Quote Originally Posted by houdini
Thanks a lot folks for your kind replies. I appreciate the noise INSIDE is a consideration which I can deal with. My biggest concern is the roar of the air as it exits the window. Will a silencer on the o/p of a 1500 cfm fan reduce this so that folk behind windows 30 feet away will not be curious (or pissed off !).
I have the same problem but i solved it i have a furnace blower hooked up 2 my carbon air filter that exits the room im using dryer flex tube than attach 4" PVC piping i cut a 2 liter pop bottle in half and stuck this over 4 " PVC pipe with this its reduced 2 like 1 " this works awesome very very quiet noise reduction what size is ur piping ur u using look at my pics to see i have a small room so if ur using bigger piping u need to reduce the end pipe as small as u can