I have had a VP2 for a while now set up in an open space over grass, i am certain that the temperature screens heat up in the sunshine.

I have an old met office stevenson screen which was donated to me some time ago and as a test i have a wireless sensor in there too, on a cloudy day the readings are pretty much the same, however in direct sun the VP 2 heats up - currently both are in full sun the VP shows 12.5c the screen shows 10.9c

Has anyone else noticed this or has anyone used the FARS for the VP and seen different results?

 

Thanks.

 

 

I shifted mine to a sunnier but more exposed location in my garden last year and the temperature readings seem to be noticeably higher. I'm thinking of shifting it again, but there is never an ideal location. You can buy fan aspirated radiation shields for them. 

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I shifted mine to a sunnier but more exposed location in my garden last year and the temperature readings seem to be noticeably higher. I'm thinking of shifting it again, but there is never an ideal location. You can buy fan aspirated radiation shields for them. 

So it just goes to show that despite the £600+ price tag they are not that accurate which is probably why the offical observation sites still use the old screen method, lets face it if they were bang on accurate the met office could have obs sites allover.

Have yo any experience with the FARS?

 

I shifted mine to a sunnier but more exposed location in my garden last year and the temperature readings seem to be noticeably higher. I'm thinking of shifting it again, but there is never an ideal location. You can buy fan aspirated radiation shields for them. 

So it just goes to show that despite the £600+ price tag they are not that accurate which is probably why the offical observation sites still use the old screen method, lets face it if they were bang on accurate the met office could have obs sites allover.

Have yo any experience with the FARS?

 

No, I'm prepared to accept the possible issues with accuracy. It only seems significant to me in bright sunshine during the summer months. More of a concern to me is reliability as I'm currently on my second PCB and second temperature sensor. On my first PCB I had to replace the super capacitor. My second PCB board also now appears to be playing up with the last battery I installed discharging very quickly despite there being no evidence of the super capacitor leaking. I'm monitoring this at the moment just in case the fault was with the battery. 

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I shifted mine to a sunnier but more exposed location in my garden last year and the temperature readings seem to be noticeably higher. I'm thinking of shifting it again, but there is never an ideal location. You can buy fan aspirated radiation shields for them. 

So it just goes to show that despite the £600+ price tag they are not that accurate which is probably why the offical observation sites still use the old screen method, lets face it if they were bang on accurate the met office could have obs sites allover.

Have yo any experience with the FARS?

 

No, I'm prepared to accept the possible issues with accuracy. It only seems significant to me in bright sunshine during the summer months. More of a concern to me is reliability as I'm currently on my second PCB and second temperature sensor. On my first PCB I had to replace the super capacitor. My second PCB board also now appears to be playing up with the last battery I installed discharging very quickly despite there being no evidence of the super capacitor leaking. I'm monitoring this at the moment just in case the fault was with the battery. 

I have heard several issues relating to batteries failing prematurely, worrying when the old Maplin £50 one i have here as the second temp sensor in the met screen is 3 years old and has never failed.

I am convinced that direct sunshine inflates the temperature, even a low sun in winter.  I upgraded the VP2 i purchased end Nov 2005, with a daytime aspirated fan, actvated when direct sunshine hits the solar panels but this made little difference in lowering the temps.  From around early May to early October a Canadian Maple tree is in full leaf and shades my VP2 and VV for much of the morning.  Temperature readings are quite a bit lower than a nearby PWS and even Kenley Airfield, a Meto official site.  The reverse is true most afternoons, , at least comparing the Kenley readings, when any sunshine is directly on the VP2 And VV but the Kenley site may be in part/full shade.  As it is now home to a gliding club, access is limited so I'm not sure of their setup but a member ther did say it was an AWS.  I purchased a new temp/humidity unit in Febrary and this records 0.5c lower than the VP2 most of the time.  A sample from yesterday at 10:00 Local PWS 14.8c Kenley 12.9c Vantage Vue 11.8c New kit Temp 11.4c.  At 16:00 17.2c, 15.5c, 16.9c and 16.0c.  Dont have figures for the 'old' VP2 but as I say, random checks have shown temperaturs to be around 0.5c higher than the new kit.  By the way, my Wunderground site is ISURREYC5

