"nestork" wrote in message
...

Peter:

You could try an infrared inspection.

If warm air is being blown into the ceiling joist space at a separation
in the duct, an infrared inspection will show the area of the ceiling
that's the warmest, and that would logically be closest to the
separation in the duct.

Also, air flow through ducting is highly dependant on how much air flow
resistance the duct offers. The warmest ducts will be those with the
greatest amount of warm air flowing through them. An infrared
inspection camera will show whether there's any air flow at the UPSTREAM
end of the duct. It could be that the length of the duct combinded with
it's size and offsets provides too much resistance to air flow, so
there's little air even entering the duct. You might need to add a
booster fan to that duct.

Short of infrared, you could try to FEEL the wall, by hand, for warm spots
in the walls/ceiling. This might give an indication of where the problem
begins, if separation/leakage is the problem.
Toward that end, some people's hands are more sensitive than others,
depending on how dry, calloused, weather-worn a pair of hands are. Kids/the
wife might have better hands for this.
--
EA





--
nestork