Heat duct against basement wall

[nelson]

I am finishing my basement and woudl like to put heat/ac ducts at 12" above floor level (mostly to get heat coming out at a low level). This means placing some of the heat ducts against the concrete basement wall. Most basements I have seen put the ducts in the ceiling. Is it OK to place the ducts against an outside wall (I would be placing insulation behind the duct) or would condensation be an issue :?:

[Rich]

As long as you provide a thermal break or vapor barrier between the duct and concrete you should be ok.

[nelson]

I hear differing theories on vapor barriers - the following article suggests
that having a vapor barrier only traps the moisture in the place where you want it the least ie in the wall

http://www.buildingscience.com/resources/foundations/basement_insulation_systems.pdf

[Rich]

I tend to relate all questions to whatever my current project is :) So I tend to answer accordingly - meaning conditions are different in most cases. We have all the exterior insulation and waterproofing (not dampproofing) in place, as well as humidity control, etc.
I was only suggesting a vapor barrier in the one location - between the wall and the duct. Not the whole basement. By doing that - water can still dissipate to the sides of the vapor barrier but not directly condense on the duct. That is if you follow the other recommendations in the article to allow vapor/water to dissipate to the interior.. i.e. permeable materials such as drywall.

[mjpliv]

The rule of thumb is always place the vapour barrier on the warm side of the insulation.