Question on whole house fan - in right forum? - http://www.hvacmechanic.com/ Forums
Original message
| pharmacist25
 |  "Question on whole house fan - in right forum?"
, posted Wed 16 Jul 12:22  
Sorry about the premature post.
I have a question regarding whole house fans but am not sure where I should post. Can someone help or point me in another direction if needed? I don't want to bother anyone if I am in the wrong venue.
Thanks
Questions:
1. I am beginning to understand that due to the house retaining heat that a lower CFM house fan actually dispels heat better than a much larger traditional one. If this is the case most of the lower ones are about 1600-1700 cfm. What would be the difference in me putting a regular 2200 cfm box fan in a window (aside from venting the attic) to one of these lower speed whole house fans?
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Replies:
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| Freon
| "Re(1):Question on whole house fan - in right " , posted Wed 16 Jul 14:11
It seems you are talking about an attic fan, not a whole house fan. The idea of an attic fan is to keep the attic cooler so the heat transfer into the house contiguous to the attic space is reduced. Less heat transfer into the house, less cooling is required and you save money.
The trade off is you're using electricity to run the attic fan. So the bigger the fan, the more expensive to run. Another concern is that for an attic to cool using an attic fan, there has to be air flow. Somewhere, usually sofit vents, there has to be air entering the attic. Be sure you have adequate air inflow to balance the rated cfm air outflow.
You might measure the volume of the attic. Then calculate the needed cfm so that that attic air is replaced say once an hour. Another thought... consider radiant energy. Reflective metal sheets can do wonders.
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| | pharmacist25
| "Re(2):Question on whole house fan - in right" , posted Wed 16 Jul 14:48
No. I was speaking about a whole house fan mounted in the upstairs ceiling, sucking air from outside into the house and blowing the exhaust out thru the attic gable vents/soffits/and ridge vent. My question is why can't I just put my 2200 cfm box fan in a window to suck that air into the house. My primary concern or desire is to suck fresh air into the house at night. Wouldn't this be the same (other than a whole house fan venting the attic) as placing a 1600 cfm whole house fan in the ceiling of my house and running that?
Thanks again
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| | Freon
| "Re(3):Question on whole house fan - in right" , posted Wed 16 Jul 15:39
Sorry I misunderstood you. You can put a window fan in and then cut a vent hole in the house ceiling so the air has a path into the attic and sofit/ridge vents and ultimately back to the outside. Just be sure you have a complete path... air in from outside, air out of the house back to the outside. The window is one access to outside air. But you'll need an air flow path to the attic. Also will the door to the room with the fan always be open at night?
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