Vantage Vue - crazy temp/humidity!

[DanielF]

Something happened in the early hours of this (Wed) morning (no lightning that I'm aware of!) and my VV started reading crazy values for outside temperature and outside humidy (see attached graphs). All other primary readings appear to be normal.

Prior to the major hicup, the outside temperature seems to have 'flat-lined', or close to it. After several hours both T and H returned to more 'normal' readings, though the temp is still too flat (I have no independent check for the outside temperature, but I'm pretty sure it's not that steady!).

Anybody seen this sort of behaviour before? It's definitely the Davis station and not Cumulus, as the crazy readings (or '----') appeared on the VV console display too. Any suggestions on where to start looking?

[steve]

The temperature/humidity sensor on my VP2 fails every few years and I have to replace it; I know others who have to do the same (Dave Wheeler on Fair Isle has given up replacing his). They don't seem to like coastal climates (Davis pretty much admitted this when I spoke to them). An intermittent large negative temperature is the usual symptom in my case. So perhaps yours needs replacing.

[DanielF]

The temperature/humidity sensor on my VP2 fails every few years ... They don't seem to like coastal climates...

Steve,

Thanks for this info. I live right on the coast, and in strong winds get direct salt spray on the house, so looks like that will be my problem too.

I'll start searching for a replacement sensor. Once I've replaced it (I gather the temp/humid come as a single unit?) I'll pull the old one apart to see if it's fixable (e.g. corroded circuit board traces) for keeping as a spare.

[steve]

(I gather the temp/humid come as a single unit?)

It does on the VP2, I don't know about the Vue.

[DanielF]

Hmmm, the sensors appear to have returned to 'normal' operation after yesterday's fit (see today's graph - looks like the cold, windy spring day that it was)!

But I'm nervous about how long this will last, and so want to get a spare sensor if I can. The local Davis distributor won't even tell me if they're available, let alone sell me one, because my unit was bought from the USA and is thus 'illegal' in Australia. (But for less than half the price including freight, it's the poor man's way to go.) Of course he offered to modify my unit to make it 'legal', but at a cost at least as much as I could buy a complete new unit from the USA. And that's before he even talks about the cost of repair!

I guess I'll have to open up the existing sensor module and see if there's any obvious problem (e.g. circuit-board corrosion) that I can work on.

Anybody know of a source of Davis replacements parts (Europe, Asia, USA; I don't mind)?

[I'm going to start a discussion on the 'general' forum about what's the 'best' AWS for coastal environments (obviously not Fine Offset or Davis!), for next time I buy one (assuming I could afford a better one!).]

[steve]

I think this is what you want: http://www.archertradingpost.com/atp/in ... cts_id=124 - that link gives the discounted price.

I seem to remember that when I was last posting about my sensor and what Davis had said, someone suggested that Rainwise were better for 'salty' environments. But I don't remember any evidence being given to support this.

[DanielF]

I think this is what you want: http://www.archertradingpost.com/atp/in ... cts_id=124 - that link gives the discounted price.

Thanks Steve; excellent find! I've ordered one.

I'll look into the Rainwise AWS for future reference, and see if I can find some real-world coastal user reviews!

[Paragon]

I replaced my VV temp-humidity-wind speed sensor recently when the outside humidity fell to 30% when it was raining, which Cumulus converts to a new record low for the dew point (one I remember was -42 deg. C).

Not sure you will be able to do anything to the "old" one. The PCB is sealed in a block of black rubbery compound. I could see nothing untoward from the outside in mine. I have kept it in the samples kit so I can remind myself what it looks like next time I have a problem.

Apparently these sensors are not particularly robust. The Davis agent in NZ said they do not like humid environments. Hu noze?

Graham
Tauranga, NZ

[DanielF]

I replaced my VV temp-humidity-wind speed sensor recently when the outside humidity fell to 30% when it was raining, which Cumulus converts to a new record low for the dew point (one I remember was -42 deg. C)...

Graham,

Might I ask how old your VV was when the sensor failed? And do you live right next to the ocean?

I must say I'm increasingly disillusioned with the Davis products - even my $100 Fine Offset stations lasted more than 2 years in this environment. The only reason I 'retired' the last one was because of some unidentifiable radio interference, so I was forced to try Davis because of their different frequency band.

I wonder if there are any other (affordable) brands of AWS that operate on a freq other than 433MHz?

[Paragon]

Might I ask how old your VV was when the sensor failed? And do you live right next to the ocean?

