Acoustic Liner inside ducts connected to fan coil units
Acoustic Liner inside ducts connected to fan coil units
(OP)
The specs call for acoustic liner for 3 meters of duct connected to equipment. Applying acoustic liner internally in the small sizes of duct that are within 3 meters of fan coil units is not convenient. Can sound be attenuated by applying the acoustic insulation on the outside of the ducts given that there is already thermal insulation on the outside of the ducts ?





RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
Sound attenuating coatings applied to the outside of a garbage chute is meant to reduce the impact noise and sliding/rattling noises from objects travelling down inside the chute-a completely different type of noise generated compared to a fan-coil air noise situation.
If the specifications call for acoustic lining, then there must be a darn good reason for it.
RE: Acoustic Liner inside ducts connected to fan coil units
If you need to keep the cross section of the duct, increase the size by the thickness of the liner.
If you leave that duct smooth on the inside, you will hear every squeak and rustle off that fan, just like you were using an ear trumpet.
B.E.
RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
Shifting it out a few feet may allow noise to be radiated from that part of the duct, with the effect as discussed above.
Generally, this treatment is typical of noise sensitive specifications, and I wouldn't consider the specification to be over and above.
Further to Berkshires comment above - any normal spec will define the duct size indicated on the drawings as clear internal dimensions, so liner adds to overall dims.
RE: Acoustic Liner inside ducts connected to fan coil units
Strangely, the other offices downstream of this office did not have the noise problem, which implied to us that, if you have enough twists and turns in the ductwork, the noise problem abates on its own. Any others out there with similar experiences?
RE: Acoustic Liner inside ducts connected to fan coil units
I have to say, trying to not do something as designed and bid on because it is not convenient or easy would be unacceptable to me as the EOR. If you do go back looking for alternates, at least offer some other method for consideration. I like these for sound attenuation: h
Of course, by the time you get these accepted on a performance basis and get the quote from Ruskin... you'll be out some bucks (and time).
PS: just re-read this and I sound like an old man. Swear to god I'm in my mid 30s!
www.ellisconsultingengineers.com
RE: Acoustic Liner inside ducts connected to fan coil units
If I did not know better, I would think that mechanical3010 already has these ducts installed without the liner, and is trying to find a way out of the situation he has gotten himself into.
B.E.
RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
There are branches from the main duct at 90 degrees to the mains. These branch connections are not by means of elbows but by 45 degree entry. In these branches are VCDs and then the flexible duct that connects to an acoustically lined plenum box that houses the diffuser.
RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
RE: Acoustic Liner inside ducts connected to fan coil units
Also check the fan, can the fan speed be reduced? Ensure the index run is 100% open and the air flow is not being throttled using balancing dampers.
RE: Acoustic Liner inside ducts connected to fan coil units
Furthermore, is it very important or effective in attenuating sound to line the ducted return to the Air Handling Units?
Thanks