I put our 2 other mechanical hygrometers with pointers in my workroom this night and found that all 3 show the same value. So I assume that the readings are correct, i.e. that the Beurer hygrometer is working.
Ruedi
okay, though it is not mentioned in the manual, or instruction sheet there is a plastic sheet covering the display with the temp at 22 degrees and humidity at 46% -- once I removed this --difficult to even find sheet- my problem was solved
I'm sorry, I don't understand the question. My Breurer HM 16 doesn't have a plus or minus button. I put the battery in and that was it and I read the temperature (C or F) and the humidity and I am super happy with the device.