damm thats a big rig lol

cant really give advice, but the replies to this thread have given me a few ideas...

with somthing that size i would think you need to tackle the problem from a few angles...

the noise crated by the fan itself
dynamat is an exellent suggestion, used on the fan unit itself and/or any nearby hard surface to damp down the noise.

vibration from fan mountings/fixtures
rubber fixtures like bike tyres sound a great idea, also use rubber gaskets where any hard joints are made (screws/bolts) to isolate any vibrations as much as you can

exhaust exit and intake noise(air noise)

making the intake exit diameter smaller will indeed strain the fan bearings, maybe a sleved duct will help,if you have a 12 duct, fit a 13" duct over the top of it for some insulation and maybe fill the gap with pillow stuffing or some kind of spray-foam, although i think it dries hard so not too practical for mooving the duct around.

if you can vent into a wall cavity or loft space rather than directly outside it will also act as an acoustic barrier. a loft space full loft insulation will damp the noise down nicely, you could even line the apex of the roof as well as the loft floor.

thats about all i can thinkof lol
babystarbud Reviewed by babystarbud on . air noise question I'm in the process of moving my growroom. We have a good location for the new one, the only problem is the proximity of a couple of open windows (on warm days) about 30 feet from the growroom. My question is concerning exhaust air noise. I'm going to be using a 1500 cfm fan to exhaust warm air through a window opening. The actual window frame itself is going to be boarded up and I'm making a wood box to surround the open window portion. The wood box will have a 12 inch hole cut in it to mount Rating: 5