Your piano is made from organic materials, such as wood and leather, and will respond poorly to extremes of humidity.
High humidity drenches the organic wood and leather parts with moisture, aging them and making them break down much more quickly.
In addition, high humidity will affect the tuning, making more frequent, expensive tunings necessary.
Low humidity, particularly that from high heat, especially wood heat, will dry out wood and make it crack.
On a piano, there are two main areas that will be damaged. The sound board, the flat wood surface just below the strings, will warp and separate from the frame, causing strange sounds and buzzing. The entire resonance of the piano can be lost from this.
Also, the pin block, the wooden block that holds the tuning pins, assuring proper tuning, can crack, making it impossible to keep even the finest instrument in tune.
Many of the small parts damaged by extremes of humidity can be easily replaced, but replacing the sound board and pin block is the equivalent of a heart-lung transplant, and should be avoided at all costs.
There are devices to help you:
Get a humidity meter and keep the humidity around 30 to 40%.
There are also add-on devices that use a tank of water to keep a piano in good shape in a dry, low-humidity environment. They are very inexpensive and work well.
If your humidity is too high, the only solution is a dehumidifier.
A piano is designed to last perhaps fifty years, and then must be rebuilt, or junked. Rebuilding a fine grand piano can cost $15,000 to $25,000.
Create a nurturing environment for you piano and you'll be well repaid with an instrument that does not deteriorate as rapidly.
By John Aschenbrenner Copyright 2008 Walden Pond Press All Rights Reserved
See also HOW GOOD ARE TOY PIANOS?
See also ORIGINS OF THE BLACK PIANO KEYS
See also HOW TO BUY AN INEXPENSIVE PIANO OR KEYBOARD
See also WHY GRAND PIANOS ARE BETTER THAN UPRIGHTS
See also PIANO WARS: EVOLUTION OF THE PIANO IN AMERICA