Looking to replace the current (old-school) whole house fan with a more quiet and reliable solution (e.g. a Quiet Cool. One thing I noticed is that my attic is leaking when running the current fan, pushing air and insulation back into the living area. Therefore I’m planning to vent the new fan not into the attic, but straight to the outside through the roof. In addition, I want to install an attic fan to blow stale air from the attic.
Now I’m left wondering, if the whole house fan runs 4,000+ CFM, what kind of vent should I install in the roof? I’m concerned if the vent does not allow for the CFM throughput, it will create a bottleneck and causing the fan to break down early. The diameter of the duct would be 18 inches. Any recommendations?