I am a Dampp-Chaser Certified Installer as well as being recognized as a Field Expert at installing the Piano Life-Saver Systems.
Installation of a Humidity Control System is by far the best investment you can make to protect your piano! Pianos function at their best when they are kept at a constant level of humidity, around 45% Relative Humidity (RH) is a good level to try to maintain. A Piano Life Saver Humidity Control System installed in your piano keeps your piano at 45% RH plus or minus at most 5%, throughout the year. My experience shows the the RH frequently fluctuates even less than the maximum 5% listed by the manufacturer.
Constant RH allows the thousands of wood and felt and leather parts of your piano to remain more stable. That is, the constant cycles of swelling and contracting due to changing humidity levels is all but eliminated. This means that tuning and regulation remains far more constant.
Proper humidity control helps prevent rust on the strings, sticking keys, and binding action parts that can be caused by fluctuating humidity. It also helps prevent loose keys and action parts, failed glue joints, loose tuning pins, split pin-blocks, and cracks in the soundboard from too little humidity.
Below you can see what a Complete Piano Life Saver System looks like, installed in a grand piano.