I agree with you on the poor accuracy of cheap digital hygrometers. I've been resisting spending $$ on a real one until I put my first board in a piano. I have four of the little cheap ones from three different manufacturers. They are all pretty close together except one of them. But you are right, I will not know for sure unless I get a real one. Two are from Damp-Chaser. I realize they are a decent sales tool, but why promote them as a means to determine RH in an environment? Terry Farrell Piano Tuning & Service Tampa, Florida mfarrel2@tampabay.rr.com ----- Original Message ----- From: "Delwin D Fandrich" <pianobuilders@olynet.com> To: <pianotech@ptg.org> Sent: Monday, January 15, 2001 3:35 PM Subject: Re: Climate Control Promotion > > ----- Original Message ----- > From: "Farrell" <mfarrel2@tampabay.rr.com> > To: <pianotech@ptg.org> > Sent: January 15, 2001 10:28 AM > Subject: Re: Climate Control Promotion > > > > Hi John. I like the DC systems quite a bit, but I am disappointed on the > > accuracy of their humidistats. Have you ever put the min/max hygrometer > next > > to the humidistat and checked it for a lengthy period of time (also good > to > > monitor room RH at the same time)? Also a good excercise is to plug an old > > electric clock (no digital) into the humidistat to see how long it runs > over > > a period of time. > > > > My own observations with many humidistats is that rather than turning on > and > > off within a few % of 42% RH, the regular calibration humidistats turn on > > and off in the 57% to 65% range. I wish I could keep my pianos in the 42% > > range. > > > > Terry Farrell > --------------------------------------------------- > > Terry, > > Have you checked the accuracy of your hygrometer? The most common type -- > i.e., those available through Pianotek, etc. -- are generally not all that > accurate. Relative humidity is a very difficult thing to measure with any > accuracy. It will cost you several hundreds of $$$ to get one that will have > certified accuracy much better than +/- 5% or so. I've checked a couple of > the inexpensive digital hygrometers against my sling hygrometer and have > found them to off as much as 20%. > > Still, while I trust the sling hygrometer, it is real difficult to get an > accurate reading from it right up next to the soundboard. So, I would > suggest checking the digital against a sling from time to time and making up > a correction chart. While the inexpensive digitals may not be all that > accurate, they do seem to be reasonably repeatable. > > Del > >
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