Insulation of Heating & Cooling Ducts

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
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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.
:-)
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Naaah Rich daddy.

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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



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Hawgeye, Thank you for your recommendations.
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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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