Just last week I tuned a Yamaha P22 with a 50 watt dehumidifier rod, which was hot when I started tuning. Initial measurements of all A's showed the piano within two cents of target. I said to myself, "Boy, am I glad I installed that dehumidifier!" After fine tuning all 88 notes, I went back and checked the A's again, and found octave 1 through 5 to be 5 cents sharp! As Charlie Brown would say, "Aaaarrghhh!". The rod was cold at this point. It must have switched off somewhere around halfway through tuning. Room temperature was 70 degrees. I don't know what to do about this. No matter where I tune that piano, it will be 5 cents wrong when the rod toggles. Should I tune cold in the fall, assuming it will be off most of the winter and tune hot in the spring assuming it will be on most of the summer? Should I just unplug every humidity system before tuning? Should I move the rod up, down, or sideways? Should I put in a lower wattage rod? It sure would be nice if the humidistat cycled the rod more like an electric stove: on and off several times a minute, varying the percentage on vs. off relative to the humidity. The temperature of the rod and the air in the piano would gradually rise as humidity rises, over a period of days, rather than running full blast for hours, then off for hours. That doesn't solve the problem of temperature drops from opening the cabinet to tune, but it would avoid the major change when a rod turns off during tuning. I really hate tuning an in-tune piano twice. Greg Graham
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