Author Topic: temp/hum sensor failing on 10-y old Davis ISS?  (Read 885 times)

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Offline metro750

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temp/hum sensor failing on 10-y old Davis ISS?
« on: July 23, 2018, 06:14:54 PM »
Hello everyone.  I have a 10-y old Davis weather station, a 6322C cabled integrated sensor suite that's connected to my computer via a weather envoy and I run Weatherlink 6.0 software.

Lately, the temp sensor seems to fail for an hour or so in the middle of the day.  I emailed Davis Support about it and they said that I should replace the sensor, or send it in for repair.  Now I can't get in contact with them.  My question is whether any Davis temp/hum sensor board will fit this ISS.  For example, Ambient Weather has this: Davis Instruments 7346-070 7346.070 Temperature / Humidity Digital Sensor Board for Vantage Pro2.  Will this work?

Thanks in advance!

Offline Forever

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #1 on: July 23, 2018, 07:10:52 PM »
That looks like the same part number listed on their site. https://www.davisinstruments.com/product/temperaturehumidity-digital-sensor-board-for-vantage-pro2/

If this is your first replacement in 10 years you're doing really good. I just ordered my 4th yesterday for my 10 year old station.

Offline metro750

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #2 on: July 23, 2018, 07:18:44 PM »
Thanks Forever.  I'm always confused when they describe parts as, e.g., for the Vantage Pro 2.

Yes, my first temp/hum sensor failure.  I had a couple problems with the rain gauge (reed switch), but nothing else.  Maybe being in a mild climate in California affects the failure rate?

Offline SnowHiker

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #3 on: July 24, 2018, 04:59:21 AM »
Just make sure that your station was manufactured after January 2006, as it says on the website.  If your station is only 10 years old that should be the correct sensor board. If your station was older than 12 years, before they came out with the digital sensor, your sensor would probably still be good.
« Last Edit: July 24, 2018, 06:02:06 AM by SnowHiker »

Offline dendrite

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #4 on: July 24, 2018, 09:11:35 AM »
It will work, but you will need to enter a temperature calibration offset for the newer sensor. Read on here...

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

Offline metro750

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #5 on: July 24, 2018, 10:39:23 AM »
OK, thanks.  I've ordered it and I'll post again after I get it and try to install it.

Thanks again for all the advice.

Offline metro750

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #6 on: July 29, 2018, 05:58:05 PM »
I replaced the sensor and didn't get any t/h readings at all on my Weatherlink software until I went through the station config setup again.  I didn't change any of the settings, just clicked through the "walkthrough" sequence.  After this, I went back and added the temp calibration (thanks Dendrite).

I referred to the 2-part video that Davis posted on youtube for replacing the sensor.  The only part that was a little tricky was reassembling the radiation shield in the correct sequence.  If anyone is doing this for the first time, I'd recommend taking photos of how the shield comes apart.  I completely disassembled mine to wash it and thought I noticed how it went together, but it was trickier than I thought.  Reassembling it on the ISS, it helped to have someone else hold the parts together as I threaded them on the 3 screws that go through the mounting plate for the rain collector.

I'm adding a few photos: old and new sensors, new sensor mounted on the radiation shield.

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Offline Mattk

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #7 on: July 29, 2018, 08:50:19 PM »
Appears you may have one of the very first units (7346.166H 08/08/2005) that was introduced after the 7346.029 that was used in the VP1 and first VP2 models (2005) was replaced with the 7346.166 (and its variants) which I believe is the first of the digital versions? Otherwise with a unit this old you may have been up for a new ISS?

Also the screw that supports the cable (clear support tab), don't tighten it down very hard at all as it will fracture the tab.     

Offline metro750

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #8 on: July 29, 2018, 11:42:40 PM »
The ISS was manufactured in August 2008 according to the manufacturing code printed on a label in the SIM housing.

And yes, I know this station is probably nearing the end of its service life.  But it has been quite reliable so far, except for the (relatively) minor failures that I mentioned.

Actually, my biggest problem is losing data during power failures, power failures that happen during big storms when I'd like to be collecting data.

Offline metro750

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #9 on: July 30, 2018, 12:38:56 AM »
@OldTeleMan, would this work with my setup (cabled ISS => weather envoy => network router => computer (weatherlink)
                                                                                                                                => Davis weatherlink network upload => weather underground

Would I connect the UPS between the electrical outlet and the Envoy?  Why don't the batteries in the Envoy retain my data during power outages?

Thanks for the advice! I guess I don't fully understand how these components work. 


Offline Mattk

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #10 on: July 30, 2018, 03:27:04 AM »
A cabled Envoy (or VP2 console) draws 10 times more power than the wireless versions so the internal batteries won't last long at all. In your situation in a storm then the #1 priority is to power the Envoy, which keeps the sensors alive and the logger running so the data backlog can be uploaded once the router and PC come back on line. Either a mains UPS or external battery setup.

Obviously if you are using a PC then you have a serial or USB logger which isn't as power hungry as a WeatherLinkIP so you save around and extra 100mA   

Offline metro750

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #11 on: July 30, 2018, 02:31:25 PM »
Thanks Mattk and Oldteleman, this is helpful.  I think someone else may have pointed this out to me in a previous thread, but I haven't installed any kind of backup power yet.  I'll seriously consider it before our next rainy season.  Those peak storms are exactly the ones you want to measure.

