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 exhaust ducting. Does anybody have experience of using large centrifugal fans in a similar setup ? Minimizing noise is really important. I'm aware of all the things to reduce noise such as sono-ducting, air silencers, etc. however I would hate to have a knock on my door from a neighbor asking why I'm running a jet engine in my room ! BTW I haven't actually heard a 1500 cfm fan running so I hope somebody here can tell me I'm being paranoid :D

my friends set up has an inline silencer on his ducting, it is quite bulky....
looks kinda like a big version of a baffle box that you would find on a car exhaust, but its made specificly for ducting.

same principal i guess

i would think if your hydro shop cant help you out, you would have to look at industrial air/con suppliers but there are solutions out there.
if you could figure out how they are constructed, im sure you could make a home-brew one without too much hastle.

hope thats of some help

ive just done some calculations, my fans 125m3 per HOUR, which ive worked out is 147cfm

shit thats a big ass fan...do you really need one that big? whats your set up?

p.s. i dont think it will sound quite as bad as a jet engine, more like a single engine cessna, the drug smugglers aircraft of coice....lol

centrifugal fans are very quiet. it's there biggest benefit.
you can also hand the fan by bungees which will absorb the vibrations

I find using plastic ducts absorb a lot of sound. I sleep in the same room as my grow so
I would know. The aluminum ones make the most noise.

You can also considering blasting metallic when ever the fan is on.
Your neighbors will be so distracted by that, they wont care about fan noises

yeah, you can build a box to put the fan in. It would help. You will have to somthing about that noise. I run a 449CFM centri. fan and you can hear it through a bedroom door. I would hang my 1500cfm fan in box

what harris said about the radio is a great idea, you wouldn';t have to blast, just loud to blend with the purrrrr of the fan

Also hanging blankets inside the grow room on the walls will absorb a ton of noise! Best of luck

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 !).

If noise is of serious concern make sure you do not make any reductions in the exhaust, in fact if you can start expanding the size of the exhaust as soon as it leaves the fan. This way you are actually lessening the restriction and giving the air more room to disperse and not less thus creating less pressure. More pressure and restriction mean more noise. What about splitting off the exhaust to two locations instead of one if possible.

Tryna