Temperature discrepancy?

I have 3 thermometers/hydrometers sitting next to each other ontop of my rack, all different brands and all giving me quite different readings. The temps are pretty close but the humidity's all over the place. I also have another accurite across the room that gives me similar stats as far as humidity goes. What do y'all make of this? How do I know which one is correct?

http://i11.photobucket.com/albums/a2...6/8319c67c.jpg

http://i11.photobucket.com/albums/a2...6/c34f2118.jpg


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There are numerous factors that could contribute to this but I would trust the one thats geared for herp keeping the most. Not all 4 of those look like herp thermostats to me.

Whats the accuracy in comparison to all 3 units? Do they all range in the accuracy differential? My current issue was the same as yours but with regards to temps, using the helix thermostat, accurite reading, and temp gun. they all produce a different output but are within each others accuracy range.

Next thing I would ask is are all the batteries within these units new if applicable just to ensure you have that area covered.

-Nick

The only way to really check is to use a salt test for the hygrometer (it works with digitals but it is hard on them, but so is ANY dust) thermometers the easiest way to check is multiple thermometers( I like to use 5+ and use the ones that are the same), or take one of know accuracy (traceable with low error) and check the others against it. Herpstat and helix both have accurate probes with in a degree according to the specs but at least for the herpstats I personally have tested 16 probes all with in 0.6º of accurate.

Ir guns have the same error margin of most cheap digital ones. +/-2ºF I own 3 accurites the best was 1.8ºF high and the worst was just over 5º low. the hygrometer was never good but was spec'd at +/- 20% so it is what ever it is.

I personally use a number of the cheapest digital probed thermometers I can find but lots of them and checked against each other and I give away of toss the ones that read off. (last batch I paid 1.05$ each and bought 30 of them) I really like the western instruments analogue hygrometer that is calibrate-able It is reasonable priced and accurate. I have 10 of them and have verified all with a salt test and found them to be with in 3%RH and they have held the adjusted amounts for 8 months but one which needed a re-adjustment.