There is a lot of variance of opinions regarding Duo-Art valve
tolerance. I checked out all the references I could find and ended up
using a minimum setting of .032 inch. This setting worked for me and
the zero setting was at 4 inches WG. I kept the pressure low because
the piano was in a small room.
A minimal setting would not make any sense if the setting was done in
a dry climate and subsequently the piano moved to a damp climate. The
valve would then be below my minimum as the wood swells. When I opened
the factory setting I saw ranges from .035 to .049". The accordions
cannot be choked off in the re-opening cycle because the expression
would thrown off.
La Quinta, California - 81 degrees today, breezy, 25% relative humidity