Humidistat Accuracy

Ron Nossaman RNossaman@cox.net
Mon, 02 Dec 2002 16:15:04 -0600


>I have a big pile of copies of a full-color beautiful Damp-Chaser 
>marketing handout that describes how the use of their dehumidifier system 
>keeps the relative humidity (RH) of the atmosphere in the area of the 
>piano soundboard at maximum of 42% RH. Why is it that when I place the 
>probe of my NIST-certified 1% accuracy hygrometer on top of my Damp-Chaser 
>humidistat, it reads 55% RH? When I place the probe on top of the 
>soundboard it reads 55%. When I place the probe in the middle of the room 
>where the piano resides, it reads 55%. The heater rods are not warm. The 
>atmosphere next to the soundboard should be 42%. The room and  everywhere 
>else around the piano is 55% RH. The humidistat should turn on 
>at.......something near 42% RH.  I'm looking at the pretty 
>graph:  http://www.dampp-chaser.com/main.html  It suggests that RH won't 
>even come close to 55%. Where is the discrepancy?
>
>Terry Farrell


Pardon me folks, but while you are busy answering a question on using a 
Dampp-Chaser humidistat on a room de-humidifier, wasn't Terry's question 
here about a Dampp-Chaser system correctly installed in his piano? That's 
how it reads to me, and I'd be curious as to why the heater rods aren't on 
at 55% RH too.

Ron N


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