Mark- The fact that it was April and was changing should not make any difference. It should have remained stable. The fact that the customer is still using water says the humidifier pads are ok. This is normally the primary cause for stability going away. How is the humidistat installed? What is its location? Is it upside down with the edge close to the soundboard and is it 6 to 12 inches from the humidifier? Is the humidifier installed between the beams? Can you expect a reasonable air flow around the humidifier tank? What power level dehumidifier rods are currently installed? Your thinking of installing another rod suggests that the piano is going sharp. You may need another dehumidifier but that's not where I would start. From what I can tell of your message, it sounds like you have made a good installation. Answers to the above questions will provide more information and we can then tell more. I would not disconnect the humidifier during the summer. Very little water comes off it without heat from the heater bar and pads deteriorate much more quickly if they become dry. As a last comment, let me refer you to a detailed aswer/comment by Randy Potter several months ago. He said that before he does anything to a piano he tightens or at least checks the tightness of the plate bolts. This may or may not help but I offer it none the less. Bob Mair, Dampp-Chaser
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