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I am convinced that direct sunshine inflates the temperature, even a low sun in winter.  I upgraded the VP2 i purchased end Nov 2005, with a daytime aspirated fan, actvated when direct sunshine hits the solar panels but this made little difference in lowering the temps.  From around early May to early October a Canadian Maple tree is in full leaf and shades my VP2 and VV for much of the morning.  Temperature readings are quite a bit lower than a nearby PWS and even Kenley Airfield, a Meto official site.  The reverse is true most afternoons, , at least comparing the Kenley readings, when any sunshine is directly on the VP2 And VV but the Kenley site may be in part/full shade.  As it is now home to a gliding club, access is limited so I'm not sure of their setup but a member ther did say it was an AWS.  I purchased a new temp/humidity unit in Febrary and this records 0.5c lower than the VP2 most of the time.  A sample from yesterday at 10:00 Local PWS 14.8c Kenley 12.9c Vantage Vue 11.8c New kit Temp 11.4c.  At 16:00 17.2c, 15.5c, 16.9c and 16.0c.  Dont have figures for the 'old' VP2 but as I say, random checks have shown temperaturs to be around 0.5c higher than the new kit.  By the way, my Wunderground site is ISURREYC5

Interesting Pat, another case of poor radiation sheild then.

 

I shifted mine to a sunnier but more exposed location in my garden last year and the temperature readings seem to be noticeably higher. I'm thinking of shifting it again, but there is never an ideal location. You can buy fan aspirated radiation shields for them.

So it just goes to show that despite the £600+ price tag they are not that accuratewhich is probably why the offical observation sites still use the old screen method, lets face it if they were bang on accurate the met office could have obs sites allover.
Have yo any experience with the FARS?

I have had the FARS for several years on my VP2 station. It makes a massive difference. I also have a Stevenson screen sited right next to the VP2 with a standard spec mercury maximum thermometer. They are in a very sunny location in a south facing garden. The VP2 frequently records a lower maximum than the mercury thermometer. Usually though they are both within 0.2C of each other and record figures that are broadly in line with nearby official stations. My readings are always slightly higher but that is simply down to the non standard exposure as my house is not far away from the station due to my garden being quite small.

I would say that the expense of the VP2 is not worth it without the FARS because the readings are not that accurate. With the FARS the station is a very accurate and reliable piece of kit that in my view is well worth the money. The extra expense of the FARS is a must.

I shifted mine to a sunnier but more exposed location in my garden last year and the temperature readings seem to be noticeably higher. I'm thinking of shifting it again, but there is never an ideal location. You can buy fan aspirated radiation shields for them.

So it just goes to show that despite the £600+ price tag they are not that accuratewhich is probably why the offical observation sites still use the old screen method, lets face it if they were bang on accurate the met office could have obs sites allover. Have yo any experience with the FARS?

I have had the FARS for several years on my VP2 station. It makes a massive difference. I also have a Stevenson screen sited right next to the VP2 with a standard spec mercury maximum thermometer. They are in a very sunny location in a south facing garden. The VP2 frequently records a lower maximum than the mercury thermometer. Usually though they are both within 0.2C of each other and record figures that are broadly in line with nearby official stations. My readings are always slightly higher but that is simply down to the non standard exposure as my house is not far away from the station due to my garden being quite small. I would say that the expense of the VP2 is not worth it without the FARS because the readings are not that accurate. With the FARS the station is a very accurate and reliable piece of kit that in my view is well worth the money. The extra expense of the FARS is a must.

Thanks for that, FARS it is then

http://www.scaledinstruments.com/ formerly  Archer trading.

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http://www.scaledinstruments.com/ formerly  Archer trading.

Spooky Col!

Can you please let me know how it goes?

Cheers 

I know it cost £98 inc. delivery rather than £150+ so far.
But there will be about £25 customs to pay I expect.
I've bought things from them twice before, it will probably be here about Wednesday.

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Well I must say USPS are dog slow.
You'd wonder how it was possible for a package to take nine days to travel 343 miles from Jacksonville FL to Miami!
Maybe they send people out on foot with them in a shopping trolley?
It should be in the UK by Monday.
Admittedly it's only the budget shipping opton as there's nothing spoiling.

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Dear me, you really have to have deep pockets to purchase a VP and it now seems it is prone to significant errors!

You are probably better buying a mid-price station and building your own wooden radiation shield, thats what I did and even on hot, sunny days my readings are within 0.5c of the nearby MetO station.

Andy

 

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http://nymweather.blogspot.co.uk/2014/09/daytime-fars-fitted-to-vp2.html

Finally arrived this morning, more details in blog post above.

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Well I must say USPS are dog slow.
You'd wonder how it was possible for a package to take nine days to travel 343 miles from Jacksonville FL to Miami!
Maybe they send people out on foot with them in a shopping trolley?
It should be in the UK by Monday.
Admittedly it's only the budget shipping opton as there's nothing spoiling.

Takes a while for fat Americans to do anything! 

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