[CAUT] FW: Temperature/Humidity range

[Fred Sturm]

On 1/13/06 12:32 PM, "Mark Dierauf" <pianotech@nhpianos.com> wrote:

> 
> After years of complaining about the environment in the Music Building
> at a school that I service, there finally seems to be some movement
> towards at least exploring a solution to the problem. I have been asked
> to provide a range of both humidity and temperature that would be
> considered the minimum requirements for the pianos. Right now, humidity
> swings between 20% and 70%, measured with my radio shack digital
> thermo/hygrometer, although I have a hard time believing that it doesn't
> drop lower than that. Temperatures in the heating season frequently
> reach into the upper 70's, with a few rooms hitting well above 80F on
> occasion! I have suggested that anything outside the 30% - 60% range is
> bad for the pianos, with an ideal of mid 40%'s, but I don't know how to
> answer the temperature question. Any suggestions?
> 
> Mark Dierauf, 
> Concord, NH
> 
> 
> _______________________________________________
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> 
I'd say that temp will be fine if it's comfortable for the people in the
building. IOW, a reasonable small range, which will typically be between 68
and 75 F. They'll have to maintain that to keep the people happy. (Yes, Ron
is correct that you might have your pianos happiest at a constant 50
degrees, but that ain't gonna happen).
    Where you'll find trouble is during the hours when people are absent. It
might be that they want to cut temps overnight every night and bring them up
in the morning. And/or shut off or drastically cut heat or AC during breaks.
For those instances, I'd try to lobby for caps on the extremes - maybe 80
and 60 for longer breaks, 75 and 65 for overnight.
    The real problem, from the point of view of the piano, is the effect on
RH of those temp fluctuations. If they install equipment to control
humidity, it will probably control dew point (IOW, absolute quantity of
water vapor per volume), not RH. And that's fine, as long as temperatures
don't vary too much.
    Don Rose is correct that a Radio Shack hygrometer isn't accurate at the
extremes. I'd bet your reading of 20% is really 10% based on my own
experience with these devises.
    The biggest financial stumbling block will likely be the lack of
adequate vapor barriers in the exterior walls. At the temperatures of NH,
you aren't going to be able to add much humidity to the air without causing
major structural issues unless vapor barriers are there. Retrofitting those
is very costly.
Regards,
Fred Sturm
University of New Mexico