Popp Z-Rain accurancy problem

[benp]

Hello,
On monday, my Z-Rain recorded 128mm for 24h(midnight to midnight) when the nearest rain station recorded 81mm and 88mm (conversion factor 0.66).
Next day, I put a plastic bassin outside: 20.6mm when the z-rain gives 37.6mm (conversion factor 0.55).
Do you have similar problems or is this a particular problem of my z-rain or its installation?

[mgugu]

You should live in a very rainy region, 88 mm is a very huge value !
I own a Popp Z-rain too which gives reliable measurements.
First you could check if the device is in a free location whithout obstacles which could amplify the mesurement.
Also there is a "Meter Multiplier" parameter in configuration panel but you can correct only by integer values.
You could also try to make a "Refresh Node Info" in the configuration panel but be aware that the update may take more than 24h by default.

[benp]

88mm in 24h is a 30 years event in my region: a normal may is 122mm/month. But that event is good for calibration!
I have seen on that French forum:
https://forums.infoclimat.fr/f/topic/40 ... %C3%A8tre/
That a rain-meter calibration is not an easy thing. Some are calibrating several times a year.
I will buy a manual rain-meter this afternoon to try calibration.
I can't see an easy calibration procedure for the z-rain. The only way I can imagine is a virtual device and script unless somebody find something easier...

[benp]

I performed a calibration according to the french standard: a 400 cm² no-name rainmeter, copy of the too expensive certified for France SPIEA rainmeter. The standard rain surface to collect differs with country: 400cm² for France, 200 cm² for Switzerland , I don't know for the other.

20210516_160231bd.jpg (196.29 KiB) Viewed 2305 times

Here is the calibration graph. The black line is the raw line (without calibration and the blue line is calibrated line). The calibration coefficient is 0.709
! This is huge.

pluvio.png (31.78 KiB) Viewed 2305 times

You can find the excel file in the infoclimat link.

[mgugu]

Interesting to know, the measurement error is quite high. You could maybe report that to the Popp-rain manufacturer.

[benp]

I will try to move my rainmeter. Maybe, it's not far enough from the wall and roof...

[JackD]

Rain count can give very big differences between station/locations.
If you would measure 1 meter away from your rainmeter you already could have a big difference.

The Popp rain sensor measures with increments of 0.5mm/m2 rain. And is constructed this way to function properly.
If you want to see if your Popp rainmeter is working correctly you must calculate a given amount of rainfall, and pour this slowly into the Popp rainmeter and see if the theoretical value you calculated is roughly the same as it shows up in Domoticz. If this is correct, than your Popp is working correctly. (max. precision as stated in the documentation of the rain meter is 3,5 mm rain per
hour). If this all checks out the difference compared with the rain station at the other location is just that... the real difference in rainfall between your location and the other station.

You want to know the real rainfall at your location I would say, and not "calibrate" to run in line with a rainmeter at a other place?


For what I can see on your photo is that you will get a smaller rain count when the wind blows from left over the roof when it rains.
Put it a bit higher, slightly above the roof or at a other location with no restriction around it.

But perhaps I don't understand you correctly, in that case just ignore my remarks

[benp]

For what I can see on your photo is that you will get a smaller rain count when the wind blows from left over the roof when it rains.
Put it a bit higher, slightly above the roof or at a other location with no restriction around it.

No I have higher rain count with zrain, not smaller rain count: zrain count=1.41*manual count
That's strange but that's it.
I moved the zrain in the middle of my garden and the measure seem to be better. News soon at the next rain...

[ricdom]

I have seen exactly the same problem with accuracy. We had for our area quite a heavy rain over two days a few days ago. Zrain (mounted on an open, free place) reported 120 mm. A few meter from it was an empty bucket standing on a similarily open place. In the bucket there were 4.36 liters of water when it stopped raining and the diameter of the bucket is 25 cm. If I calculate correctly (4.36/(0.125*0.125*pi)) that would be about 89 mm which is not too far away from what the weather service meassured some kilometer away, 77 mm. They report 0.1-6.0 mm/hour. Zpopp on the other hand is way off which is very disturbing.

