<HTML><HTML>Dear Jere, I'll add my 2 cents (or in this case, 30!) with a story that may help you persuade your college folks.  For over a decade, I cared for the pianos at a local college.  20 of their 50 pianos were in one big room.  Invariably, they would all be 15 cents sharp in the summer (when RH was as high as 70%) and 15 cents flat in the winter (when RH was as low as 20%).  Major tuning hassles, needless to say.  I campaigned for years for them to budget for humidity control systems.  I finally got to install them (two 35 watt dehumidifiers per piano, and 1 humidistat per two pianos, if memory serves).  [To cover the other extreme in the winter, we simply used a room humidifier with it's own humidistat.] The seasonal pitch swings were immediately reduced from 15 cents sharp / 15 cents flat to 3 cents sharp / 3 cents flat.  ...A year later someone accidentally unplugged one of the units.  That piano was 15 cents sharp, all the others only 3 cents.  Pretty convincing demonstration of the system's efficacy, methinks. Hope this helps with your dealings with the college! Cheers, Jim Wilson, R.P.T. L.A. Chapter In a message dated 10/10/06 6:37:03 PM, jerefryett@hotmail.com writes: <BLOCKQUOTE CITE STYLE="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px" TYPE="CITE">List, Sometime in the past someone wrote about how humidity changes affect pitch changes. In the article they said that for every % in humidity change the pitch changes by a certain amount also. I have been searching the archives and I can't find those figures. Does anyone know how much the pitch will change with every % of humidity change? I need this to make a point at our local college. Jere </BLOCKQUOTE></HTML>