Author Topic: Humidity Issue with VP2  (Read 1576 times)

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Offline Tornado12

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Humidity Issue with VP2
« on: February 19, 2020, 02:42:34 PM »
Hello all. I joined the forums today to try and get some help on an issue I am having. I have used the forums for reference in the past but just as a reader. I am an average joe who has always been interested in weather. I have a VP2 that I've been running for just over 2 years now at my house. Lately however I've noticed an issue with my humidity readings. Ill lay that out here to see what some others think.

My humidity seems to always be reading a little low (10-20% low) compared to all the other weather stations around me. The inaccuracy seems to be greatest when the humidity is really high. I live in Florida so we have a lot of high humidity often. I started to really notice the issue when wunderground began not showing my station on the wundermap, and I was losing my little badge that signifies a good station with accurate uniform readings for like 5 days I think it is. During the day, like right now at 2:20pm my humidity is reading about 10-15% below everyone else, but I am dead on what weather channel and weather bug, and other "official sources" are saying, which tend to go off of the readings from a small regional airport about 20 miles north of me. So I wonder if I'm accurate and everyone else is wrong, or what the truth is here. I am below EVERY weather station on the wundermap within a 100 mile radius - several of which are other Davis units. Also of note is my Humidity seems to hit a ceiling and it wont go above it, which for all of February so far is 85%. Even in the middle of heavy rains, and at night, it will just stop at 85%. If I look back over the past 2 years and just look month by month at the highest recorded humidity level, it shows a pattern of steady decline of this maximum figure, as if the maximum it will register has steadily fallen starting just a few months after I installed my VP2. Just 1% or so drop off each month, but it is a steady decline to the current time. Its really weird. Yesterday I took my whole unit apart and cleaned it - removed the sensor and the little screen housing around it and cleaned it all, put it all back together. I thought perhaps the steady decline suggested something affecting the sensor - dirt, spider web, something. Cleaning it however has yielded no change. Today I ordered a new sensor and will install it and see what happens.

Many times I am much closer to the "official" humidity then other stations around me as reported by the local air port, but some of the units I am seeing on wundermap are good units, some of them run by big farming outfits and folks like Duke Energy, who I would put weight into their units and installation and therefore their accuracy. Is this just a case of a bad sensor? There just seems to be no consistency with how innacurate it is. Sometimes Its close enough it doesnt stand out, other times it looks like a real odd ball on the map, and many times it matches what official sources report while surround wunderstations are a good bit off from where me and the airport are reporting. I'm also curious about the very clear and uniform pattern of max humidity reading decline over the past 2 years. When I first installed the unit I had days where Id hit 100% humidity. Then about 3 months later max for the month was 99, then 97 a few months later, so and and so forth and now 85% is the max. In january I recorded 86% max. Not a single month in the 2 years deviates from this decline. Would love to get others thoughts on this.

EDIT: also for the record my Temperature is dead on the money with everyone else. No issue with temp at all
« Last Edit: February 19, 2020, 03:00:30 PM by Tornado12 »

Offline galfert

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Re: Humidity Issue with VP2
« Reply #1 on: February 19, 2020, 02:49:44 PM »
Everything you describe is typical. When you notice this you need to replace the temperature/humidity sensor.

https://www.scaledinstruments.com/shop/davis-instruments/parts/vantage-pro2-parts/temperature-and-humidity-sensor-parts/davis-7346-070-pro2-digital-temperature-humidity-sensor-sensiron-sht31/

Lucky you that you have a VP2. If it had been a Vue then you'd be SOL.
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Offline Tornado12

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Re: Humidity Issue with VP2
« Reply #2 on: February 19, 2020, 02:58:22 PM »
Everything you describe is typical. When you notice this you need to replace the temperature/humidity sensor.

https://www.scaledinstruments.com/shop/davis-instruments/parts/vantage-pro2-parts/temperature-and-humidity-sensor-parts/davis-7346-070-pro2-digital-temperature-humidity-sensor-sensiron-sht31/

Lucky you that you have a VP2. If it had been a Vue then you'd be SOL.

I have that exact sensor already ordered and on the way. I just find it odd that many days I will match the official humidity as reported by weather channel and others for my zip code. It really took me looking into the data closely to realize the issue.

For example right now : Most of the surrounding stations are between 62-68% humidity. I am however reporting 51% humidity. Weather channel is reporting 54% humidity - based on the air port. Im closer to the airports numbers than everyone else. Its just odd to me.

EDIT: also for the record my Temperature is dead on the money with everyone else. No issue with temp at all
« Last Edit: February 19, 2020, 03:00:22 PM by Tornado12 »

Offline Tornado12

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Re: Humidity Issue with VP2
« Reply #3 on: February 19, 2020, 03:43:04 PM »
I also have a question regarding the new sensor on the way. Where can I find the "manufacturer code" of my VP2 unit to know if I would need to offset the sensor or not in the console? My unit SHOULD have the new sensor already installed, as I bought in I think 2017, but I want to be sure. I understand the new sensor started going into units in 2016. Where can I find the manufacturing code to verify though?

Offline ValentineWeather

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Re: Humidity Issue with VP2
« Reply #4 on: February 19, 2020, 04:11:09 PM »
Normally the VP2 will read higher, than airport not lower is my experience. I wouldn't bother looking at WC it's not reliable. Find a nearby airport for comparison.
I would check and make sure you haven't accidentally put an offset on the humidity. Never exceeding 86% is odd unless you are in a desert. So it would be helpful if you gave the station location and link station if online.

