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> Temperature calibration
aepca
post Oct 29 2006, 04:41 PM
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My VP1 is usually displaying temperatures higher compared to my mercury thermometer. I was thinking of recalibrating the temperature but I just wanted to check with you guys to see if its common to have to adjust the temp calibration. Should I leave the calibration on the factory settings and assume that is the most accurate or should I tweak them? Have any of you guys had to recalibrate your temperature?
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METARMan
post Oct 29 2006, 05:01 PM
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Does it display warmer temperatures all the time? Do you have the aspirated radiation shield?

I was getting warm temperatures as well. Even Davis admits that with the aspirated shield it may read a couple degrees higher than what standard thermometers will read during sunny conditions.
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aepca
post Oct 29 2006, 06:30 PM
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I have the standard radiation shield. The biggest difference in temperature is when its sunny with light winds but I guess that is to be expected when you don't have a fan aspirated shield. However my station still seems to be a little on the warm side all the time which is why I'm thinking of just calibrating it.
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°rjan
post Oct 30 2006, 06:12 AM
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aepca.......dont calibrate untill youve calibrated the mercury thermometer, you shall then use the fever-ice-method to display the accuracy at 37 degrees celcius and the perfect 0 celsius. if its allright then calibrate......remember, nobody says that the mercury is correct till its proven correct!!!!

°rjan
norway


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Richard Campbell
post Oct 31 2006, 07:40 PM
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Hi,

A good mercury thermometer is fairly expensive. Most of the ones in department stores are really not very accurate. The thermometers that come with sling or fan powered psychrometers are usually quite accurate (Bacharach makes very accurate thermometers.)

I have the aspirated shield with 2 batteries. The readings for temperature and humidity are dead on with an accurate psychrometer located in a nearby shaded place. Orjan's suggestion of checking the thermometer in ice water and in boiling water (with an allowance for elevation) is a good one.

I live in Northen California, the San Francisco estuary region, so I seldom experience little or no wind and high temperatures. I know that folks in very high temperature desert or tropic areas often run the fan with no batteries so that it really revs up when in direct sunlight (No power is diverted to charging the batteries). Personally, I like to have the fan run all night so that the temperature and humidity sensors can very quickly react to sudden changes. In particular, I like to have a quick warning if the temperature approaches freezing, although that hasn't happened in the last three years at my location. There seems to be a pronounced warming trend locally.

Richard
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aepca
post Oct 31 2006, 09:14 PM
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Thanks for the help. My mercury thermometer is by no means expensive, just a basic one you can find at a local store. I think I'll just leave my VP1 temp calibration alone since it probably is more accurate than my thermometer.

However when this weather station gives up I will be sure to get the fan aspirated shield for my next weather station. The outside temperature is the info I value the most on my station so I'm picky about it being as accurate as possible.
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Removed_Member_Joseph Toubes_*
post Nov 8 2006, 09:21 PM
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Anyone compare the Kestrel 4000 reading to the VP reading?

I went out and it was about 3 degrees lower on the Kestrel. I haven't changed anything, but slightly curious
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°rjan
post Nov 9 2006, 05:49 PM
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was it on the same height????????

°rjan


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Removed_Member_Joseph Toubes_*
post Nov 9 2006, 07:32 PM
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yes it was. What I did the second time ( tonight) Took the console outside with the Kestrel, put them at the same height as the ISS. In fact right beside it. then went inside for a while.. The outside temperature was about 1.5 degrees higher on the Davis and a 7% higher humidity as well.

Did notice that the outdoor temperature should equal the indoor sensor, but the response time is much slower on the inside.

So I am right now trying to get the inside temperatures to agree as well with the kestrel. Right now the console is 4.4F higher and the humidity id 10% lower than the kestrel. I could assume that might be close to true because the console has never been adjusted since the factory and I have had it for many years now. any way still waiting for thing s to stabilize a bit more before adjusting it
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IDaman
post Jan 22 2010, 05:24 PM
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QUOTE(aepca @ Oct 29 2006, 02:41 PM) *
My VP1 is usually displaying temperatures higher compared to my mercury thermometer. I was thinking of recalibrating the temperature but I just wanted to check with you guys to see if its common to have to adjust the temp calibration. Should I leave the calibration on the factory settings and assume that is the most accurate or should I tweak them? Have any of you guys had to recalibrate your temperature?


I have the VantagePro2, and get temp readings a bit higher year round. When I have ice, my sensor is showing 35 degrees or so. How do I calibrate the sensor?


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http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KIDOLA2
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dalecoy
post Jan 22 2010, 11:55 PM
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QUOTE(IDaman @ Jan 22 2010, 06:24 PM) *
I have the VantagePro2, and get temp readings a bit higher year round. When I have ice, my sensor is showing 35 degrees or so. How do I calibrate the sensor?


Read the VP2 Console Manual (Calibration).

If you have WeatherLink, it's also available under Setup.
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IDaman
post Jan 23 2010, 09:59 PM
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QUOTE(dalecoy @ Jan 22 2010, 09:55 PM) *
Read the VP2 Console Manual (Calibration).

If you have WeatherLink, it's also available under Setup.


Thanks.
"When all else fails, read the instructions." :-)


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