Stealth is the Word - Silencing exhaust fans

cobshopgrow · Dec 25, 2020

L84AD8 said:
Might be a hard one. I live in aus and dont have access to the meter - quick google doesnt show any aussie ones I can acces readily annoyingly enough

may check your amazon.com.au for plug power meter and you will find.

i dont know your fan, but it looks really small if its the small black box directly behind the filter.
i wouldnt go smaller then with 125mm ducting and fans ,even on small setups.

whats really important is to decouple the fan from pretty much anything.
mine are hanging in rubber, principally like its done with microphones to decouple them.

what i use to hang my fans, no direct contact to anything is important.
kill the vibrations right where they start.

absolute no noise problems since i use ec fans i can regulate from 0-170w.
2 tents running are in the range of a silent PC, at least in winter.
didnt even needed isolated ducting so far, while i have some at hand and this always helped big time when using hard to regulate AC fans.

lazaah · Dec 26, 2020

L84AD8 said:
Might be a hard one. I live in aus and dont have access to the meter - quick google doesnt show any aussie ones I can acces readily annoyingly enough

Bunnings and jaycar have them.

I used to grow in stealth setups, they were never silent so I generally had to mask some noise (e.g. fish tanks and terrariums with fans).

Noise comes from two sources, the fan and the air whooshing through the duct.

In my experience with moving to a larger area. I solved the first by buying a 6in mountain air silenced ec fan and hanging it with bungies, at 50% power the thing is genuinely super quiet and I can't hear the motor. Its also reduced the sound level of the blades within the ducting.

The most effective way to reduce the whooshing of the ducting is to increase the lengths of duct on each end of the fan and use cheap acoustic ducting. Try to reduce bends close to the intake and exhaust holes, they amplify the noise from within the duct majorly. Acoustic ducting will reduce the noise of bends from the outside, but not the internal noise created from the bend that exits the duct.

I would try putting together diy mufflers on the ends before purchasing a pre-made in line silencer. Silencers will only reduce the noise of the fan within the duct, and some of the whooshing noise if there is no bends after it.

In my previous situations the most effective thing I could do was to dampen the noise of the air leaving the duct by diffusing the exhaust with a bucket and soft packing. In my current situation I've reduced the issue by having a long intake duct and pushing through my carbon filter which dampens the noise. However, this means I've had to be diligent in ensuring there are no pinhole leaks between the fan and the filter.

If you want a photo of the muffler I used to use, just holla

L84AD8 · Dec 26, 2020

L84AD8 said:
ill give that a go. thanks mate

lazaah said:
Bunnings and jaycar have them.

I used to grow in stealth setups, they were never silent so I generally had to mask some noise (e.g. fish tanks and terrariums with fans).

Noise comes from two sources, the fan and the air whooshing through the duct.

In my experience with moving to a larger area. I solved the first by buying a 6in mountain air silenced ec fan and hanging it with bungies, at 50% power the thing is genuinely super quiet and I can't hear the motor. Its also reduced the sound level of the blades within the ducting.

The most effective way to reduce the whooshing of the ducting is to increase the lengths of duct on each end of the fan and use cheap acoustic ducting. Try to reduce bends close to the intake and exhaust holes, they amplify the noise from within the duct majorly. Acoustic ducting will reduce the noise of bends from the outside, but not the internal noise created from the bend that exits the duct.

I would try putting together diy mufflers on the ends before purchasing a pre-made in line silencer. Silencers will only reduce the noise of the fan within the duct, and some of the whooshing noise if there is no bends after it.

In my previous situations the most effective thing I could do was to dampen the noise of the air leaving the duct by diffusing the exhaust with a bucket and soft packing. In my current situation I've reduced the issue by having a long intake duct and pushing through my carbon filter which dampens the noise. However, this means I've had to be diligent in ensuring there are no pinhole leaks between the fan and the filter.

If you want a photo of the muffler I used to use, just holla

That's gold. Thanks mate

My EC fan is actually brilliant its in a built in silencer so really the only thing im dealing with is the whoosh which is pretty major. You pointed it out and which may be my problem. I've had to suspend my fan/silencer and filter along different sides of the wall interally which in turn has introduced several elbows - 1 from filter to intake - 1 from fan to outtake and a 3rd bending upwards to vent through the ceiling. Im guessing thats where majority of the noise is coming from.

with your bucket and soft packing idea. Do you think having a 2nd filter at the end of the ducting would work similar? so that the setup would look like this

(intake) Filter > Elbow Duct/join > EC Fan > Elbow Duct/join > Duct through Ceiling > 2nd Filter
I'll try and look at my options with reducing joins and elbows but in abit

MICHI-CAN · Dec 26, 2020

Extend the vent tube to a greater distance from ceiling opening. End is source of noise, vibrations. Vibrations will be amplified by the dry wall below.

Super glue a drywall nail to a speaker. Screw it into dry wall. Hook up and turn on. Wall amplifies low decibels. Peace and quiet.

lazaah · Dec 27, 2020

L84AD8 said:
That's gold. Thanks mate

My EC fan is actually brilliant its in a built in silencer so really the only thing im dealing with is the whoosh which is pretty major. You pointed it out and which may be my problem. I've had to suspend my fan/silencer and filter along different sides of the wall interally which in turn has introduced several elbows - 1 from filter to intake - 1 from fan to outtake and a 3rd bending upwards to vent through the ceiling. Im guessing thats where majority of the noise is coming from.

with your bucket and soft packing idea. Do you think having a 2nd filter at the end of the ducting would work similar? so that the setup would look like this

(intake) Filter > Elbow Duct/join > EC Fan > Elbow Duct/join > Duct through Ceiling > 2nd Filter
I'll try and look at my options with reducing joins and elbows but in abit

Try the bucket before buying a filter, it'll be much cheaper. It may even work better as if you put materials of mixed density (e.g. polyfil, chunks of old tires etc) it'll absorb a greater range of vibration. A bucket also offers a greater volume of sound deadening material than a filter

MedicinalMyA$$ · Dec 27, 2020

I got rid of the whoosh sound by using oversized ducting and lining the inside with some egg-crate type foam that was sold as a bed-liner/topper portable camping mat type thing. Previously I wrapped it in carpet and had long runs either side of the fan worked well but yes oversizing the fan and running it slower has worked the best for me as long as the can isn't directly attached to the fan.

L84AD8 · Jan 1, 2021

thanks for the suggestions everyone really appreciate it! ended up buying some acoustic ducting and added an insulated/ ceiling with some R1.5 wool

Running the 6" at 20% which is all I need for my space and barely a hum. Cheering!

Cotton Candy up first

Stealth is the Word - Silencing exhaust fans

cobshopgrow

Well-Known Member

lazaah

Well-Known Member

L84AD8

Member

MICHI-CAN

Well-Known Member

lazaah

Well-Known Member

MedicinalMyA$$

Well-Known Member

L84AD8

Member

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