Hello list, I have received a few inquiries regarding the accuracy of Dampp-Chaser hygrometers. Customers have purchased the units in quantity, set them all up to run side by side, and then have become concerned about the results. We contacted the manufacturer in Sweden and they verified the following information. Measuring range: 20-95%RH Accuracy within 50-70%RH: +/- 3%RH Accuracy outside 50-70%RH: +/- 5%RH I find that these specs are typical for hygrometers priced similarly to ours. Unfortunately, 42% RH could be read anywhere from 37%RH to 47%RH when read with these instruments. We believe, however, that the instruments do measure changes in relative humidity quite accurately. We had hoped technicians would use them to show piano owners the variations in the piano's environment (maximum versus minimum readings) rather than use them as scientific instruments. I use either data loggers or high end ($1500 plus) hygrometers in my research. The old saying, you get what you pay for, is really true for hygrometers. Another thing I occasionally do is find myself questioning the reading only to realize a little later that it was set on either the max. or min. I feel pretty dumb when I figure this out, but thought I would pass it along just in case. Thanks, Roger
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