Ventilation for whole house fan.


  #1  
Old 11-06-14, 01:05 PM
L
Member
Thread Starter
Join Date: Nov 2014
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
Ventilation for whole house fan.

We purchased a quiet cool 6400 whole house fan. It moves just over 6400 CFM with both fans running and about 3200 CFM if we only run one fan. We had five dormers that would equal about 3.47 ft.² net free ventilation. The fan distributor/installer was also a roofer so he installed O'Hagan vents on our S style concrete roof. He only installed four that equal about 2.7 ft.² net free space. So, that only totals 6.17 ft.² The fan calls for 8.5 ft.² of ventilation.
He swore that it would be fine. Well, we can feel the air coming back out of the light switches and electrical outlets. I figured that we did not have enough ventilation so I only put one fan on. One fan should only need less than 4.5ft.² of ventilation which we have more. But, even with only one fan running, We still feel the air through the outlets.
I would guess the attic square footage is around 1000 or 1100 ft.²
Our house is 2262 ft.² with 9ft ceilings.
I don't get it. Any insight?
 
  #2  
Old 11-06-14, 01:09 PM
L
Member
Thread Starter
Join Date: Nov 2014
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
Oh, and the dormers are higher in the attic and the O'Hagan vents he added are lower. Technically, aren't lower ones supposed to be intake and upper vents are exhaust? When the whole house fan is pressurizing the attic, does it matter where the vents are located?
 
  #3  
Old 11-06-14, 02:36 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 9,460
Received 47 Upvotes on 43 Posts
Doing a little math, 2,260 sq ft with 9" ceilings would be 20,000 ft³. Divide that by the 6,400 cfm and, if all moved as advertised you would be exchanging all of the air inside your home every 3 minutes.

A note before I go on, there cannot be any open combustion appliances like a furnace of water heater in this house. Explanation if needed.

Increasing the ventilation area will actually increase the total air flow which includes the replacement air filtering in through your walls. Although some of what you feel can be attic air looking for a place to go the majority is outside air pushing through every path possible.

There are drawbacks to whole house fans, like pulling humid air into your walls, but if your desire is to cool the house with outside air when the ac is not in use (or you don't have ac) just how much fresh air did you want. 20 air changes per hour seems a little over the top.

Bud
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: