Rain gauge stopped working

[Lanzalot]

WH 1081 - only 3 weeks old. Pole mounted on roof. Not able to safely get up to it until it stops raining so no idea why at the mo.

It been raining on and off since 0600 (prob c.5mm - guess) but station showing 0.00 today. I have a feeling it has been underreading since new but cannot be sure.

Anyone any ideas? Or had similar problem?

PS. Just restarted Cumulus (1.8.7) to force it to download data from station and it immediately showed a total of 0.3mm for today (still far too little)

[Repairman77]

Hi, a couple of things you can check.

First take off the lid and check for spiders, etc. They seem to like to live in there and can jam it from working. (You need to make a cover from dressmakers net to keep them out).
Manually move the see-saw up and down and see if it registers on the console.

Then check the leads are plugged in securely.

If you have no luck there may be a fault with the unit.

Let us know how you get on and if you cure the problem.

Mike.

[Lanzalot]

Thanks for that Mike. Got up to it and could not find anything blocking it. The top holes seemed to have water across them (surface tension maybe) and it emptied as soon as encouraged a few large drops down the chute. Ran some water from a jug through in dribs and drabs and it emptied every time Also registered on console correctly each time within 1 min. So not really sure what was going on.

I will investigate to netting protection from spiders, etc as you suggest.

Cheers.

[steve]

Could it be that as you have it mounted on the roof, the wind is preventing the rain from settling in the rain gauge properly? The sides on the collector are very shallow.

[Lanzalot]

Yes very possible Steve. The pole is only 3ft high and on the corner of a flat roof (I know further from roof would be better) with a small (c.1ft) parapet. The danger is that mounting the rain gauge ON the flat roof (with the existing cable) the parapet might protect the gauge if the wind is in the wrong direction. I could always extend the wire of course to move the gauge right away from edge of roof. I may tackle this once I have painted the roof (next urgent job!)

[beteljuice]

... The pole is only 3ft high and on the corner of a flat roof ...

Is it "overhanging" the flat roof ?

I notice that you have had significant persistent wind. It is possible that updraft through the drainage holes has been strong enough to prevent light rain from falling through the funnel.

[skyewright]

The danger is that mounting the rain gauge ON the flat roof (with the existing cable) the parapet might protect the gauge if the wind is in the wrong direction.

Depending on how far from the parapet you can get the gauge that might not be such a bad thing.

Obviously you want to avoid an actual "shadow", but beyond that wind can be "A Bad Thing" for rain gauges. In addition to beteljuice's good point about possible up draughts, strong horizontal wind can cause rain to be blown over the gauge. Some windy sites take measures to calm the wind around rain gauges (e.g. see the bit about a turf wall in section 5.6 on this page). I also remenber reading a study of the relationship between rain gauge height and under reading, but I can't find the reference at the moment.

One of the things I didn't like about the Davis VP2 design was the combined rain gauge & temp/hum sensor, so I got a spare rain gauge base (much cheaper than I expected!) which allows the unit to be split and the rain gauge placed down at 300mm rim height.

A thing to watch out for if you do place the gauge on the roof is splashing - you might want to do something with the adjacent surface to reduce that?

[simonvfr]

I found that internal application of WD40 has discouraged the spiders and earwigs that stopped my gauge from working. And external application in the shallow funnel has much reduced the tendency for water to collect there rather than running through as intended.

[Lanzalot]

No its not overhanging. Its fixed to the inner corner of the parapet. So I dont think thats likely. Good suggestion tho. Thx

No rain today - and a very pleasant 20.5 C at the mo - so will have to wait till more to know if it was a glitch or an ongoing problem.

Thx re the advice on protecting from the wind using the parapet. Makes sense. I will choose right position once the roof is painted (couple weeks) so it can be permanent.

Also noted re the WD40. The water was beading on the gauge ramp (not good - would prob evaporate quickly here with wind + sun often comes out hard on heels of a shower!). Will do that now.

Thx to all for the help.

[Semmy]

There is also a product I use on my motorcycle visor that would achieve the same aim, it is called Rain-X. Easy enough to source as most Halfords stock it.

http://www.rainx.co.uk/products2.php

[Sneezy24]

Had a similar problem on my unit, found a 'dry' joint on the reed switch that senses the bucket tipping. Blob of solder did the trick!