Keybed Warping

[Cliff Lesher]

I am wondering if anyone has seen this before:

The piano:  Chickering console, Serno 185664, Mfd ~1943.  Located near
corner of inside and outside walls.  Outside door nearby.  House has no
a/c.

Last winter, I was asked to look at this piano because, "the keys
weren't working right."  During discussion, I learned that the piano had
been worked on when the owner lived in NC.  The owner thought the
problem might have been caused during the move from NC to PA.

My inspection revealed the key height to be extremely high.  The keys
bottoms were above the keyslip, they were no longer "engaged" by the
front-rail pins, and the dip was nearly 3/4".  It was no surprise that
there was severe hammer blocking.  These conditions were worst at the
center of the keyboard and tapered toward each end.  The keyboard crown
was readily apparent, looking like an exaggerated example to demonstrate
the concept.

I concentrated on the balance rail and noticed that the punchings were
"normal" but the rail was shimmed up about 1/8".  Taking the wholesale
approach, I removed the shims to see the effect.  After doing so,
everything dropped right into place.  All parameters were generally
correct.  I closed the piano and left, but not without a feeling that
there might be more to this.  I communicated this to the grateful owner.

Sure enough, the follow-up call came in mid-July, on perhaps the most
humid day of the year.  This time the symptoms were just the opposite:  
zero dip, etc.  My conclusion was that the humidity cycle affected the
keybed causing it to crown toward the floor in summer and return to
near-flat in winter.  The shims went back in for the time being. 
Humidity discussion followed.

Questions:

As stated earlier, has anyone seen this?

Along with changing the location of the piano, will a climate control
handle this magnitude of change "outside the cavity?" 

Any other ideas?

Cliff Lesher
Lewisburg, PA