dicko wrote:

On Fri, 23 Nov 2007 13:19:27 -0800, "Zyp" wrote:



Use UL-181 approved tape only. The rubber backed duct tape of yesteryear is
no longer approved for flexible ducting. The UL-181 is a newer standard
that uses acceptable adhesives and is used by the manufacturer of flexible
ducting to connect collars. It is also advisable to use a "mechanical
restraint" on duct connections. A 48" zip tie is used today by the trades
to provide the mechanical restratint requirment. When ever you join two
pieces of flexible ducting, you must use a metal collar or sleeve to connect
them. Duct sealing mastic is also approved for flexibe ducting but it too
must have the UL-181 approval. Duct sealing mastic is designed to stay
flexible and expand as the ducts are warmed. Approved tapes also have a
none permeable [breathing] backing so the adhesives have a longer life than
those in rubber backed duct tape [cloth tapes.]

Through recent testing it is know that most residential air duct systems
have a leakage rate as high as 30%. By providing superior sealing you can
cut that to 6%.

I hope this is helpful.


Thanks, It helped a lot. The roll of metallic tape that I have does
not mention UL-181 anywhere on the package. I'm going back to the
store to search for a roll that is UL listed.

-dickm

It won't be cheap, but you'll be glad you did.

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