Humidity

[WilsonianJ at aol.com]

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 at hotmail.com writes:


> 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
> 
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