Author Topic: The Reliability of the SHT-31 Humidity Sensor & What Psychrometer Should I Buy?  (Read 53497 times)

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Offline andro700

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I was thinking about springing for it anyways. Since it has much better specs than the one I have now.

Thanks,
Chuck

Offline jgentry

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Noticed that the Davis EnviroMonitor can take I2C sensors

https://www.davisinstruments.com/product_documents/weather/EM-sensors.pdf
Davis Vantage Pro2. SHT-75. WU: KXALJEMI2 & KALTHORS2. CWOP/APRS: C6353 & E6358

  

Offline galfert

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WS-2000 & WS-2902A | Ecowitt GW1000 | Meteobridge (WeatherBridge)
WU: KFLWINTE111  |  PWSweather: KFLWINTE111
CWOP: FW3708  |  AWEKAS: 14814
Windy: pws-f075acbe
Weather Underground Issue Tracking
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Offline jerryg

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Update on new 31, we had three days of very humid weather. The first day the lowest humidity was 86% and went up to 95%, day two stayed in the low to middle 90's all day and the third day the humidity was in the upper 90's all day and night. The sun came out today and dry air moved in and the 31 had no wet bias at all had a nice smooth drop in humidity and tracked the other two stations with no problems seen. So first long period of humidity was a winner. Now just have to see if anything shows up in the long run.

Offline jerryg

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Another update sensor still working fine, had dense fog this am and sensor hit solid 99% and no sign of wet bias so far.

Offline CW2274

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Another update sensor still working fine, had dense fog this am and sensor hit solid 99% and no sign of wet bias so far.
This one you threw in the Easy Bake Oven, right?

Offline jerryg

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Yes it is, baking made it work much better.

Offline CW2274

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baking made it work much better.
I just use my climate. ;)

Offline andro700

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I ordered a new fan and batteries and SHT-31 sensor. Got them installed and offset the temp -0.9. My 24 hour fan was not working at all. So going to see how temps and humidity react with new sensor and fan. Like I stated before I had humidity saturation. The date on the old temp/humidity sensor was 2009. The one I installed had the clear podding.

Chuck

Offline Tornado12

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Im new here on the forum, and am having to replace my humidity sensor in my VP2 as mine started reporting bad data. Ive tried to track through this long thread to get some info but its so long. Anyone care to give me a synopsis of the SHT-31 sensor? Is this a bad sensor? Good sensor? is the reliability poor? Im coming into this blind. Looking at my historical data it seems my snesor began going bad just 3 months or so after I bought my VP2 brand new. It is a 2017 unit so it came with the newer SHT-31 sensor. It reports humidty 10-20% too low compared to other stations. Today its reporting 73% and airport 20 miles away reporting 95% . Rain is looming today so very humid and cloudy. My new sensor arrives tomorrow and I will be installing it. Trying to gain some knowledge that may be helpful.

Offline ValentineWeather

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Im new here on the forum, and am having to replace my humidity sensor in my VP2 as mine started reporting bad data. Ive tried to track through this long thread to get some info but its so long. Anyone care to give me a synopsis of the SHT-31 sensor? Is this a bad sensor? Good sensor? is the reliability poor? Im coming into this blind. Looking at my historical data it seems my snesor began going bad just 3 months or so after I bought my VP2 brand new. It is a 2017 unit so it came with the newer SHT-31 sensor. It reports humidty 10-20% too low compared to other stations. Today its reporting 73% and airport 20 miles away reporting 95% . Rain is looming today so very humid and cloudy. My new sensor arrives tomorrow and I will be installing it. Trying to gain some knowledge that may be helpful.

Humidity is only relative to the temperature so saying your humidity is running low doesn't give a full picture of what's really going on. Where is the dewpoint in relation to the airport?  Like I said these SHT31 sensors run higher than airports is my experience so if anything they have a wet bias. This was the reason I was asking for a link to your station.
Randy

Offline Tornado12

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Im new here on the forum, and am having to replace my humidity sensor in my VP2 as mine started reporting bad data. Ive tried to track through this long thread to get some info but its so long. Anyone care to give me a synopsis of the SHT-31 sensor? Is this a bad sensor? Good sensor? is the reliability poor? Im coming into this blind. Looking at my historical data it seems my snesor began going bad just 3 months or so after I bought my VP2 brand new. It is a 2017 unit so it came with the newer SHT-31 sensor. It reports humidty 10-20% too low compared to other stations. Today its reporting 73% and airport 20 miles away reporting 95% . Rain is looming today so very humid and cloudy. My new sensor arrives tomorrow and I will be installing it. Trying to gain some knowledge that may be helpful.

Humidity is only relative to the temperature so saying your humidity is running low doesn't give a full picture of what's really going on. Where is the dewpoint in relation to the airport?  Like I said these SHT31 sensors run higher than airports is my experience so if anything they have a wet bias. This was the reason I was asking for a link to your station.

As of right now.

Airport:
TEMP: 61F
Dew Point: 56
Humidity: 84%
Pressure: 30.12

Ambient Weather WS-2902 3 miles from my station:
TEMP: 64F
Dew Point: 59
Humidity: 85%
Pressure: 30.17

My Station:
TEMP: 64F
Dew Point: 51
Humidity: 64%
Pressure: 30.15


The airport is ~20 miles north of me, and a cold front is approaching with lots of rain. The temperature difference is accurate and is reflected by all the weather stations in a 60 mile radius. The humidity im reporting (64%) is a lot lower than everyone right now. Dew Point obviously a little off as well. So dew point/humidty are innacurate. My temperature however is very accurate and has had no issues from what I can tell.

« Last Edit: Yesterday at 11:25:21 AM by Tornado12 »

Offline ValentineWeather

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Im new here on the forum, and am having to replace my humidity sensor in my VP2 as mine started reporting bad data. Ive tried to track through this long thread to get some info but its so long. Anyone care to give me a synopsis of the SHT-31 sensor? Is this a bad sensor? Good sensor? is the reliability poor? Im coming into this blind. Looking at my historical data it seems my snesor began going bad just 3 months or so after I bought my VP2 brand new. It is a 2017 unit so it came with the newer SHT-31 sensor. It reports humidty 10-20% too low compared to other stations. Today its reporting 73% and airport 20 miles away reporting 95% . Rain is looming today so very humid and cloudy. My new sensor arrives tomorrow and I will be installing it. Trying to gain some knowledge that may be helpful.

Humidity is only relative to the temperature so saying your humidity is running low doesn't give a full picture of what's really going on. Where is the dewpoint in relation to the airport?  Like I said these SHT31 sensors run higher than airports is my experience so if anything they have a wet bias. This was the reason I was asking for a link to your station.

As of right now.

Airport:
TEMP: 61F
Dew Point: 56
Humidity: 84%
Pressure: 30.12

Ambient Weather WS-2902 3 miles from my station:
TEMP: 64F
Dew Point: 59
Humidity: 85%
Pressure: 30.17

My Station:
TEMP: 64F
Dew Point: 51
Humidity: 64%
Pressure: 30.15


The airport is ~20 miles north of me, and a cold front is approaching with lots of rain. The temperature difference is accurate and is reflected by all the weather stations in a 60 mile radius. The humidity im reporting (64%) is a lot lower than everyone right now. Dew Point obviously a little off as well. So dew point/humidty are innacurate. My temperature however is very accurate and has had no issues from what I can tell.

With a cold front approaching hard to tell from a snapshot what's going on. You can remove the ambient from the picture. That would be my last choice of a reference station.  Need a station link?
Randy

 

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