At the risk of being "attacked" by Rick Parks on this (if you're reading this Rick I'll be looking for your suggestions) I would concur with the Dampp-chaser installation as PART of the solution. However I would go with a 38w unit (or perhaps even 50w if you can get it) and ABSOLUTELY have the humidistat installed with it......
I'm here, Peter
--- Watching your every move! (I'm worse than gum on the shoe I think)
Anyway, I agree with Peter here (to a point). If you cannot control the room get a Damp-chaser system. Now, does someone wish to help Peter up off the floor?
Actually, I would think through more, as to controlling the environment of the room the piano is in --- as this IS THE BEST for the instrument. But, I do think that I have always remained consistent on the point that you must control the environment for the instrument in any way possible. It is simply that I attempt to offer every suggestion first that controls the room. In last resort I fall back on Damp-chasers.
Simply put though, IF you go with the system--- FOLLOW THE DIRECTIONS!!! It is worse to spend all that money, and then let it develop crust-slime-mildew through neglecting to upkeep it. That leads to REAL problems.
Edit: I must be losing it, Pete--- 7 hours behind your comment!