attic, to receive the backdraft valve and then continue with the flex duct to fan, or just come outta the wall with a 14" valve and then a reducer up to the 16" size of pipe. I want the size to stay 16" for most of the length to keep the volume of air up. Wanted to keep down the total amount of fittings in the run, and the cost. Looking for some advice
 
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Old 04-28-17, 09:34 AM
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If you want the least obstruction, then you would be better off using the 16" backdraft damper. If you just sister a couple of 2x6s to the existing studs, on the outside faces, and mount a pieces of plywood to them, that should give you enough extra room for the damper. Then use a couple of notched 2x6 pieces to seal the top and bottom edges and you are all set. Only a little more work than using the smaller damper.
 
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Old 04-28-17, 10:34 AM
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Ok. Yeah that sounds good. Any opinion on a remote control electric socket? Plan is to mount an elect socket in the attic, and plug say, a power strip into that, which can be control my a little remote. Signal probably only have to travel maybe 40' tops, but needs to go through sheetrock. Maybe an RF remote type. Guess I'll look around.
 
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Old 05-25-17, 05:51 AM
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I'm all set with all the material. Quick question...the best place for me to put this in the wall, is directly below a cold air return. I was advised by the people who represent the fan I purchased, that as a rule of thumb, to keep this vent I'm installing at least 3' away from cold air return. I see no reason to do this, as whether my vent is installed directly below it, or 70' away from it, my fan will create a negative pressure. My hvac ducting is not connected to the crawl space, or garage, so it is sell contained anyway. Am I missing something? I wont be running the heat or air while my WHF is operating, so I'm going to chalk this up as simply..."their rule of thumb".
 
 

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