Hi Don, I'm not using under covers. They will not work with under-the-beam installation (which I understood was supposed to yield more effective humidity dispersion than above-the-beam). I felt fortunate just to be able to order 10 systems at the time, and there've been NO funds available since, because at the time the school of music was operating on a $200K deficit and that's only gotten worse with budget cuts in the last 2 years. Don't think I could have gotten the funds for covers, too. These are Steinway Bs. I installed the first system above the beam and it was extremely difficult, and I could quickly see that servicing the system installed in that manner would be equally as difficult. Also, the hanger bars were buzzing against the soundboard. So I did the rest of the installations below the beam, and also went back and reinstalled the first one that way. Besides, it's not necessarily the low humidity we have as much trouble with as high levels. It rarely gets below 35% here, but it will dip down to as low as 20% once or twice a season, with a few more frequent dips into the lower 30%s. But by April, we'll be in the low 60% range and for about the next 5 or 6 months we'll be in the mid to high 70%s, with occasional measurements at 80%. The biggest hurdle the systems have to overcome is the roller coaster we'll have during the school year, that the HVAC system creates. It'll swing up and down as much as 30 and 40 points, almost week to week, with 20 point changes day to day very common. So, nothing's ever stable. The most stable time of year is the 60 months of very high humidity which has pianos literally busting at the seams. I used the six part systems recommended by Dampp-Chaser (I called them before I ordered), and installed them exactly as I understood the installation instructions. Stability is much better than before, but I also believe a part of that is in not fighting for absolute 440 every tuning, because stability did not improve as much until I started floating. Also, unplugging the humidifier from May until mid October helped tremendously last year, so we did it again this year. So, it is a combination of the two factors you mention. I don't think the system is capable of handling these swings without the covers. I could probably improve the stability more and keep the pianos nearer 440 with more frequent tunings, but the studios are extremely difficult to schedule. The department chair only leaves his studio for meals and a good night's rest. He's back by 7:30 am at the latest on a daily basis. Jeff Don Rose wrote: >Hi Jeff, > >If you are getting a pitch rise with a DC system installed then it is >either underpowered or you are not using back covers/under covers.
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