Whatever you do, don't use the insulation that goes inside the metal duct.
Can't believe that crap is even on the market. And don't use the cardboard
duct stuff either if that is still on the market. As far the the flex duct,
if you can shorten runs and use wider ducts it will help reduce friction in
the duct, but metal is always going to be better if done properly. But both
need to be planned by someone who knows what they are doing. Many HVAC guys
don't even know what they are doing, unfortunately.


"Jeffrey J. Kosowsky" wrote in message
...
The previous homeowner did a DIY job of installing a new furnace using
a twisted maze of flex duct to make all the supply and return runs in
the basement.

Several heating contractors have advised us that flex is not intended
for long runs and that this is the most flex they have ever
seen. Also, there are no dampers and in some areas the flex is pinched
and the insulation tearing.

Couple of questions:
- Is replacing flex with rigid sheet metal duct work generally
worthwile?

- Is it better to use custom sheet metal fabricated to fit tightly
between the joists or should we go with standard "round" ducts?
More generally are there different qualities of sheet metal that
we should be concerned about?

- One contractor talked about "vinyl clad duct insulation". Is that
a good insulation solution?

- What types of dampers should we be installing for best results?

- Any other questions we should be asking regarding duct work?