Hygrometer Calibrating and Suggestions on Digital

[toasty]

Anyone have any suggestions on a good brand that monitors temperature and RH? I tried calibrating my analog, but I'm a little unsure if I did it right. I did exactly as was directed....Filled a cap with salt, got it damp with distilled water, let it sit for 24 hours. Now it's at the 58% mark. Is it really possible for it to be off by 17 points??

[basil]

If what you write is all you did, all you've done so far is find out where exactly you hygro reads in an environment where 75% rh is known. Yes, it is possible for your hygro to be that much off. Now, set it so it reads 75. If you have a cheap analog, there'll be no way to set it.

You can find an accurate, digital hygrometer here

[Bkcloud114]

Try it again....... this time use two ziplock bags and see what type of reading you get.

[toasty]

sorry, i left that part out. I did use 2 ziplock bags and pushed out the air from both of them. I'm sure the hygro was just way off now after reading online all day. I ordered that Humigauge Perfecto, so hopefully that was a good one.

[mauied1101]

You know what - my digital was coming up with some odd (but consistent) numbers so I put it to the salt test - it's sitting at 59% RH. Temperature is accurate... How the heck could a digital be off by that much?

A little background - the digital hygrometer is about 8 years old - hadn't used it in 5 years(?) - no battery, so I took it to Target and the watch person just found one that fit. Screen lit up so I assumed it was ok. Temperature is accurate - but again, my questions:

1. Can a digital really be off by 16%?
2. Is it that my hygro is just old?
3. Does the size (and thus the power) of the battery affect the reading (and then only the RH and not the temp)?

Gonna go look for a hygro...

Happy Easter all.

[Desert Rat]

Is it really possible for it to be off by 17 points??

1. Can a digital really be off by 16%?

Yes, it is entirely possible for a digital or analog hygrometer to be off by 16 or 17 points (or more). The technical term for such a hygrometer is "junk"- my garbage man has been the recipient of several fine examples of "junk" hygros.

My little $20 hygros came from Radio Shack, but I think they quit offering them, so you might try Basil's site.

Good luck