Pianos are affected by changes in humidity. A majority of the piano is made out of wood, which absorbs moisture when it’s damp and becomes dry when the humidity dips below 42% . The ideal humidity for pianos is 42%-45%. The closer to that percentage you can keep the room that the piano is kept in, the better the piano will sound, and will hold the concert pitch. The concert pitch is A-440 C.P.S. This is the standard pitch that all orchestras tune to. The piano was designed to be at this pitch and it’s extremely important that it be tuned regularly to keep it there. Realizing it’s next to impossible to keep a room at or near 42%, there is a solution.
I highly recommend installing a climate control unit directly into the piano. There are two different types of units. One adds moisture to the piano when it’s dry, and one dispels moisture when it’s humid. The climate in Florida is humid most of the year, which means most pianos only require a damp chaser, which is basically an adjustable 15 watt heating rod in combination with a humidistat. A humidistat is a switch that measures humidity and controls the heating rod. Some technicians install a rod without a switch. I don’t recommend doing that because if it does get to dry in the room the piano will be absorbing to much heat which can dry out the wood and crack the soundboard and pin block.
I have installed many complete climate control units in pianos and witnessed much success, especially in schools and churches which typically experience extreme changes in temperature and humidity. The pianos with climate control units stay in tune and hold the concert pitch much better than those without.