[benp]

I moved the zrain on the fence, far from the wall:

20210605_121814_2bd.jpg (189.22 KiB) Viewed 2232 times

There is no improvement.
It rained 43mm according to zrain and 30mm according to my manual pluviometer.
Base on 9 samples, my conversion factor is 1.40

I have seen exactly the same problem with accuracy. We had for our area quite a heavy rain over two days a few days ago. Zrain (mounted on an open, free place) reported 120 mm. A few meter from it was an empty bucket standing on a similarily open place. In the bucket there were 4.36 liters of water when it stopped raining and the diameter of the bucket is 25 cm. If I calculate correctly (4.36/(0.125*0.125*pi)) that would be about 89 mm which is not too far away from what the weather service meassured some kilometer away, 77 mm. They report 0.1-6.0 mm/hour. Zpopp on the other hand is way off which is very disturbing.

Your conversion factor is 120mm/89mm=1.35 base on 1 sample. We can say this factor is similar to mine.

[JackD]

My Popp Zrain at this time is also a bit off, and gives some strange behavior.
(See this topic viewtopic.php?f=6&t=36348 )
But it functioned properly until I updated Domoticz to Beta 13256, and now I run 13277 but my Popp Zrain is still not functioning well.

What Domoticz do you run?, perhaps it is not a acuracy thing but a recent problem with the Domoticz Beta, there has been some work done on rain-meters according to the Domoticz commits, or is this just a coincidence?

I moved the zrain on the fence, far from the wall:
20210605_121814_2bd.jpg
There is no improvement.
It rained 43mm according to zrain and 30mm according to my manual pluviometer.
Base on 9 samples, my conversion factor is 1.40

I have seen exactly the same problem with accuracy. We had for our area quite a heavy rain over two days a few days ago. Zrain (mounted on an open, free place) reported 120 mm. A few meter from it was an empty bucket standing on a similarily open place. In the bucket there were 4.36 liters of water when it stopped raining and the diameter of the bucket is 25 cm. If I calculate correctly (4.36/(0.125*0.125*pi)) that would be about 89 mm which is not too far away from what the weather service meassured some kilometer away, 77 mm. They report 0.1-6.0 mm/hour. Zpopp on the other hand is way off which is very disturbing.

Your conversion factor is 120mm/89mm=1.35 base on 1 sample. We can say this factor is similar to mine.

[benp]

My Popp Zrain at this time is also a bit off, and gives some strange behavior.
(See this topic viewtopic.php?f=6&t=36348 )
But it functioned properly until I updated Domoticz to Beta 13256, and now I run 13277 but my Popp Zrain is still not functioning well.

What Domoticz do you run?, perhaps it is not a acuracy thing but a recent problem with the Domoticz Beta, there has been some work done on rain-meters according to the Domoticz commits, or is this just a coincidence?

I am running domoticz 2021.1
I don't think there is a domoticz problem (I could have a look to the open zwave control panel). Rainmeters are difficult to adjust. Davis VP2 rainmeter owner have adjustement screw and need to adjust a least once a year to be within 5% error. We have 40% on zrain without adjustement...
See this topic (french) about Davis VP2:
https://forums.infoclimat.fr/f/topic/17 ... 2/?page=17

[commentator]

had a pop rain sensor in the past. It's crap. It died because it got wather inside just below the counter

[benp]

My previous rainmeter: oregon scientic life time was 3 years 6 month. I don't know its accuracy because I didn't look at it.
I don't know yet my z-rain life time but the correction factor is 1.4
I don't know what is the accuracy of other brand / models.

Post your correction factor here if you have it for your model!

