You didn't mention what you did to correct the problem.  Perhaps you
adjusted the poppet upwards to compensate for the shrunken pouches.
That would seem to take care of the matter if the pouches are as shrunk
as they are going to get.  However, if the pouches were taut and had no
upward or downward play that is another matter.  New pouches would
suffer the same fate.

I once had an upright Farrand with the vertical pouches that shrank
because the piano was above an old cast iron heat retaining furnace
housed in the basement.  It kept the humidity to the point that the
piano slowly refused to play.  Valves were being pushed towards the
open position by the shrinking of the pouches.  As a teenager with
no knowledge of rebuilding, I simply stretched the pouches by gently
pressing on them with my thumb.  The piano worked perfectly for several
year, and was sold.

The floor heating may well have altered other parts of the mechanism.
My experience in the desert is that the Duo-Art requires tweaking of
the springs on both Theme and Accompaniment, depending upon the season.
A large humidifier, set for 45% relative humidity, has gone a long way
in reducing the problems associated with dry air.  I am certain that
adding a rug would not change anything.  I have no experience with
a tube humidifier, but my concern would be that those parts closest to
the unit might be too damp and cause warping.  My Ampico is far more
sensitive to the dry air as many parts, particularly the stack, can
leak.

Oregon Scientific makes several hygrometers that seem to be a little
better quality than some:
http://www.weatherconnection.com/oregonscientific.asp?s=g&kw=scientific+oregon

Costco recently has them for $19.  While the Oregon Scientific instruments
agree with each other, none of my other hygrometers -- electronic or
analog -- read the same.  I have yet to find an old fashioned wet-bulb
hygrometer.  The new wet-bulb gadgets are made of plastic.  The scales
are so compressed that it is nearly impossible to get an accurate
reading.

Bill Chapman, near Palm Springs, Calif.