We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

_______
Free Windows Clipboard Utility
http://www.clipboardmagic.com/

Mike E. Fullerton wrote:
We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

I sure hope the ducts don't get that hot. I don't think that would be
my first choice but don't know what I would use.


_______
Free Windows Clipboard Utility
http://www.clipboardmagic.com/

--
Joseph Meehan

Dia 's Muire duit

"Mike E. Fullerton" wrote in
message ...
We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?


Both of my homes have had this issue. Think of it as a burglar frightening
device. Anyone entering through a cellar window (a favorite for intruders)
will have trouble differentiating between noisy mechanicals and your feet
upstairs as you load the shotgun. Perfect.

On Fri, 02 Feb 2007 10:55:59 GMT, Mike E. Fullerton
wrote:

We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

_______
Free Windows Clipboard Utility
http://www.clipboardmagic.com/

Hi Mike

I think the only fix for it, would be to go to a thicker gauge duct.
Thats obviously a pricy solution. Sometimes you can reduce the noise
by tightening connection not allowing it to slip more as suggested
above.

This is a natural occurance though when a system charges itself and
cools down.

REgards
Dale

If you can pinpoint the exact location(s) of the sound, a little graphite
might work. Plastic wouldn't be a fire hazard, the ducts are only 130
degrees or so.

--
Steve Barker


"Mike E. Fullerton" wrote in
message ...
We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

_______
Free Windows Clipboard Utility
http://www.clipboardmagic.com/

On Fri, 02 Feb 2007 10:55:59 GMT, Mike E. Fullerton
wrote:

We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?


If the ducts are hot enough to be a fire hazard, then
something is seriously wrong with your heating system.

Are these round or rectangular ducts?

On Fri, 02 Feb 2007 12:17:44 -0500, Goedjn wrote:

On Fri, 02 Feb 2007 10:55:59 GMT, Mike E. Fullerton
wrote:

We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

If the ducts are hot enough to be a fire hazard, then
something is seriously wrong with your heating system.

Are these round or rectangular ducts?

Rectangular.

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

On Fri, 02 Feb 2007 12:17:44 -0500, Goedjn wrote:

On Fri, 02 Feb 2007 10:55:59 GMT, Mike E. Fullerton
wrote:

We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

If the ducts are hot enough to be a fire hazard, then
something is seriously wrong with your heating system.

Are these round or rectangular ducts?

Rectangular.

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

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

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

On Fri, 02 Feb 2007 12:17:44 -0500, Goedjn wrote:

On Fri, 02 Feb 2007 10:55:59 GMT, Mike E. Fullerton
wrote:

We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

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?

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?

--
Joseph Meehan

Dia 's Muire duit

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.

Mike E. Fullerton wrote:

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

Buy the cheapest, thinnest car floor mats you can get that don't have any
carpeting on them. Cut them into strips wide enough to do the job. Or,
maybe strips of felt. Or, screw the hanger straps to the duct with
self-drilling screws.

But before you do that, can you SEE it happen? Maybe it's not what you
think.

On Fri, 2 Feb 2007 15:30:22 -0500, "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?

The panels aleady have this X crease in them. I would call the sound
more of a cracking/creaking not a "booming". The sound seems to come
from the metal duct hangers. In fact it seems to come right where the
top of the duct touches the hanger. I put some plastic under the
noisiest one and it didn't seem to help much. The hanger is bent in
slightly at the top as if the installer put them in too tight against
the ducts. I wonder if they were looser if there would not be as much
noise. I can't experiment without taking out the ducts though.

This is drving me nuts and we're losing sleep. I wonder if insulating
the ducts would dampen the noise.

Mike E. Fullerton wrote:
On Fri, 2 Feb 2007 15:30:22 -0500, "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?

The panels aleady have this X crease in them. I would call the sound
more of a cracking/creaking not a "booming". The sound seems to come
from the metal duct hangers. In fact it seems to come right where the
top of the duct touches the hanger. I put some plastic under the
noisiest one and it didn't seem to help much. The hanger is bent in
slightly at the top as if the installer put them in too tight against
the ducts. I wonder if they were looser if there would not be as much
noise. I can't experiment without taking out the ducts though.

This is drving me nuts and we're losing sleep. I wonder if insulating
the ducts would dampen the noise.

Actually removing the hanger, adding some duct insulation and replacing
the hanger should help, assuming the problem is what you think it is. Hard
to tell from here.

--
Joseph Meehan

Dia 's Muire duit

. I would call the sound
more of a cracking/creaking not a "booming". The sound seems to come
from the metal duct hangers. In fact it seems to come right where the
top of the duct touches the hanger. I put some plastic under the
noisiest one and it didn't seem to help much. The hanger is bent in
slightly at the top as if the installer put them in too tight against
the ducts. I wonder if they were looser if there would not be as much
noise. I can't experiment without taking out the ducts though.

This is drving me nuts and we're losing sleep. I wonder if insulating
the ducts would dampen the noise.-

This sounds like the same problem we had and I FIXED IT just last
week. REPLACE the metal hangers. (We did all of them.) Buy some
rubber tie-down straps from a hardware store. Cut them into strips
about the length of the metal hangers. Take down one hanger at a time
and replace it with the rubber strips. We screwed them into the duct
and nailed them into the joist exactly where each metal hanger used to
be. Haven't heard a thing since. The rubber allows slight movement of
the ductwork so it is not forcibly rubbing against any solid object.
We have also replaced sections of round ductwork with flexible duct in
places where it was jammed in too tight between joists or framing.
That helped a lot, too. The idea is you have to allow the ductwork to
move slightly as it heats and cools. Trying to force it to not move
(as one suggestion above) is nuts. It just makes it worse. If your
noise is like ours-clicking and cracking from ducts expanding and
contracting-allowing them this extra movement will solve the problem.

On Fri, 02 Feb 2007 10:55:59 GMT, Mike E. Fullerton
wrote:

We recently bought a 25 year old house. It uses gas heat. When it got
cold and the heat came on I noticed a very loud cracking sound when
the heat came on and again when it turned off. This is from the
expansion and contracting of the galvanized heating ducts in the
basement. The ducts are on metal hangers so they are not touching the
floor joists.

I have never encountered this problem in any other house I have lived
in. How to best fix this? Someone suggested putting a strip of plastic
vapor barrier between the hanger and the duct to allow slippage.
Couldn't that be a fire hazard?

_______
Free Windows Clipboard Utility
http://www.clipboardmagic.com/


I had some ducts that did that. I took a piece of PVC pipe, 3/4 inch
I think, and put it inside the duct so it was jammed between two
anchor points (bends, ends, elbows) into a bow that pushed on the
metal duct in the middle of the run. That stopped almost all the
noise.