Dale: I have used a sheet of mylar(provided by Dampchaser) under a Yamaha grand that sat near a huge cold air return. I covered the entire open area below and cut out the area where the water container sits. This worked tremendously well! >From year to year this piano doesn't deviate more than 2 cents. Before the mylar, I was having all kinds of problems maintaining pitch integrity.This last year the piano needed just a very minor touchup.(House has Aprilaire and piano gets used sporadically) It also helps if you would ask your customers to keep the lid down on the piano-except when they are entertaining and wish it to be open for "show". It also keeps the interior much cleaner-but of course, you already knew that. Hope this helps. Oh, incidentally, it does make it a bit more difficult to change the pads, but fasten the mylar in such a way that you can easily drop the sheet in the area of the water tank. Use large-headed thumbtacks to accomplish(like the ones DC provides to connect dehumidifier rods in an upright piano. Bob Bergantino, RPT South Euclid, Ohio
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