4" Blower Fan Super Loud

Im looking for a way to quiet my 4" inch blower fan down? or find out why its so loud in the first place. Im in a sealed room venting from outside to outside the Inlet is 4" ducting to the 4" fan- then the cooltube which is 6", through the tube and out 6" ducting out of the room......So 4" inch in 6" inch out. would that cause excessive noise?? when the fan is diconnected but on its not loud at all? Any advice or help would be much appreciated? Thanks Again Kronik

Anybody know about cfm? Pressure? Resistance? Duct size,etc

i have my fan on a bungee cord hanging from the ceiling so it dosent rattle, really would forget its on if I didnt smell it working.

Mine is hanging already No rattle, just Sounds like an airboat? 4" ducting into the fan the fan is into the 6" inch cool tube and out 6" ducting

heres how things are connected just thought it might help with some advice.....its loud through the ducting and out side the room.....

hey K, could well be the way that fan is charging the air right towards the twist in the pipe. The size difference in fans wouldnt create noise but they have to be ratiod like that to create the negative vaccume. If I was to guess as long as the fans don't create a rattle I would assume your getting wind noise from resistance somewhere.CMF I think is air flow per-minute. Idealy I believe your fans should be capable of changing the air every three minutes. To work it out you have to find out the area of your space, once you have that area you would multiply it by three (x3) and look for a fan with a CMF that would clear that space every minute. Although it would be advisably to get bigger fans than required and run them on a low speed to give adaquate preformance with reduced noise levels.

My light is on it own closed loop I don't exchange air with the outside....soon I understand the noise from resistance but where ? Right if you look at the pictures I'm pushing air through the light..... should I be pulling from the otherwise....or could it be the 4" to 6"?

Im no expert at all but I think it may be like someone said above (i think) that it could be from where the air hits the turn after the light and it starts swirling around and it hits that wall of the duct. try raising the light and having the duct straight(er) and see if it helps at all. dont keep the light there though obviously

I want my light as close as possible.....why would I move it away! I'll deal with the sound if that's the best suggestion?

CFM = Cubic feet per Minute , Ok so what you are trying to do is Exhaust... these fans are made to exhaust not push , So what you call your outlet there is where the fan should be mounted , you should alway mount a Exhaust fan 2 to 3ft from your termination point and also a BIG FYI any time you use a 90 deg turn (elbow) with moving air weather exhaust or Supply its like adding eqivlent to 40ft of straight duct . every turn you make dimminishes the efficentcy of your Fan/blower.

Bro just looked at those pics let me help you out , first off Im gonna need info, like were is that air going, the exhaust fan what diameter is it, and I can help you out 30yr HVAC exp. YA def got me LOL

I have a suggestion... you may not like it but it should decrease the noise by a lot. Get that fan off the light like the other guy suggested. Splice the duct somewhere halfway from shroud to ceiling and install the fan inside a slightly larger cardboard box stuffed with soft blanket/towel anything that will dampen the noise. Suspend it with bungee cord. Just having it directly away from the 90 will be better off. Those fans are self-cooled so do not worry, no over heating will occur. The thing is exhaust fans=airport runway sounds. It's just the life of a grower dude. Not much you can do. ~ BCbuddy420