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Davis anemometer cups not moving in light wind

Posted: Sun 18 Sep 2016 12:18 pm
by RayProudfoot
Although the wind is very light here today I can see trees leaves moving and rose bush leaves rustling down at ground level.

But my Davis VP2 anemometer has rarely moved from 0 in the last 15 minutes. Here is my latest graph. http://www.cheadlehulmeweather.co.uk/trends.htm

It's very rare for my station not to record any wind movement in daylight hours. Mark's station 4 miles away is recording more wind than mine. It seems inconceivable that there could be a problem with a anemometer less than 3 years old especially the new more sensitive one from Davis.

I can't see anything obviously wrong. I'm concerned and until I can contact a friend I can't access it to check nothing is sticking. But what could be?These things are designed to last a long time aren't they?

Re: Davis anemometer cups not moving in light wind

Posted: Sun 18 Sep 2016 1:51 pm
by RayProudfoot
One thought that had occurred was that spiders may have entered the assembly and clogged things up with their webs. It has been a very warm September and I have spider webs on my bird feeder.

Will a good blow once low pressure moves in clear things out or am I looking at a disassemble and clean? :( Wind measurement is much lower than a station half a mile away.

Re: Davis anemometer cups not moving in light wind

Posted: Sun 18 Sep 2016 3:58 pm
by ConligWX
Took my Vantage Vue down a few weeks back and even the cups had a couple of spiders in them:) Spiders love to get into the smallest cracks to hide or nest. I've cleaned it all not but was amazed at the amount of spiders residing in the Vue.

The Vue is located at another site and I now have a new spider free VPro2 Plus up in the back garden ;)

Re: Davis anemometer cups not moving in light wind

Posted: Sun 18 Sep 2016 4:25 pm
by RayProudfoot
It does seem the most likely reason. My roof-climbing days are behind me so I'll have to hope an increase in wind sorts things out for me.

You'd think there were better places to bind a home than 30 feet up! :roll:

Re: Davis anemometer cups not moving in light wind

Posted: Mon 19 Sep 2016 10:14 am
by RayProudfoot
I think Mr Enormous Spider and his extended family must have upped sticks and left. Although the light winds today seem the same as yesterday the cups are moving okay. Little panic over.

I'm sure there are good reasons why anemometers cannot be made spider-proof. I'm just glad it looks like no remedial work is needed.

Re: Davis anemometer cups not moving in light wind

Posted: Thu 03 Nov 2016 12:54 am
by StormCapture
Davis anemometers are supposed to be sensitive to the lightest of breeze, usually 2km/h +,
I too also have this problem at times, when comparing it to my Fine Offset 1081 station, that one will read 5-6km/h and the Davis will read 0 even thought there is not much difference between the two in location, height wise yes with about 4m difference

My Vantage Vue anemometer will move but the console will still read 0.

Re: Davis anemometer cups not moving in light wind

Posted: Thu 03 Nov 2016 9:03 am
by RayProudfoot
4 metres is a big difference. You didn't say which is the higher. The Fine Offset I'm guessing.

There has been a large high pressure over the UK in recent days and winds have been very light. But the Davis seems okay. Mine is at 10 metres or very close.

Re: Davis anemometer cups not moving in light wind

Posted: Wed 14 Dec 2016 11:28 am
by StormCapture
The Davis sits the highest at 7.5m, will be 9m in the new year, 3.5m for the Fine Offset. The vane will move and the cable swing slightly in the lightest of breezes but he cups won't until there's sufficient momentum to get it going. Shaft gets cleaned every 6 months and cups cleaned also, tightened to the recommended tightness.

The Davis Vantage Vue stands at 2m on the tripods by Davis and that reads the lightest breeze also.

Re: Davis anemometer cups not moving in light wind

Posted: Sun 26 Mar 2017 11:31 am
by RayProudfoot
This problem has returned again. Coincidentally after a day of very little wind. Leaves on bushes moving but cups are reluctant to spin. I can see the vane moving but the cups are stationary.

My banner shows a high of 13mph but a few seconds later the speed drops to zero. I suspect spiders might be to blame as there is no obvious reason why they don't spin more freely.

Hopefully just a temporary problem, like last September.

Re: Davis anemometer cups not moving in light wind

Posted: Sun 26 Mar 2017 12:24 pm
by RayProudfoot
I've run diagnostics on my station and there have been only 9 instances where the reed switch was closed since midnight but 4311 where it was open.

So that begs the question if there have been so few closed states why is the speed stuck on zero so much?

Re: Davis anemometer cups not moving in light wind

Posted: Sun 26 Mar 2017 2:23 pm
by RayProudfoot
Having read this thread on the WX forum in the US I'm concerned this could mean the second anemometer is now starting to fail.

http://www.wxforum.net/index.php?topic=28845.0

Anyone else having Davis anemometer problems with the new Mk 2? This is just over 3 years old and given its cost I'm extremely unhappy if this one is starting to fail too. :(

Re: Davis anemometer cups not moving in light wind

Posted: Mon 27 Mar 2017 8:13 am
by RayProudfoot
This gets more confusing by the day. This morning the anemometer appears to be working okay again. Take a look at this graph showing average wind speed for my station (Cheadle Hulme) and Mark's (wilmslowastro).

The problem started around 6pm on Saturday 25th but seems to have corrected itself just before midnight.
WindComparison.png
We are covered by high pressure at present so winds are near calm. But watching the cups this morning they are definitely spinning freely. Has anyone else had this sort of problem and if so did it sort itself out?

Re: Davis anemometer cups not moving in light wind

Posted: Mon 27 Mar 2017 10:18 am
by RayProudfoot
I spoke too soon. Cups not moving again so clearly this problem isn't going away. Fortunately I have a spare which I can put up and having spoken to ProData they've asked if I can send this one back for them to check out.

There is clearly a problem with this anemometer as Davis have a replacement cartridge which oddly is not showing up on their own site but is on this US one. ProData were also unaware of this but are looking to get some. https://www.scaledinstruments.com/produ ... cartridge/

Re: Davis anemometer cups not moving in light wind

Posted: Tue 28 Mar 2017 5:40 pm
by RayProudfoot
Replacement anemometer now working. When my mate took the old one down we brought it indoors into a quiet environment and spun the cups. There is quite a bit of noise suggesting dirt or muck has entered the assembly and is affecting the bearings.

This photo shows a lot of muck inside which suggests there is a design flaw. No way should the inside look like that and the rust is quite concerning.
AnemometerBearings.jpg
This will be posted back to ProData tomorrow for them to inspect.

Re: Davis anemometer cups not moving in light wind

Posted: Wed 29 Mar 2017 5:08 pm
by Mapantz
wow - that looks as though it has just been found after lying in a muddy field for 6 months. :?

I hope it gets sorted quickly for you, Ray.