Author Topic: WH40 sensor reading  (Read 173 times)

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Offline wxwol

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WH40 sensor reading
« on: November 27, 2021, 04:44:40 PM »
Hi Everyone,

I have been running my new station, configured around a GW1100 and FOSHKplugin, with everything running well under the technical point of view. There may however be an issue with the rain sensor, a WH40, which I think is reading rainfall somewhat too low.

At first I thought it could just be my feeling, as it is difficult if not impossible to estimate how much rain may have fallen at any given time. I even considered that my old sensor (now removed and recycled) may have overestimated however by looking at data from other stations in the vicinity I noticed that my station is almost invariably the one with the lowest reading. For example I have a 3mm reading for today at the time of writing and four station in the vicinity read 5.59mm (SE), 6.60mm (SW), 8.20mm (W), 7.90mm (NW) respectively. I know that rainfall can vary to some extent even between seemingly nearby places, however I can see that this variation is not that large among the other stations and it seems to be my sensor to be somewhat far from the mean values.

Has anyone experienced a similar discrepancy by using a WH40?


Offline Rover1822

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Re: WH40 sensor reading
« Reply #1 on: November 27, 2021, 05:05:05 PM »
You will find multiple topics on this. https://www.wxforum.net/index.php?topic=39166.0  goes on for 12 pages. I really do suggest you read through that, and subsequent postings on the subject (you may have to search). IMHO there is no really definitive answer, I have 2 WH40s, and a WH65. My WH40s agree very closely to my manual rain gauge, the WH65 not so much. You also have to think about the error level , and consider that.

I really recommend that you get a reputable manual rain gauge , situated as close as possible to the WH40. Then after having those readings to compare to, make a decision.
Ambient:WS-2000,PM 2.5 x2,WH31B x2,WH40E,WH31P
EcoWitt: GW1100,GW1000 x4,WH31 x2,WH57,WH51 x12, WH40,WH5360B,WN34S
Web Sites: WU, Ambient Weather , Ecowitt.net , Ecowitt.net (TEST)
Personal Sites: Weather Cam

Offline broadstairs

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Re: WH40 sensor reading
« Reply #2 on: November 27, 2021, 05:05:50 PM »
I have the WH40 replacing my old Davis VP1, sadly my Davis gauge had stopped working so I was unable to run them beside each other and I did wonder. However I do compare with another local station which is within 2 miles of me and today he says 12.3mm and mine is 14.8mm which includes some melted hail this morning. Now I know from experience we have  wide variations round here being a coastal location and I know sometimes it is tipping down here but 2 miles away it is doing nothing!

Do you know how close these other station are to compare with? Just to be safe make sure your gauge tips freely (after removing the battery). Occasionally my Davis could stop tipping if a spider got inside and spun a web round the bucket!

Stuart
Ecowitt GW1003 with ultrasonic wind gauge, lightning sensor and PM2.5 sensor.

Offline Rover1822

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Re: WH40 sensor reading
« Reply #3 on: November 27, 2021, 05:20:17 PM »
IMHO, do not compare to nearby stations other than for a "relative" rain feel. If wondering about accuracy, get a manual rain gauge and place it as close as possible to you rain measuring sensors.
Ambient:WS-2000,PM 2.5 x2,WH31B x2,WH40E,WH31P
EcoWitt: GW1100,GW1000 x4,WH31 x2,WH57,WH51 x12, WH40,WH5360B,WN34S
Web Sites: WU, Ambient Weather , Ecowitt.net , Ecowitt.net (TEST)
Personal Sites: Weather Cam

Offline wxwol

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Re: WH40 sensor reading
« Reply #4 on: November 28, 2021, 05:50:34 AM »
Thank you everyone.

The interior is clean, so I will buy a manual gauge and install it next to the WH40 to see if there is a large discrepancy. It will take me a while to come to a conclusion but I'll let you know how it goes.

 

anything