Page 1 of 1

Cronic low dew point from my WMR968/Meteohub

Posted: Fri Dec 05, 2008 8:54 pm
by kalib897
I have a chronic problem where my WMR968/Meteohub station is reporting low dew point values. My temperature, humidity, and barometer readings are spot on compared to surrounding stations and CWOP analyses but the dew point is always off.

What can I check, calibrate etc to attempt to correct ? Im running Meteohub v3.2 on an NSLU2

Thanks

Re:Cronic low dew point from my WMR968/Meteohub

Posted: Sat Dec 06, 2008 2:53 pm
by admin
As dew point can be calculated from temperature and humidity, this sounds strange to me. Could you please give an example of a sensor's temp/hum/dew reading where dew seems to be too low?

Are the values Meteohub shows in line with values the wmr-968 console displays?

Re:Cronic low dew point from my WMR968/Meteohub

Posted: Sat Dec 06, 2008 5:33 pm
by kalib897
I have always had an issue with this station tahat the humdity sensor reports low. I adjust that via scaling on Meteohub application. That works fine but the dew point reading is always low. Perhaps the scaling is not being accounted for in the calculation.

Here is a current reading
temp = 75.4
humid = 55%
dew = 42.8

WMR968 console and Meteohub comparison is fine

Re:Cronic low dew point from my WMR968/Meteohub

Posted: Sat Dec 06, 2008 6:42 pm
by admin
Meteohub takes the values as they come from wmr969, which reports all three values.

I found these calculators, which also indicates that your dew point at given temperature (75) and humidity (55%) should be about 58 instead of 43.
http://www.hpc.ncep.noaa.gov/html/dewrh.shtml
http://www.humidity-calculator.com/index.php

I checked with my wmr928, which looks ok:
temp 5.4°C, hum 98%, dew 5.1°C

Has anyone an idea what kalib897's wmr968 is doing wrong?

Re:Cronic low dew point from my WMR968/Meteohub

Posted: Sat Dec 20, 2008 2:44 am
by bobball
I've started getting low humidity readings on my 968, but the console appears to be reflecting the sensor. It may be a known problem, since a tech support at Oregon had a step by step means of dealing with it:
1. Remove battery from solar panel and disconnect,
2. remove battery and power from indoor unit.
3. in solar panel are two sets of batteries. Remove. Leave out a min of 6 hours. then replace, but leave battery covers off.
4. then separate sensor and console by 7 feet.
5. press reset button on solar panel first then press reset btton on indoor display.
Have I done it? No. Had outpatient surgery and a few inches of snow since I got the directions. I have a different sensor from Radio Shack, somewhat compatible with the console and perhaps made by Oregon, with the same problem. She speculated a similar fix would work.

Re:Cronic low dew point from my WMR968/Meteohub

Posted: Sat Dec 20, 2008 7:29 pm
by kalib897
I got the same response from Oregon Scientific but the problem persisted. I gave up and bought a new Davis Vantage Pro 2 system. Just installed it yesterday and no more problems.