The correction factor f can be found with the formula:
f=device measure/true measure

[benp]

Another strange behaviour of the Z-Rain:
2021-06-20 13:43:16 0.0
2021-06-20 13:46:08 0.71428571428571
2021-06-20 13:50:08 0.71428571428571
2021-06-20 13:54:18 1.0714285714286
2021-06-20 13:58:26 1.0714285714286
2021-06-20 14:31:39 1.4285714285714
2021-06-20 23:10:35 21.071428571429
Columns are time and precipitation (in mm) with dzvents with the device" z-rain" writen in a file.
What is strange here is 21.07 mm with no value between 1.42mm and 21.07 mm. It is a storm but I should have other values.
I don't know if this a z-rain or domoticz problem but I think it is the z-rain which don't update value.

Here is the dzvent for information:

Code: Select all

return {
   on = {
      devices = {'Pluviometre'},
      timer = {'at 00:00'}
      --timer = {'every minute'}
   },
   execute = function(domoticz, device)
        local RainMeter = 'Pluviometre'
        local R=domoticz.devices(RainMeter).rain/1.4
        local RR=domoticz.devices(RainMeter).rainRate/1.4
        
        if (device.isTimer) then 
            R=0
        end
        
        if domoticz.devices(RainMeter).lastUpdate.minutesAgo > 10 then
            RR=0
        end
            
        -- Opens a file in append mode
        local file = io.open('/home/pi/domoticz/backups/rain' .. domoticz.time.year .. '.csv', "a")
        
            -- appends a word test to the last line of the file
            file:write(domoticz.time.rawDateTime .. "," .. R .. "," .. RR .. '\n')
        
        -- closes the open file
        file:close()
       
   end
}

Do you have another reliable rainmeter reference to advise to me(zwave, rfxcom or zigbee)?

[benp]

More and more strange:
It rained 17mm June 23th to 24th in my manual pluviometer and nothing in my z-rain
The battery were 1.35V=55% in domoticz
I replaced the battery energizer ultimate lithium
More strange today: 4.5mm in the manual rainmeter and this in domoticz+z-rain:

zrain.JPG (19.53 KiB) Viewed 2183 times

[JackD]

This sounds exactly like the problems I had, see viewtopic.php?f=6&t=36348
In the end I thought my Popp Z-rain was defective. I replaced it with a new one and now it runs fine.
But your problem is exactly the same as what I had. That is to much of a coincidence.
So...looks like it could still be a Domoticz problem hidden deep away.
Some corrupted setting in combination with the unique ID of the Popp Z-rain sensor in Domoticz which goes wrong and you as a user can not get it right again. I Installed a brand new one with a new (physical)ID, this one works.

Which version of Domoticz are you running, I got my first troubles with Beta 13256, the did some work on rainmeters.... coincidence?


Perhaps some expert could take a good look at this problem, pretty please

More and more strange:
It rained 17mm June 23th to 24th in my manual pluviometer and nothing in my z-rain
The battery were 1.35V=55% in domoticz
I replaced the battery energizer ultimate lithium
More strange today: 4.5mm in the manual rainmeter and this in domoticz+z-rain:
zrain.JPG

[benp]

Which version of Domoticz are you running, I got my first troubles with Beta 13256, the did some work on rainmeters.... coincidence?

Domoticz is 2021.1
The negative value was after battery replacement but 17mm rain with no detection was before battery replacement.
I bought a TFA rainmeter(not received yet) but I am still looking for a reliable rainmeter...

[benp]

New erroneous value with my z-rain: 144899.1mm for July 13th!
Is this a domoticz or z-rain problem? Should I send back the z-rain?

I installed my TFA 30.3233.01: RFXCOM connection with pro2 firmware 1044 updated within domoticz.
I compared the value with my analog rainmeter.
The multiply factor is 2.5 to have the correct value (domoticz/edit device/multiply)
2.5 is very close to 2.54: the correction factor between cm and inch...
If somebody have the version with display ‎47.3005.01 and an analog rainmeter, we could know this is a domoticz or TFA rainmeter problem.

Note: the multiply factor for my z-rain is 0.71

[JackD]

Did you try to exclude the Z-Rain from your Z-Wave network, then reset it to factory settings, then include it again in your Z-wave network.

Would be nice if a programm wizz could take a good look at the TFA rain and Popp Z-rain implementation in Domoticz. Because I also think that under certain conditions things go wrong.