Hello Daniel,
I am about 8 km straight line away from the ocean at altitude 185 m. Age at sensor failure was c. 3 years. We get about 2500 mm rain p.a.

We are very humid. The inside of the ISS was damp when I opened it up. No visible water drops, but certainly not dry. The Davis agent told me these units don't do well in high humidity.

I tried a La Crosse before this one. It went back after a month or so because its software was not doing its job.

Perhaps for reliability it might be better if the inside was a more stable environment (humidity in particular) rather than having the tipping bucket pouring water through it. Then you get away from AWS to individual precision instruments like a proper weather station. The Vantage Vue is a complete compromise and quite expensive. But they are still inexpensive compared to more rigorous interpretations of weather recording standards.

All the best with your station.

Graham

[DanielF]

Graham,

Thanks for the quick reply.

I wouldn't feel so bad if my VV lasted 3 years, but it's less than 12 months old. But because I bought it from the USA (half the Australian price!) I can't claim under the warranty. I bought it 'trusting' that Davis was a 'good' brand, but sadly that has turned out not to be the case.

I live right on the ocean, with winds (gusts up to 140kph so far) blowing off the water leaving white spots (salt!) on the house windows. Not as humid as you seem to be (are you on the west coast?), but pretty extreme for a 'hobby' AWS. I had expected the Davis unit would do better than the el-cheapo Fine Offset units I had before.

Given that it's purely 'for curiousity' (especially wind speeds), it's hard to justify spending thousands on a 'real' weather station. Maybe I'll just 'build my own' one day, when I've got nothing better to do!

So far, since that day when it went crazy, the VV has been behaving again. Will be interesting to see how long it lasts before misbehaving again. Hopefully I'll have the replacement sensor by then.

[profzarkov]

Hi Guys
Seem to be having a similar problem - but just with the humidity:

uwfhumidity.JPG

The outside temperature is fine - this is a sister station to my own which is only a few miles away but another 600 feet higher - so it does get a lot of weather!

Maybe it needs a clean?

It's been there for over two years . . . is this about right for a David sensor failure?
Shame cos I recommended this kit to these guys (Yeo Valley http://ubleywarrenfarm.co.uk/index.htm) and it's performed brilliantly so far.

It's one of the highest and remotest stations around here. My own cheap kit (Watson W-8681) is still running after 4 years!

This is more of a pain as Cumulus works out the dew point and of course gets silly numbers (-43 today!).

Steve

[DanielF]

Steve,

Can't comment on the technicalities of your problem, other than to say it is conceivable that one could play up without the other malfunctioning – they are separate sensors, after all, even though mounted on the same PCB.

Strangely, my temp and humidity came good after a day of craziness and have been perfect ever since (one month so far). In the meantime I can recommend the supplier the Steve (Steve #1!) suggested – for their ridiculously low postage of $6.22 to Australia I expected the replacement sensor to come by boat, but it arrived in three weeks! I'm leaving the spare unit sealed in its plastic bag to prevent deterioration until such time as I need to use it.

I'll let you all know when the original fails again, as a measure of its volatility!

[profzarkov]

Thanks for that - will keep them in mind if the sensor stays AWOL.
We're having shedloads of weather at the moment, so I'll wait and see if it comes back up . . . can a humidity sensor have too much rain??

[martinu]

Hi Guys
Seem to be having a similar problem - but just with the humidity:

uwfhumidity.JPG

I've just started getting the same sort of symptoms with my Vantage Vue: temperature is fine but humidity intermittently falls to 1% and then rises to a sensible value of 40-50%: it falls every night and rises every morning.

I wonder whether it's caused by flying ants getting inside it: when I removed the baffles and the gauze shield around the sensor, there were ants everywhere. And because they are flying ants I can't rely on ant traps at the foot of the pole and sticky tape around the pole.

The last few days have seen a fairly consistent cycle:



This is several overlapping traces joined together.

In my case the Vantage Vue is about 8 months old. I live about 30 miles from the sea (so there's no salt-water spray) and the humidity up until then has been 60-80%, even during long hot dry sunny days.

By the way, the dew point is calculated by the Vantage, not by Cumulus: you can see it quoted on the VV console. Incidentally, all the values that Cumulus displays and records in the log files agree with those on the VV console, so it's not Cumulus that's at fault.

Either the sensor is playing up when the temperature gets colder or the humidity changes at night, or else the ants are leaving the safety of their "home" in the VV sensor unit during the day and returning at night - does anyone know how flying ants spend their days?