Offline tshattuck

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #12 on: September 20, 2018, 05:42:55 PM »
FYI
I am on my fourth temperature / humidity sensor for my 12 year old Vantage Pro2. I just replaced the last sensor, it only lasted 22 months, the sensor part number was Davis Part #6930. Davis has replaced the sensor with part # 7346.070.
The new sensor is supposed to have tighter temperature tolerances and will work with any Vantage Pro2 built from 2006 on. Each time the sensors failed it was always on the Dew Point side. Hopefully the new sensors will have a longer life cycle.
The biggest hassle is taking apart the fan aspirated radiation shield to replace.

A two to three year life cycle is not good, the product should be more robust. :roll: I do not live near a salt water environment so that's not a concern, I live in New York State so it gets cold in the Winter.

Keeping my fingers crossed.
 

« Last Edit: September 20, 2018, 06:41:39 PM by tshattuck »

Offline CW2274

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #13 on: September 20, 2018, 06:25:34 PM »
Davis has replaced the sensor with part # 7346.070.
If you're unaware, for older VP2's such as yours, the SHT31 requires a -0.9F temperature offset be applied into your console or software.

Offline tshattuck

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #14 on: September 20, 2018, 06:39:21 PM »
I am aware of the offset, I should have mentioned that in my post.
I am currently monitoring the temps of local weather stations, I have two stations that are within a mile of my station and they have the same readings. I will be monitoring for several days.

Thanks for the feedback.

Offline CW2274

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #15 on: September 20, 2018, 06:54:04 PM »
I am aware of the offset, I should have mentioned that in my post.
I am currently monitoring the temps of local weather stations, I have two stations that are within a mile of my station and they have the same readings. I will be monitoring for several days.

Thanks for the feedback.
Also, don't know if you've been following the SHT31 thread that's been "occasionally" :lol: mentioned here, but the 31 is a fantastic temp performer, but apparently Davis's manufacturing process tends to make the sensor have a wet bias for the dew point. Some are better than others, just something to watch for.

Offline tshattuck

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #16 on: September 20, 2018, 07:30:18 PM »
I wasn't aware of other issues with SHT31.

Thanks for the heads up.

Offline bill-e

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #17 on: October 09, 2018, 02:32:41 PM »
I just ordered an .070 temp sensor.  Does one add the -0.9 offset to the value that's already there or just enter it as the new offset?  I had a .166 sensor...well over a decade old and the first time it failed.

Offline CW2274

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #18 on: October 09, 2018, 03:44:46 PM »
I just ordered an .070 temp sensor.  Does one add the -0.9 offset to the value that's already there or just enter it as the new offset?  I had a .166 sensor...well over a decade old and the first time it failed.
Your statement makes it sound as if you already have a correction factor in your temp reading. If so, after installing the SHT31, I'd use only the -0.9F correction and see if it is where you want it before factoring your old correction back in, if indeed you had one. You may be satisfied with only the -0.9F.

Offline bill-e

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #19 on: October 09, 2018, 05:44:50 PM »
I just ordered an .070 temp sensor.  Does one add the -0.9 offset to the value that's already there or just enter it as the new offset?  I had a .166 sensor...well over a decade old and the first time it failed.
Your statement makes it sound as if you already have a correction factor in your temp reading. If so, after installing the SHT31, I'd use only the -0.9F correction and see if it is where you want it before factoring your old correction back in, if indeed you had one. You may be satisfied with only the -0.9F.
Actually I don't know if there is one already in there, cant tell since I already removed the bad unit.  I just thought that there may have been a factory default in there.  I'll check when I get the new one.

Offline CW2274

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #20 on: October 09, 2018, 06:15:36 PM »
I just ordered an .070 temp sensor.  Does one add the -0.9 offset to the value that's already there or just enter it as the new offset?  I had a .166 sensor...well over a decade old and the first time it failed.
Your statement makes it sound as if you already have a correction factor in your temp reading. If so, after installing the SHT31, I'd use only the -0.9F correction and see if it is where you want it before factoring your old correction back in, if indeed you had one. You may be satisfied with only the -0.9F.
Actually I don't know if there is one already in there, cant tell since I already removed the bad unit.  I just thought that there may have been a factory default in there.  I'll check when I get the new one.
All correction factors are put in through your console, the sensor has nothing to do with it.

Offline bill-e

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #21 on: October 12, 2018, 10:06:04 AM »
While waiting for my new sensor I decided to reinstall the old one to see if there was any correction factor.  Of course there wasn't since I had never entered one but the sensor has been working fine for two days now.

When I first took it out I left it out for about 10 min and reinstalled it and it was still showing 138 amd 100% Humidity so I assumed it was gone.  I left it out for about a day and a half before I plugged it in again and now it iw working accurately.

I don't dare send the new sensor back for fear that this will fail again so I think when I receive it I'm just going to connect it to the ISS and confirm that it works and then put it away for a rainy day.

Offline bill-e

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Re: temp/hum sensor failing on 10-y old Davis ISS?
« Reply #22 on: October 14, 2018, 03:59:42 PM »
I ended up installing the new .070 sensor and inputting the -.9 correction factor and the new sensor is tracking exactly the same as the old one when compared to the Bloomsky sensor which sits 3' from it.  I'll keep the still working .166 as a spare.

 

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