Randy

Offline CW2274

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Re: Humidity Issue with VP2
« Reply #5 on: February 19, 2020, 04:37:42 PM »

Offline Tornado12

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Re: Humidity Issue with VP2
« Reply #6 on: February 20, 2020, 08:46:57 AM »
Where can I find the manufacturing code to verify though?
https://www.manula.com/manuals/pws/davis-kb/1/en/topic/find-the-model-mfg-code

Thanks for that. Mine looks good - checked it last night. New sensor arrives tomorrow. Will install it and see what happens. Was considering upgrading to the new tiping spoon rain gauge as well but have read some luke warm stuff on it on this forum.

Big rains are looming today here in Florida. Checking my humidity this morning im way off, even from the air port I tend to benchmark myself against that is 20 miles north of me. I am reporting 73% humidity. Airport is reporting 95% humidity. Surrounding weather stations are all 88% - 95% range or so. So a day like today I am clearly under reporting the humidity. Rain is a few hours away but its very cloudy today, very grey, rain is looming, humidity very high. This is when I see the biggest inaccuracy in my readings. I hate that I am only just now realizing the sensor has gone bad. From looking at historical data it appears it began going bad just 2-3 months after I bought the unit, but it was so subtle at first I didnt notice.
« Last Edit: February 20, 2020, 09:19:37 AM by Tornado12 »

Offline ValentineWeather

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Re: Humidity Issue with VP2
« Reply #7 on: February 22, 2020, 08:01:37 PM »
New sensor arrives tomorrow. Will install it and see what happens.

And?
Randy

Offline Tornado12

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Re: Humidity Issue with VP2
« Reply #8 on: February 24, 2020, 08:40:19 AM »
Had the new sensor in for a few days now. My numbers look a lot more like surrounding stations now. My humidity also the past several nights have went up into the 90%+ range where it had not gone in a year. I assume it is fixed, and is reading more accurately. New tipping spoon arrives today and will install it.

Offline Tornado12

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Re: Humidity Issue with VP2
« Reply #9 on: February 25, 2020, 01:18:41 PM »
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Just wanted to show this little graphic, as it highlights the decline of the sensor. This is from the past year, and only shows the HI humidity reading for each of the 365 days. I wish I could have expanded this to 2 years, as you would see the graph decline from 100% readings on down. This graphic however, with just 1 year, shows the decline from february 2019 to february 2020. By February 2019 the sensor was already showing problems, with no readings going above 92%. Starting in October you can see a much steeper decline. There are lots of rain days in here where humidity was easily 90% and above. November through January 2020 the maximum was 86% - nothing would measure higher, even in full rain storms. That number seemed to drop even lower just before I changed the sensor on February 21, 2020, to a maximum of 85%. We had a good rain day just a day before I changed the sensor and it only hit 85% that day, despite readings from reliable stations of over 95% humidity. Finally, at the tail end of the graph we see the big spike to 98% - which was another day long rain event that occurred right after installing the new sensor. So, the sensor wasnt drastically off, and is why it took me so long to realize that there was a problem. When I began noticing the Humidity never going into the 90%+ during rainy days I began to look deeper.
« Last Edit: February 25, 2020, 01:23:36 PM by Tornado12 »

Offline havtrail

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Re: Humidity Issue with VP2
« Reply #10 on: February 25, 2020, 06:41:26 PM »
That's a very instructive graph - you can see the decline in the max levels clearly.  - Rich K.
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Offline Jasiu

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Re: Humidity Issue with VP2
« Reply #11 on: August 08, 2021, 10:00:44 AM »
Happy to find this thread as I've run into the same issue with one of my VP2s.

I assume the manufacturing code I want is the one from the ISS, right? This is an inherited unit that I rebuilt a couple years ago and I put in a new ISS then, so I think the temp/hum sensor referenced here should just be plug-and-play.

Thanks!
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Offline Tornado12

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Re: Humidity Issue with VP2
« Reply #12 on: August 08, 2021, 11:43:56 AM »
Happy to find this thread as I've run into the same issue with one of my VP2s.

I assume the manufacturing code I want is the one from the ISS, right? This is an inherited unit that I rebuilt a couple years ago and I put in a new ISS then, so I think the temp/hum sensor referenced here should just be plug-and-play.

Thanks!

Got notified by email of a reply to this old thread of mine. yes, if you are having the problem I described above just buy a new sensor. It is 8/8/2021 today and I am still using the sensor I replaced with in my unit, and it has not failed in the same way the original sensor did. Ive seen no decline in it at all since installing it about a year and a half ago now.

Offline davidmc36

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Re: Humidity Issue with VP2
« Reply #13 on: August 08, 2021, 01:52:39 PM »
Happy to find this thread as I've run into the same issue with one of my VP2s.

I assume the manufacturing code I want is the one from the ISS, right? This is an inherited unit that I rebuilt a couple years ago and I put in a new ISS then, so I think the temp/hum sensor referenced here should just be plug-and-play.

Thanks!

https://www.manula.com/manuals/pws/davis-kb/1/en/topic/temperature-humidity-general

" If you’re unsure which version you have then please decode the Mfg Code for your ISS. "

Offline Jasiu

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Re: Humidity Issue with VP2
« Reply #14 on: August 08, 2021, 04:32:32 PM »
It's an AZ code ISS, so I think I'm all set with the latest T/H and no need for offsetting. Already ordered!  :grin:
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