I'm thinking of adding a simple air return system using one of these in-line Panasonic whisper fans: http://www.rewci.com/panwhisvenfa.html My house is 2100 sqft, 1 story, with the stove in one corner and the master bedroom on the opposite corner. I'm planning to install the fan and ducts in the attic, cutting vent holes in the ceilings of the master bedroom and the living room (where the stove is). I need help in determine the following: 1. Will a 120 cfm be enough? I like it for its low power and low noise (most likely this fan will be continuously on through out the winter). 2. I'm eyeing those flexible ducts with insulation from Home Depot. They seem to be the most easy installation, compared to the rigid pipe. Plus with the pipe, I'd have to install some kind of insulation around it. I want to minimize the time I need spend in the attic for installation. Do you see any problem with this? Basically the 2 fans I'm looking at: 120 cfm = 36W, 1.0 sones, 4" diameter duct 240 cfm = 57W, 1.4 sones, 6" diameter duct I'd appreciate any help I can get. Thanks!