Topic: Barani pro passive shield

[CW2274]

Well switched the Davis FARS to stock and within 2 minutes fan died

[jerryg]

 

[jerryg]

high and low for today, windy today average wind 7 mph average gust 20 mph pro shield with top plate min 76.8/max 96.6 fars min 77.1/max 97.2 standard shield without top plate min 76.7/max 96.6  Nothing like wind to equalize things.

[openvista]

Just as a somewhat related aside, I've had several clear days/nights here recently. My 7714 passive shield and 7755 active shield perform indistinguishably, even in light 10m winds (1-3mph). Highs & lows are within a few tenths. One wrinkle has been some very thin smoke high up in the atmosphere, not enough to reduce visibility and undetectable most of the time except on satellite. According to the CRN station about 25 miles away in Chatham, today we reached a max radiation value of 748 Wh/m2 (yesterday: 797, Friday: 734).

Again, the 7714 only performs this well on my property when raised to 20ft. Down low it can run up to 4+ degrees warmer due to insufficient breeze. Just FYI, it's on a south-facing eave mount just over 6ft above the ridge line of my garage.

In other words, in moderate insolation conditions, at least, the passive shield performs identically to the FARS with even the slightest of breezes, and the FARS performs well despite what is apparently a significant siting disadvantage.

[CW2274]

In other words, the passive shield performs identically to the FARS with even the slightest of breezes, and the FARS performs well despite what is apparently a significant siting disadvantage.

Granted, semantics, but I think your FARS is not at a disadvantage, it's sat where it's suppose to be. The passive shield has the advantage because it's sat where it's not suppose to be.
However, point taken, good passive with a breeze = good data.

[openvista]

In other words, the passive shield performs identically to the FARS with even the slightest of breezes, and the FARS performs well despite what is apparently a significant siting disadvantage.

Granted, semantics, but I think your FARS is not at a disadvantage, it's sat where it's suppose to be. The passive shield has the advantage because it's sat where it's not suppose to be.
However, point taken, good passive with a breeze = good data.

The FARS is sheltered from winds from the NE to the S (about 150 degrees) and too close to reflected heat sources (pavement mostly). You put a passive shield there and it goes berserk. Cooling lake breezes comes from the E and the passive can't reach them down at 2m. But up high....

[jerryg]

Update todays min/max  pro shield 75.8/96.6  fars 75.8/97.8 no standard shield today was moving it around. Wind was light in am then moderate in the afternoon to windy with seabreeze coming in. Sky was partly cloudy today.

[jerryg]

Update min/max for today  pro 75.1/100.0  fars 75.4/100.9  standard 75.3/100.3  winds today were calm to light all morning then light in the afternoon and breezy with seabreeze around 4 pm and sky was basically sunny a few fluffy clouds at times.

[jerryg]

Heck i am not declaring anything just showing results in my location, i am not a scientist or anything else just a weather nut and i don't have access to anything but what i see. You can get better stuff from the makers home page with studies, my report is just general back yard stuff and take it or leave it.

[ValentineWeather]

I'll post some graphs later for PRO/FARS comparison, waiting for the peak temps to end.
I'm at a much less windy area vs Jerry so my data does look different.

I did install my second PRO at remote site today. Data is here: Went in service at 15:19- 68°.
 https://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=E7498

This is the intown station for compare and airport 1.3 mi.
Town: https://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=E3958&unit=0&timetype=LOCAL/

Airport: https://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=KVTN&unit=0&timetype=LOCAL/

[jerryg]

Wow two pros, i am impressed lol. Makes me feel less like a nut  . I don't know if i would travel around to set  it up at a remote site, still jealous of those temps, man after a 100 degrees today i felt much cooler just looking at your temps and thinking how great it would be to have to put on a jacket to go outside 

[ValentineWeather]

Hazy day, few thin clouds, wind on light side but not dead still either.
We have 90's in forecast this weekend again.

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[openvista]

Hazy day, few thin clouds, wind on light side but not dead still either.
We have 90's in forecast this weekend again.

Randy, is the FARS still running the AC fan?

