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I’m looking for suggestions to reduce the noise caused by metal ductwork expanding and contracting during the heating/cooling cyle. Is it better to secure the pipe to the strap that it hangs from or to leave them disconnected ? Other suggestions I’ve had are heating the area the pipe is in to reduce the heat differential (ie, heat the basement) and secure it with more screws.
Any ideas ?
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I believe that the noise comes from the snap lock joints in the ductwork, not from the hangers or anything external. To minimize doct noise in my house I have done the following. Put a bead of silicone in all of the snap-lock joints. Wrapped all buried ductwork with reflectix (foil faced bubble wrap). Packed the stud bays with fiberglss (doing this in the whole house). Not running ducts in exterior walls. Also laid out runs so that one end is more or less "free" to float during expansion and contraction. I don't believe it is possible to completely eliminate this noise inexpensively, but you can dampen it right out for not much money. Use very few snap locks. I don't know if screws through the snap-locks helps or not. Longest run in our house ticks, but it is barely audible - usually worst in the morning on initial heat-up. My parents ten year old house has EVERY supply duct in an exterior wall. Their ducts wake me up in the night when we stay there!
Scrap foam rubber from work (black 1/2" very heavy) glued to the outside of the trunks in the basement has stopped must of the furnace noise (condensing furnace with combustion blower)
-Rob
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Before finshing the lower level on my last house I replaced all the 6" round sheet metal duct branches with the 6" insulated flexible. Boy! what a difference in the wind noise... Yes, there
was a little more pressure on the blower motor, but with proper support (keep sagging to a minimim. This should not be a problem. This house was heat pump so had low duct temp (no ticking/expansion). Current house is gas heat w/140 degree F air in
main trunk. I have duct noise (ticking, etc.) and plan on replacing sheet metal branches as before. Can't do anything about ducts between 1st and 2nd floor.
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I'm looking for suggestions to reduce the noise caused by metal ductwork expanding and contracting during the heating/cooling cyle. Is it better to secure the pipe to the strap that it hangs from or to leave them disconnected ? Other suggestions I've had are heating the area the pipe is in to reduce the heat differential (ie, heat the basement) and secure it with more screws.
Any ideas ?