quiet vents??

[siftedunity]

hi im trying to pull air in from a cool spare room, the sound is fairly quite.. but whenever I try to fit a vent over so it looks less conspicuous, it makes it really noisy all - you can hear is a whooshing sound whereas without the vent on its close to silent. ive searched everywhere and I cant find a lot of variation in vent design and have not found any designed specifically to be quieter.

does anyone have any ideas?

 

[anon0988]

Sounds like you need to slow the air speed down. Before I (or probably anyone) can give any real solid suggestions we'll need some more info. What are you using the air for (light cooling, room intake, etc)? Do you need as much air as you're taking through it? Also, what type of vent are we talking about? Is this a closeable floor vent, a cold air return vent, or whatever else? What size ducting are you using on the vent? What's your fan size and speed? Do you know if the fan has a certain CFM rating, and if so, what?

 

[siftedunity]

right the fan is large im not sure how much it moves but I will find out and update, its also rigged up to 6 inch ducting, a fan speed controller, and it cools two aircooled hps. at the current setting it is the quietest I can get it while still effectively cooling the hoods.

my aim if for this to be disguised as any normal air vent found around the home.. as long as it doesn't look out of place I will be happy. so it needs to be on a ceiling.

thanks for your reply

 

[anon0988]

So it sounds like you've already lowered your air speed as much as possible with the fan speed controller, that would have been my first step. Next I would say we need to look at the size of the fan. A 8-12" fan (oversized for the ducting, since you stated it was big) might possibly just be pulling too much air to be quiet. We'll know more about this once you post CFM ratings hopefully. If that's the problem, I'd say buy a smaller fan. You can pick up inline centrifugal 6" fans on amazon for around $80. If that's not an option, the final idea I would have would be maybe creating a muffler effect which could also possibly help slow the air down as well. For this you'd want some sort of breathable foam, like you might put on a mattress for extra cushion. You could put the directly behind the vent cover, possibly taped to it. The idea would be that it allows air through, but slows it down enough to quiet it. I don't know, seems like air speed is the problem if it's making a bunch of noise with the vent on. To me that says smaller fan or slow the air down through obstacles.

 

[Granger2]

Yes, more info. A larger fan with a speed controller lowering the speed will usually cut the noise down. Good Luck. -granger

 

[anon0988]

Yes, more info. A larger fan with a speed controller lowering the speed will usually cut the noise down. Good Luck. -granger

I think you may be misreading what he's stating is the issue. I think he's saying the duct cover on the ceiling makes a noise when on, but doesn't when it's off. That means it's a CFM issue most likely. If you get a bigger fan and run it at a lower speed, yes it will make less noise. But in this situation it isn't the fan noise that's the issue, it's the air flowing over the vent cover. The larger fan running at lower speed is still moving the same amount of air as a little fan running at full speed, so the air moving over the vent should make the same amount of noise. Now if he gets a smaller fan and runs it at a lower speed, he should be able to reduce the air speed enough to stop the noise at the vent cover. Sounds to me like a simple case of having your equipment over matching your environment.

 

[OhighO]

Increase the size of the vent if possible. This will allow the same or greater cfm but reduce velocity due to high static pressure.

 

[dank.frank]

slot diffuser.
single deflection industrial grille.



dank.Frank

 

[siftedunity]

I think you may be misreading what he's stating is the issue. I think he's saying the duct cover on the ceiling makes a noise when on, but doesn't when it's off. That means it's a CFM issue most likely. If you get a bigger fan and run it at a lower speed, yes it will make less noise. But in this situation it isn't the fan noise that's the issue, it's the air flowing over the vent cover. The larger fan running at lower speed is still moving the same amount of air as a little fan running at full speed, so the air moving over the vent should make the same amount of noise. Now if he gets a smaller fan and runs it at a lower speed, he should be able to reduce the air speed enough to stop the noise at the vent cover. Sounds to me like a simple case of having your equipment over matching your environment.

thanks,yes the fan is large about 12" with 6 in ducting. and its large but its airflow is perfect in hot weather on full wack. ive switched this down like I said and started running at night.. so yes the fan noise isn't the problem, its the sound of air whooshing through the grill.

 

[siftedunity]

Increase the size of the vent if possible. This will allow the same or greater cfm but reduce velocity due to high static pressure.

thanks for your response. this is what im looking for but im not sure which one will be most effective..

 

[siftedunity]

slot diffuser.
single deflection industrial grille.



dank.Frank

im not sure what this is but I will check it out. thanks for responding

 

[facedark]

thanks for your response. this is what im looking for but im not sure which one will be most effective..

OHighO is correct, using larger vents will eliminate your problem!