[ValentineWeather]

Hazy day, few thin clouds, wind on light side but not dead still either.
We have 90's in forecast this weekend again.

Randy, is the FARS still running the AC fan?

I switched to stock solar unit.

[ValentineWeather]

I corrected the wind graph. Earlier was TX2 which is 30'.
Correct 8' is with FARS unit on TX3.

[openvista]

It's our first breezy sunny day with average wind speeds 5-6mph and gusts to 15mph. I'm seeing a pretty consistent pattern: the 7714 is about a degree cooler than the FARS.

Highs so far (2:30PM EDT):
76.2 (7714)
77.4 (FARS)

It's been a partly cloudy all day. Max solar radiation 795 Wh/m2 (in Chatham 25 mi away; the entire Midwest is under a dome of high pressure).

Lows are always within a tenth or two as both shields converge at night.

Yesterday, during a windy, cloudy day I was seeing about 0.5F difference most of the day with the passive running cooler.

It seems on calm, sunny days sensor overheating can dominate all other factors primarily on passive shields. On windy, sunny days the differences must hinge on shield material and configuration rather than air movement. I'm still wondering if replacing my FARS with new plastic would yield a better outcome.

[CW2274]

76.2 (7714)
77.4 (FARS)
On windy, sunny days the differences must hinge on shield material and configuration rather than air movement.

How about the fact that your 7714 is 20' in the air, isn't it?

[ValentineWeather]

I'm seeing the pro superior with a 3-5 mph wind at shield level, all other shields including FARS,
range is (.3) to (.9)F difference. Field level anemometer moved to transmitter #6 standard.
Snap shot.
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[dendrite]

I’ll wait for your graphs. You’re back to the stock fan, correct?

[ValentineWeather]

All stock on Davis FARS. Clouds rolled in as you can see on solar, plus sun soon gets behind trees which messes up test because some shields are in sun others not,,,, making one shield look better than other.  I switched 8' wind to Standard #6 to clean up area so I could mow between shields and not move cables. 
These are the best shields so for clean comparison only including best two.

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[jgentry]

I'm seeing the pro superior with a 3-5 mph wind at shield level, all other shields including FARS,
range is (.3) to (.9)F difference. Field level anemometer moved to transmitter #6 standard.
Snap shot.
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Noticed with the pro that the DP is sometimes 1° cooler than the others

[CW2274]

These are the best shields so for clean comparison only including best two.

Granted, early, but are you gleaning that the stock fan is under performing compared to the a/c fan?

[ValentineWeather]

I'm seeing the pro superior with a 3-5 mph wind at shield level, all other shields including FARS,
range is (.3) to (.9)F difference. Field level anemometer moved to transmitter #6 standard.
Snap shot.
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Noticed with the pro that the DP is sometimes 1° cooler than the others

Could be.... The difference I see in temperature with this little amount of wind is very small.
Jerry see's larger difference as winds get up. Still haven't had a real windy day to test.

[openvista]

76.2 (7714)
77.4 (FARS)
On windy, sunny days the differences must hinge on shield material and configuration rather than air movement.

How about the fact that your 7714 is 20' in the air, isn't it?

True. This could very well go back to siting.

Reflected/emitted radiation is more of a factor during the day. That's felt more near ground level. More specifically, there's a fair amount of pavement closer, both horizontally and vertically, to the FARS (within 25ft in two directions) and it's more sheltered down there so the heat can pool for a bit longer before being replaced by cooler air.

The issue today was felt most when radiation was strongest. Comparing the average temperatures spanning the 2 hours straddling solar noon (12:52PM - 2:52PM local time), I see a 0.81F difference with the 7714 coolest.

In the hour preceding the high temp (4:40PM - 5:40PM), the avg difference was 0.23F with the 7714 still cooler even though it was 0.1F higher for the daily max than the FARS.

Given that I'm not seeing large variances in highs and lows, I'd still defer to the 2m FARS shield.

[jerryg]

Unscientific update  sky partly cloudy winds light, calm in am picking up to 7 to 10 mph. pro 72.8/99.4  fars 72.8/100.4  standard 73.2/100.6