Joseph Meehan wrote:
Mike E. Fullerton wrote:

On Fri, 02 Feb 2007 14:39:49 -0500, Goedjn wrote:


On Fri, 02 Feb 2007 19:23:20 GMT, Mike E. Fullerton
wrote:

..

Are these round or rectangular ducts?

Rectangular.

sometimes creasing the panels in those in
a big X will reduce the booming.

How do you crease the panels?


That is a professional job. Could that "crackling" sound be described
as a booming? If so can you pinpoint the source?


I think what you're describing is also known as "oilcanning", when a
rectangular panel in the ductwork pops in or out like the bottom of an
oiler.

We've got one of those in our office HVAC ductwork which does that when
we shut the blower down for the night.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.