# Whole House Fan (Ceiling Mount)



## knowshorts (Jan 9, 2009)

Total square footage (all living areas) times 3. You also need to consider the amount a square footage you have for attic exhaust. This amount will limit the size of fan you need.


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## Magnettica (Jan 23, 2007)

So 25 x 50 basement, 25 x 50 first floor, and 25 x 50 second floor?

Or 25 x 50 x 3 = 3,750

So 3,750 CFM is what I'll need to do this appropriately? 

Thanks.

This house had a ton of remodeling done recently and to be honest it all looked like crap, especially some of the wiring in the attic space. Poorly located smoke/ carbon detectors, cable television plates missing, spaghetti wiring in the unfinished basement, recessed lights in the kitchen that look like crap as far as spacing, uneven countertop receptacles, etc.


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## paul d. (Jul 13, 2008)

mag, get the $$$$$$$ !!


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## KayJay (Jan 20, 2008)

Whole house fan in NJ? I hope they don’t mind pissing their money away on winter heating bills, as even the louvered ones are still basically just a hole in the ceiling.


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## MDShunk (Jan 7, 2007)

Mag, make sure you can actually exhaust that much though the vents in teh attic. That's the biggest obstacle. About 75% of my whole house fan installs I have to add more square feet of roof, gable, or soffet vent. You will not get the rated CFM's if you can't push it out of the attic. It has to go somewhere.


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## knowshorts (Jan 9, 2009)

Mag,

1250 per floor x 3 floors x multiplier of 3 = 11250. So according to math you need a CFM of 11250. The amount of exhaust is even more important. But that is a big ass hole in your roof, so it aint gonna happen. It does take some time cool the attic from 130 degrees to 100, but mine draws in a nice breeze from the outside. Check out this link and click on a model for more information. http://www.rewci.com/wholehousefans.html



> Whole house fan in NJ? I hope they don’t mind pissing their money away on winter heating bills, as even the louvered ones are still basically just a hole in the ceiling.


The Tamaracks are fully insulated when not in use.


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## B4T (Feb 10, 2009)

I always try to install my fans in the gable end.. if there is one.

I also put a 30" shutter in the hallway to vent the house


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## Dennis Alwon (May 9, 2009)

Black4Truck said:


> I always try to install my fans in the gable end.. if there is one.
> 
> I also put a 30" shutter in the hallway to vent the house


A gable end fan and a whole house fan are very different. 

Are you saying you duct the whole house fan to the shutter opening?


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## MDShunk (Jan 7, 2007)

The CFM rating does not need to match the house's square footage by any means. Cubic Feet per Minute does not mean that you need to move every cubic foot of air in the house EVERY minute. Almost anything will work. The bigger one's tend to be a lot noisier. I installed a pretty big one in a home at the owner's insistance, and it felt like gail force winds breezing through the house when you had it on high and had the windows open.


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## Richard Rowe (May 25, 2009)

I have heard that if you put a variable speed control on the fan it's a big plus being able to control air flow better. My inlaws had one house that had a whole house fan.. they had a fireplace and turned the fan on with a fire. Bad move.


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## Magnettica (Jan 23, 2007)

MDShunk said:


> Mag, make sure you can actually exhaust that much though the vents in teh attic. That's the biggest obstacle. About 75% of my whole house fan installs I have to add more square feet of roof, gable, or soffet vent. You will not get the rated CFM's if you can't push it out of the attic. It has to go somewhere.



The attic has a roof-mounted exhaust fan, and gable vents on either side. 

This is what I bought and I got the job. Finally. 



> http://www.grainger.com/Grainger/items/3C545
> 
> Whole House Fan, Direct-drive, 2 Speed, Propeller Dia 24 In, CFM High 4500, CFM Low 3200, HP 1/5, Fan RPM 775/600, Voltage 120, 60 Hz, Single Phase, Amps 3.4/2.8, Height 7 In, Width 27 1/2 In, Depth 27 1/2 In, Ceiling Mounting Location, Includes 2-speed Pull Chain Switch and White Shutter


I am also ditching the pullchain and installing a two-speed switch.


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## knowshorts (Jan 9, 2009)

Mag,

Make sure you get an r-22 cover. When the fan is not in use, AC and heat (in winter) will get in the attic if not sealed.


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## Peter12 (Aug 5, 2009)

*Air Changes Per Hour*

The volume of the space you want to ventilate and the number of air changes per hour you decide you need will determine whole house fan CFM. I like to use 10 air changes per hour, so the fan has the capacity to exchange all the air in the living space of the home every 6 minutes. 

The fan CFM will determine how much free area you need in your attic to allow air being pushed into the attic by the fan to escape.

Not opening enough windows for intake and/or not having enough soffit, gable, or roof vents for exhaust in the attic will constrict airflow and reduce fan performance.

This whole house fan sizer makes it easy, figuring out required cfm and required free outlet attic area for you: http://www.whole-house-fan-info.com/whole-house-fan-sizer.php


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## pretygirl (Aug 10, 2009)

I was registered at your forum. I have printed the test message. Do not delete, please. 



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## Magnettica (Jan 23, 2007)

Peter12 said:


> The volume of the space you want to ventilate and the number of air changes per hour you decide you need will determine whole house fan CFM. I like to use 10 air changes per hour, so the fan has the capacity to exchange all the air in the living space of the home every 6 minutes.
> 
> The fan CFM will determine how much free area you need in your attic to allow air being pushed into the attic by the fan to escape.
> 
> ...


Hey, that was nice. I put the dimensions into the calculator and came up with 4167 CFM required. Well, that's just great because I installed the fan last week and it had a max CFM of 4500 and a minimum of I think 3700 CFM. I would have to say I sized it pretty well. 

Thanks for that link, that was great. :thumbsup:


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