Humidity Calibration
Posted: Tue 24 Oct 2017 2:36 pm
CWOP = AU084
I am using Cumulus release v1.9.4 (build 1099) with my Davis Vantage Pro 2 Wireless Weather Station. The station sits well over 100 feet from the nearest tree, house, road, air conditioner, or anything else. I have had the station up about 7 years and the Temperature/Humidity Sensor went out a couple of weeks ago. The temperature flat-lined at 45.1 degrees and the Humidity at 3%. So I ordered a new sensor and this past Saturday afternoon I replaced the sensor after a good cleaning of the station. The temperature is reporting very good numbers and not calibration is needed, but the humidity reading is off according to the Gladstone Family CWOP website. The Dew Point shows an Average dewpoint error over 24 hours of 21.2 °F, a daytime error of 9.2 °F, and a night time error of 31.0 °F. But looking at their graphs it showed a worse case of 3 degrees low and after changing the calibration last night it appears to be within a degree. The Relative Humidity shows a 22.8% difference but the chart shows very little difference.
Here is my question, I had changed the Offset to 6 and the Multiplier to 0 and I was still off. Last night I moved the Offset to 9 and I appear closer, but I am going below the standard at night and above the standard during the day. I am not real sure how to calibrate the Humidity Sensor properly to get me back in line. My old sensor was set at 3 and was in calibration with the Gladstone Family site for 7 years. But I need some help on how to calibrate the Humidity Sensor properly.
I am using Cumulus release v1.9.4 (build 1099) with my Davis Vantage Pro 2 Wireless Weather Station. The station sits well over 100 feet from the nearest tree, house, road, air conditioner, or anything else. I have had the station up about 7 years and the Temperature/Humidity Sensor went out a couple of weeks ago. The temperature flat-lined at 45.1 degrees and the Humidity at 3%. So I ordered a new sensor and this past Saturday afternoon I replaced the sensor after a good cleaning of the station. The temperature is reporting very good numbers and not calibration is needed, but the humidity reading is off according to the Gladstone Family CWOP website. The Dew Point shows an Average dewpoint error over 24 hours of 21.2 °F, a daytime error of 9.2 °F, and a night time error of 31.0 °F. But looking at their graphs it showed a worse case of 3 degrees low and after changing the calibration last night it appears to be within a degree. The Relative Humidity shows a 22.8% difference but the chart shows very little difference.
Here is my question, I had changed the Offset to 6 and the Multiplier to 0 and I was still off. Last night I moved the Offset to 9 and I appear closer, but I am going below the standard at night and above the standard during the day. I am not real sure how to calibrate the Humidity Sensor properly to get me back in line. My old sensor was set at 3 and was in calibration with the Gladstone Family site for 7 years. But I need some help on how to calibrate the Humidity Sensor properly.