<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html>   Don wrote: <blockquote TYPE=CITE>Hi Ric, I don't have any real data, but I suspect + or - 2% would be the range one would have to shoot for--and one would want a rapid cycling between -2 and +2. I believe someone on the list said the DC controller cyles every hour in the bottom cover unit. The slower the cycling the narrow the range would have to be.   <a href="https://www.moypiano.com/resources/#archives"></a> </blockquote> Hmm I wonder.... would be interesting to get some real data to be sure. For my own part, we only have a serious problem with stablility in the winter, and only then when the temperature approachs or gets below frezzing. Otherwise humidity inside our building is never below 35 % and never above 60%. For well three quarters of the year I dont have any real problems with pitch stability in the larger rooms. And the only reason I do in the smaller rooms is because students keep comming in and turning up the panel oven to 30¤ C. (at least I think thats the only reason) All that being said... tunings hold better with the DC installed then without. At least they do on the pianos here at the University, and the others I have installed around western Norway. No doubt about it. Still, given the constant need to insure someone is takeing care to see these are always plugged in, filled with water, not moved around without being sure the system is safe... etc etc... I would like to see what level of room climate stability is "good enough" RicB   -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A>  </html>