Duct silencer type

Hi, do anyone have experience with duct silencer - im thinking about adding second one to my system. My current one is as AC infinity, Phresh type with egg crate pattern foam inside - i dont find to be soundproofing very much, as i know from my musical background the foam dont soundproof but dissipates sound waves so i think ill be better choosing one with rock/fiberwool inside. I was thinking about even oversizing it to 8” instead of 6 cause as far as i know it wont change airflow - it ll only reduce speed of air movement. If ill have two silencers the foam one i would use beetwen carbon filter and fan, cause i find more sound traveling on the exhaust side. What are your thoughts ?

I used to DIY with some house insulation (think pink panther), a tote, and some chicken wire.

Lay the chicken wire or whatever supportive mesh you have on hand, out flat. Then lay the insulation on top and roll it up like a carpet around an exhaust pipe or something that size, to make sure you can insert your exhaust once roll is installed into the tote.

Once the roll is the size it will fit snug in the tote, cut out the short side of the tote large enough to feed the exhaust pipe into the tote and rolled up insulation wire roll.

Install the roll in the tote and feed the exhaust pipe in 3/4 of thru the tote into the roll.

Pack the rest of the tote tightly with insulation and duct tape it sealed, especially around the exhaust pipe entering the tote side.

Drill holes all around the tote to let the proper amount of air escape when fan is on. LOTS of SMALL holes.

This should quiet down your exhaust system considerably.

024matters said:

Hi, do anyone have experience with duct silencer - im thinking about adding second one to my system. My current one is as AC infinity, Phresh type with egg crate pattern foam inside - i dont find to be soundproofing very much, as i know from my musical background the foam dont soundproof but dissipates sound waves so i think ill be better choosing one with rock/fiberwool inside. I was thinking about even oversizing it to 8” instead of 6 cause as far as i know it wont change airflow - it ll only reduce speed of air movement. If ill have two silencers the foam one i would use beetwen carbon filter and fan, cause i find more sound traveling on the exhaust side. What are your thoughts ?

Click to expand...

the design of the ACI silencer is similar to that of a 'rain cover' I used to make for paintball markers.
select PVC of the appropriate diameter, cut to length (ACI seems to go 3x the diameter), and fire up the Dremel - rather than multiple holes, I would cut long slots: as big as possible while leaving enough PVC to provide strength/structure as you'll be wrapping multiple cloth diapers around this PVC skeleton; then, around the diapers wrap some sort of semi-stiff material (a correctly-sized poster tube would be perfect) and use some screw clamps to hold it all in place.
I would agree with assessment re: foam/waves - hence the use of cloth diapers

Im considering if it will be better to have two short (30cm) silencers after and before fan or one long (60cm) on the end as carbon filter and exhaust side are located in home

I use a Phat Muffler and just recently added the ACI Silencer. The phat muffler looks like a carbon filter inside and don’t have the egg crate foam like the rest. The Phat Muffler does reduce sound around 50% and I say the ACI Silencer reduce sound around 25%. Phat Muffler have 2 styles one is a shorty and one is regular length. I have experience with the regular length one I like it.

I ran my system one day without the Phat Muffler and it was so freaking loud after hearing with the Phat Muffler, I instantly realized how much it lowered the wind noise. Now I use the Phat Muffler on intake of extraction fan before filter and the ACI Silencer after the fan.

Now it doesn’t make it absolutely silent but it softened the sound of the wind noise makes things more tolerable.

Good info thx, phat seems to be classic wool inside ! Do you hear the difference in sound around carbon filter after you added one after it ? As i found out from silencer (wool insulation type) company data sheet there is no much difference in pressure loss beetwen 30 cm and 50 cm length, but there is a 3 db change. Two shorter silencers would soundproof even as much as twice as one but there will be 2x pressure loss so much more cfm needed. So its a trade off, i dont know how much fan sound comes through carbon filter but i think its better to have longer one on the end of the system as there is more room there for sound to escape. I become HVAC freak after reading so much

I thought about buy a wind tool to measure it lol but I just went off ear. So when I only had the Muffler I tried it on booth ends of fan to see which sound better. I choose to put it between the carbon filter and fan because it reduced the sound of wind being sucked in thru filter. It’s seems to me that it softens the wind pressure but it’s moving only slightly less wind as you stated. The manufacturer says it works best after the fan like you intend to use. Let me know how you like it when you get it set.

On a side note when I only had the muffler between the carbon filter and fan running fan on highest speed I heard nothing coming out the exhaust on the outside. Maybe if you can find the space try both between fan can carbon filter you may become silent lol

The one i bought with glasswool insulation 50cm long is much better than egg crate pattern foam one. As i researched rockwool is even better cause can muffle better low frequencies (9 db for 125 hZ instead of glasswool 7db) that are most important as they are that gets through walls etc most. Two duct silencers on two sides will double airflow loss, but yeah - carbon filter is transfering a lot of sound also. Ill use short piece of acoustic ducting as it works as silencer - but not as much muffling. As i found out AC infinity is vibarting a lot so there is some work to attach everything in a way to not let those transfer to another componets of the system. Im sharing my experience and knowledge from research for future generations. Peace

To clarify - when i mentioned two silencers will double airflow loss i was reffering to using two 30cm vs one 60cm

Modern Selections said:

I used to DIY with some house insulation (think pink panther), a tote, and some chicken wire.

Lay the chicken wire or whatever supportive mesh you have on hand, out flat. Then lay the insulation on top and roll it up like a carpet around an exhaust pipe or something that size, to make sure you can insert your exhaust once roll is installed into the tote.

Once the roll is the size it will fit snug in the tote, cut out the short side of the tote large enough to feed the exhaust pipe into the tote and rolled up insulation wire roll.

Install the roll in the tote and feed the exhaust pipe in 3/4 of thru the tote into the roll.

Pack the rest of the tote tightly with insulation and duct tape it sealed, especially around the exhaust pipe entering the tote side.

Drill holes all around the tote to let the proper amount of air escape when fan is on. LOTS of SMALL holes.

This should quiet down your exhaust system considerably.

Click to expand...

This could also be done as an inline silencer with a duct at each end.