Outside inline fan noise

G

gkay723

Active Member
I'm currently drawing air through the side of my building with one of these. Only problem is that it's making a whole lot of noise on the outside. Is there a way to reduce some of that noise?
 

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smokinrav

smokinrav

Well-Known Member
Secure your mounting, or get a better fan. Sorry, so simplistic, but true. High quality in-line fans should not make noise noticeable from the outside. Where are you exausting?
 
TheManicOrganicDK

TheManicOrganicDK

Well-Known Member
If possible, add an silencer, if not, change to a vent that can fit an silencer. This tiny silencer, do the trick for about 900 m3 being sucked out at full speed, no noise outside.
(I´m also drawing from outside/public.)

air-in+silence.JPG
 
Renfro

Renfro

Well-Known Member
gkay723 said:
I'm currently drawing air through the side of my building with one of these. Only problem is that it's making a whole lot of noise on the outside. Is there a way to reduce some of that noise?
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Thats an exhaust vent. You say you are drawing air through it (intake function)? If so then I assume you have removed the flapper door or screwed it open. Is the noise you hear the actual fan or is it the air moving through that vent?

I have 10 and 12 inch intakes using dust shrooms in my basement window wells. You can't hear any blower noise but I have about 10 or 12 feet of duct on the 10 inch and about 25 feet on the 12 inch. The duct is galvanized snap seam. The blower without the duct is loud as hell, with the duct it's super quiet.

So if you have the blower stuck right by the vent you should install some galvanized snap seam duct and make the run between the blower and the vent at least 10 feet. Do NOT use accordion duct, galvanized snap seam. If your intake is going to have really cold air in the winter you will want to put insulation around the outside of the duct and blower to prevent condensation on the outside of the duct dripping everywhere.
 
natureboygrower

natureboygrower

Well-Known Member
Renfro said:
Thats an exhaust vent. You say you are drawing air through it (intake function)? If so then I assume you have removed the flapper door or screwed it open. Is the noise you hear the actual fan or is it the air moving through that vent?

I have 10 and 12 inch intakes using dust shrooms in my basement window wells. You can't hear any blower noise but I have about 10 or 12 feet of duct on the 10 inch and about 25 feet on the 12 inch. The duct is galvanized snap seam. The blower without the duct is loud as hell, with the duct it's super quiet.

So if you have the blower stuck right by the vent you should install some galvanized snap seam duct and make the run between the blower and the vent at least 10 feet. Do NOT use accordion duct, galvanized snap seam. If your intake is going to have really cold air in the winter you will want to put insulation around the outside of the duct and blower to prevent condensation on the outside of the duct dripping everywhere.
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Nice to hear you have had positive results with those shroom filters. I've wondered how well they work. Must be good if youve had no issues pulling outside air through them. I worry about pm coming from outdoors so i never open windows near my spot. One of those filters would help.
 
Renfro

Renfro

Well-Known Member
natureboygrower said:
Nice to hear you have had positive results with those shroom filters. I've wondered how well they work. Must be good if youve had no issues pulling outside air through them. I worry about pm coming from outdoors so i never open windows near my spot. One of those filters would help.
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They are extremely effective and can be washed and reused. Nothing gets past them as they are oil coated.
 
Star Dog

Star Dog

Well-Known Member
Turning the fan speed down can have a big impact on the fan noise, ideally a variac but a plug in works effectively only with a bit of humming.
 
Renfro

Renfro

Well-Known Member
natureboygrower said:
How much of a strain do they create on the fans?
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A lot less than slinky duct. The smooth walls allow for laminar airflow.

You can get really close in performance using flex duct IF you install it straight using support and pull it out tightly so it's is smooth (the walls). If you get it to 0% compression (stretched all the way out tight) the difference is negligible when compared to galvanized. How long the flex duct lasts stretched hard like that? I suppose that depends on the quality of the duct and how it's supported. Flex duct often moves a little every time the blower kicks on or off. If it's rubbing somewhere it can cause abrasion that eventually results in a leak.

Here is a good writeup on the flex duct that shows some good static pressure numbers for different amounts of compression on the flex duct.

 
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