Building and Construction - Insulation of Heating & Cooling Ducts

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Insulation of Heating & Cooling Ducts

John1963

2007-12-20, 9:25 am

I have a 1 story, 30 yrs old Rancher with a 2000 sg. ft. walk out basement.
The Main metal heating/cooling duct running the length of the basement and
has metal 8" branching ducts to the first floor rooms. The 8" ducts are
supports on metal straps between the 12" joist. There wasn't any insulation
originally on any of these metal duct work main or the branches. The
basement is sectioned or divided into several rooms but should still be
considered only partially finished as only one of the basement rooms has a
suspended ceiling and carpeting.

To improve the heating and cooling to the first floor living area, I
insulated a few of the branch runs to 2 of the first floor rooms. As near
as I could tell by checking the temperature at the outlet registers in these
2 rooms, the insulation seemed to help. This was a lot of neck and back
bending work, stuffing the fiberglass batts around the metal ducts and then
covering all with Styrofoam boards followed by 1/4" ply wood. There is
also the problem of working around the plumbing and wires attached to the
joist. I covered the fiberglass with the rigid Styrofoam and plywood for
both appearance and I think it is also needed for building code compliance
based on the caution wording on the fiberglass batts.

For the basement room with the suspended ceiling, another approach was
taken. Instead of insulating the duct in the ceiling, these were replaced
with expandable (accordion like) insulated plastic ducts. This seems to be
the better approach for several reasons. First it was easy, just removed
the metal ducts, cut the expandable duct to length, connect and the job is
done. But, I seemed to get an unexpected (to me) benefit. The sound level
from the air circulation fan to the room supplied by the plastic duct was
significantly reduced to where it is hardly noticeable.

The rooms where I just insulated the metal ducts with fiberglass are still
annoying noisy when the circulation fan is running. We often increase the
volume on the TV when the fan begins to run both during the heating and
cooling season.

Questions:
1) Should I continue using the replacement approach and just discard the
metal ducts to a metal recycler?

2) Should the main trunk be insulated?

3) I was considering wrapping it with the Reflectix type insulation. Cost
effective?

Thanks for comments.
John

Matt Whiting

2007-12-20, 1:25 pm

John1963 wrote:
> I have a 1 story, 30 yrs old Rancher

Are you sure the 30 year-old is really a rancher or is he just a plain
old cowboy? 30 is pretty young to be a rancher.

:-)

Glenn

2007-12-20, 5:25 pm

Naaah Rich daddy.

"Matt Whiting" <whiting@epix.net> wrote in message
news:J3zaj.1176$2n4.28608@news1.epix.net...
> John1963 wrote:
>
> Are you sure the 30 year-old is really a rancher or
> is he just a plain old cowboy? 30 is pretty young to
> be a rancher.
>
> :-)

hawgeye

2007-12-21, 9:25 am

"John1963" <johnareichert@bellsouth.net> wrote ...
>
> Questions:
> 1) Should I continue using the replacement approach and just discard the
> metal ducts to a metal recycler?

Probably, but I would do (or have it done by a pro) the calcs on the duct
sizng before I replaced everything with the same size that was there,
especially if some rooms are warmer or colder than others.

> 2) Should the main trunk be insulated?

Yes

> 3) I was considering wrapping it with the Reflectix type insulation. Cost
> effective?

Looks like it is already starting to pay for itself.

> Thanks for comments.
> John

--
hawgeye ©

John1963

2007-12-21, 5:25 pm

Hawgeye, Thank you for your recommendations.

"hawgeye" <hawgeye96@ATTITUDEcomcast.net> wrote in message
news:OPWdnfuu48xYL_banZ2dnUVZ_sCtnZ2d@comcast.com...
>
> "John1963" <johnareichert@bellsouth.net> wrote ...
>
> Probably, but I would do (or have it done by a pro) the calcs on the duct
> sizng before I replaced everything with the same size that was there,
> especially if some rooms are warmer or colder than others.
>
>
> Yes
>
>
>
> Looks like it is already starting to pay for itself.
>
>
>
> --
> hawgeye ©
>

ransley

2007-12-21, 5:25 pm

On Dec 21, 2:13=A0pm, "John1963" <johnareich...@bellsouth.net> wrote:
> Hawgeye, Thank you for your recommendations.
>
> "hawgeye" <hawgey...@ATTITUDEcomcast.net> wrote in message
>
> news:OPWdnfuu48xYL_banZ2dnUVZ_sCtnZ2d@comcast.com...
>
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For noise I believe a flexible collar can be used, you remove a
section of duct so vibration is reduced. I had round duct and removed
it all and slid on the sleeve insulation. Your basement will be colder
but if you dont care insulate all of it.

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