Dehumidifier & Hygrometer disagree about humidity level. Who do you trust?

J

jerichojews

Well-Known Member
My dehumidifier has a digital display, and I have a cheap Acurite hygrometer/thermometer. However, sometimes the humidity that is shown on these 2 devices can differ by as much as 15%. Dehumidifier says that its 70% rh, while hygrometer says 55% rh.
Who do I go with? Do I call in a third opinion?
 
no clue

no clue

Well-Known Member
Some hygrometers can be calibrated. If yours can it will have a button on it that says calibrate. The one I have is a xikar and you can calibrate it..costs about 15 bucks and works great.
 
T

T.H.Cammo

Well-Known Member
I'd say just split the difference! The exact relative humidity (RH) isn't really that critical, as long as you're somewhere in the ballpark. If you really must find out which one is more accurate; here's how to do it.

Turn on "The Weather Channel" on cable TV, or find some website that gives realtime, complete, weather reports for your local area. Using either of these methods, you should be able to determine the exact RH in your area at any given time. Now take your dehumidifier and hygrometer out of your grow area and set them up in a neutral area (outdoors, in the shade). Now all you have to do is compare the actual RH with whatever your devices say, to find out which one is more accurate.
 
J

jerichojews

Well-Known Member
T.H.Cammo said:
I'd say just split the difference! The exact relative humidity (RH) isn't really that critical, as long as you're somewhere in the ballpark. If you really must find out which one is more accurate; here's how to do it.

Turn on "The Weather Channel" on cable TV, or find some website that gives realtime, complete, weather reports for your local area. Using either of these methods, you should be able to determine the exact RH in your area at any given time. Now take your dehumidifier and hygrometer out of your grow area and set them up in a neutral area (outdoors, in the shade). Now all you have to do is compare the actual RH with whatever your devices say, to find out which one is more accurate.
Click to expand...
Thanks. Think I'll split the difference.:-|
 
hotrodharley

hotrodharley

Well-Known Member
Use a second hygrometer exactly like the one you have now. Check side-by-side. If they agree go with the cheapos. Tech isn't always better or more reliable.
 
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Whybotherwithyou2

Active Member
Is your hygrometer right next to the dehumidifier? That will also cause a difference, if they ate spread apart from each other. A dehumidifier draws the moisture out so it would stand to reason it's built in hygrometer would vary from one across a room.
 
J

jerichojews

Well-Known Member
Whybotherwithyou2 said:
Is your hygrometer right next to the dehumidifier? That will also cause a difference, if they ate spread apart from each other. A dehumidifier draws the moisture out so it would stand to reason it's built in hygrometer would vary from one across a room.
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There doesn't seem to be much variance when I place it different places in the room. The only thing that changes is the temperature when I place it under the lights.
 
SOMEBEECH

SOMEBEECH

Well-Known Member
jerichojews said:
There doesn't seem to be much variance when I place it different places in the room. The only thing that changes is the temperature when I place it under the lights.
Click to expand...
Might want to try a little patince mine does the same but after a few minutes its RT.
 
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