How reliable are hygrometers?

I need a hygrometer to tell me what the percentage of relative humidity is, but I don't need one to tell me that the air is getting dry in my house and I need to fill up the Oasis and make sure it is tucked in my ukulele.

Two ways of looking at the issue. If it is dry where you live keep them cased and humidified. Knowing the humidity percentage is not necessary. If during the dry season things get back up above 35%, it happens, I can leave an instrument or two out on their stands to play when the mood strikes. This is were hygrometers come in handy.

For those that don't want to case their ukes, or who don't have hardcases or who don't want to buy an Oasis humidifier for every case, it is very helpful to have a hygrometer. I keep three ukes hanging and often one in a stand.

I spent some time trying to verify and calibrate hygrometers several years ago, and wrote about it in two articles on my blog:

https://doctroid.wordpress.com/2010/02/20/i-just-want-to-know-the-humidity/
https://doctroid.wordpress.com/2010/02/27/i-know-the-humidity/

I was looking at two Caliber IIIs, an electronic hygrometer from Radio Shack (or actually two, because it had a main and a remote unit), and a fistful of analog hygrometers. Conclusions I came to:

1. The Calibers are fine.
2. So is the Radio Shack.
3. The analog hygrometers are junk. (Including the one being sold to clarinetists to keep their instruments from cracking, and the one being sold to pet owners to keep their reptiles and amphibians alive.)
4. Somehow my wet bulb psychrometer was either built or used wrong, in both its incarnations, despite its seeming idiot-proof nature. I don’t know what was wrong, I being the idiot in question.

Doctroid said:

I spent some time trying to verify and calibrate hygrometers several years ago, and wrote about it in two articles on my blog:

https://doctroid.wordpress.com/2010/02/20/i-just-want-to-know-the-humidity/
https://doctroid.wordpress.com/2010/02/27/i-know-the-humidity/

I was looking at two Caliber IIIs, an electronic hygrometer from Radio Shack (or actually two, because it had a main and a remote unit), and a fistful of analog hygrometers. Conclusions I came to:

1. The Calibers are fine.
2. So is the Radio Shack.
3. The analog hygrometers are junk. (Including the one being sold to clarinetists to keep their instruments from cracking, and the one being sold to pet owners to keep their reptiles and amphibians alive.)
4. Somehow my wet bulb psychrometer was either built or used wrong, in both its incarnations, despite its seeming idiot-proof nature. I don’t know what was wrong, I being the idiot in question.

Click to expand...

Rich, thanks for sharing your info. Those blog posts were both informative and entertaining, and I enjoyed your self-deprecating humor in your writing style.

So, it seems that we can conclude that hygrometers vary widely.

I have a Caliber IV, that I purchased supposedly calibrated by and directly from violin luthier David Burgess for $30, that's reading 65.3 F and 45% RH and 3" to the right of it is an ACURITE ($9 on Amazon) that's reading 68 F and 35% RH.

(These levels go up or down in relation to the OUTSIDE humidity when it's raining or snowing, yes we have draft leaks in our house and with furnace running 24/7 entropy and positive air pressure inside is likely to disperse air/heat/humidity outside through whatever leaks.)

If I spread them 10 ft apart, they read the SAME from opposite ends of the room, but if I place them close together they are anywhere from 10% to 25% apart in their RH% readings.

I am running an ultrasonic cool mist humidifier that goes through 3 gal of water in 24 hrs before needing a refill, as well as an ultrasonic/evaporative humidifier 24/7 with takes about 3 days to finish off about 4 gals of water