Several weeks ago while tuning a repeat client's Petrof baby grand I noticed numerous cracks in the soundboard. I was almost entirely sure they weren't there at the last tuning - they were just too egregious to miss under any circumstances. After a bit of poking around and head scratching, I began to question my client about the room's temperature and humidity stability - he reported nothing out of the norm. I was doubly confused, because this piano had a humidifier that was supposed to be protecting it against the damage that can come from dramatic wood shrinkage/swelling in response to shifting ambient humidity. The humidifier was definitely working properly, as all the lights on the diagnostic panel indicated proper functioning...or was it? I crawled under the piano to take a look.
Everything looked fine for the most part. The only apparent issue was with the humidistat, the brain of the system that switches back and forth between the humidifying and dehumidifying components as needed to maintain the humidity around the soundboard at about 42%. It was a little too close to the front humidifier rod...the danger here is that the brain thinks the piano is drier than it actually is on average because it's taking readings too close to the dehumidifier rod. In the picture above, the humidistat is the bottom component that appears to be within 3 inches of the rod on the right - it should be at least 12 inches away! If this is the case, the system will engage the drying rods more than it should and over dry the piano.
Nonetheless, the system had been in this configuration for a number of years without harming the piano, so that couldn't be it...then I finally looked at the most difficult component to view without removing - the top of the humidifier tank (a reservoir of water into which hang pads which wick water up and over a rod which gently warms and causes humidity to rise from the moist pads).
And there it was in all its hideous glory - the pads and humidifier heater bar were hopelessly corroded and encrusted in mineral deposits. The former owner, who had the humidifier installed, had not clearly instructed my client to change the pads every 6 months. Although J. was watering the humidifier faithfully whenever the yellow low-water warning light came on, the humidifying component of the system had ceased to properly wick water and the heater bar on the humidifier, which was supposed to gently warm moist pads, was now just acting as a third heating rod in addition to the ones built for this purpose at the fore and aft of the piano. This poor Petrof had been barbecued mercilessly for the last few months as the system struggled to cope with the bone dry New York winter - hence the soundboard cracks. Does that picture above look like a functioning mechanical component, even to the untrained eye? I had J. unplug the system immediately until I could order a new one under warranty to replace it with.
At our next appointment I gleefully ripped (with professional meticulousness...) the defunct system from the piano (I usually get paid to create/build, not destroy!) to pave the way for a proper system that would halt (although sadly not reverse) the damage.
I like to get all my small components ordered in tiny piles before working...this would be a lot easier if Dampp-Chaser would just put different types of screws in separate bags instead of jumbling everything small into one bag...
First step - choose as central a location as possible for the humidifier tank. Install the suspension rods from which the tank hangs.
Then hang the humidifier.
PICK A GOOD LOCATION FOR THE HUMIDISTAT, 12 inches away from the dehumidifier rods and 6 inches from the humidifier. As close to the soundboard as possible - leave the vents on the top right unobstructed by soundboard ribs - all important conditions that were not previously, but were this time, satisfied.
Install the dehumidifier rods at the fore and aft, plug in all the cords and bundle them as tidily as possible so folks walking around the room don't see entrails hanging from the belly of the beast, install the watering tube so it's easy accessed, and install the warning light panel in an easy to see location. All described as if it was far easier than the three grueling hours of crawling around a 3 foot space as a 6 foot man screwing and measuring upside down inevitably ends up being - although I've gotten a lot more effective with practice.
Then carefully instruct your client how to take care of the system, and ask them to do the same with the piano's next owner if there ends up being one! Next time on this piano...diagnosing mysterious problems with a sticking damper and a broken sostenuto - both caused by the same humidifier disaster?