Low Humidity Best?

[Michael Jorgensen]

Hello List,
     I am interested in your opinions concerning humidity.  In Michigan,
most homes simply can't handle 40 percent as windows drip and rot in
winter.  My father, Owen Jorgensen, keeps his Steinways at a constant 25
percent, using only a dehumidifier in the summer.  Every few weeks he
"fine tunes" his dehumidifier by listening to whether the lowest tenor
strings are going flat or sharp with respect to the rest of the piano.
(sharp notes mean dehumidifier must run more).  His 21 year old B has no
cracks or compression ridges, is all teflon which never makes noise and
never needs work, and he hasn't tuned the pianos in years, only touching
up once in a while, yet they're in perfect tune all the time.  Both are
played alot, the pitch stays right up, the strings are not rusty, and
action parts work beautifully.  The A is all original except
hammers/shanks and has many cracks but is 94 years old and likely had
them before any of us were born. I see an awfully lot of "humidity
controlled" pianos kept around 40-50 percent that seem to be falling
apart and rusting away.  Comments?
Mike Jorgensen RPT