Author Topic: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD  (Read 8741 times)

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Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #275 on: August 09, 2018, 04:11:28 PM »
I thought about using snips but was afraid the board may break rather than cut and didn't have a bad board left to practice on, good to know, less messy and faster.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #276 on: August 09, 2018, 04:12:19 PM »
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Earlier this week I received and set up the Davis 7714 shield with a 31 sensor. It's about 8ft away and 1.5ft lower than my FARS (whose intake is at 5' 2").

This is the 3rd calm, sunny day in a row. Temps in the 70s mainly. Winds <3mph (~1 m/s) at 30ft (virtually calm at ground level).   

I put some data into a spreadsheet and found that around solar noon the difference between the two shields averages around 3-3.5F, sometimes 4F or more (passive sensor running higher). Overall, the average daytime difference is about 2-2.5F. The only time the shields are within 1F during the midday and afternoon is when heavy clouds pass overhead.

The height differential between the shields may play some role. However, raising the shield a meter or so won't produce much additional wind because the measurement location (like so many backyard weather stations) is hemmed in by taller structures on multiple sides.

Overnight lows are a bit lower (0.5 - 1F) on clear nights in the 7714, but not enough to balance out the false highs. On nights when skies are cloudy and winds are greater than 3mph, the shields run within 0.5F of each other (within sensor's margin of error).

This is about the same performance as I was getting from the stock VP2 passive shield mounted in the same location. I'm hopeful, with just a bit more wind coming from a prevailing direction (rather than a sheltered direction), the 7714 will outperform the stock passive shield. Unfortunately, those conditions have yet to happen. And there's no end in sight to the days with 10m winds at or below 5mph.

WOW! Bad numbers there wonder why I'm getting much better results. My max has only been +2 but it was during swing and max difference was 1.6. Not great but all other days have been really good.
The Davis Pro now I was seeing similar +2-4 difference daily.
My shields are only few feet apart at same elevation could it be something to do with being painted black inside? I don't know if you want to but if you do the Krylon fusion has less odor than other paints I tested. Still there but faint, I think the Ultra Flat camo dark brown would work best.

Todays data looks great light winds and sunny.
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Randy

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #277 on: August 09, 2018, 04:33:47 PM »
Pictures of final position of shields and stuff.

Offline openvista

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #278 on: August 09, 2018, 04:35:50 PM »
WOW! Bad numbers there wonder why I'm getting much better results.

Because of your optimal siting, even light winds will be felt to some degree at shield level. Not so much in my location. It's pretty safe to assume I have calm winds during most of the test period near ground level. I've walked around out there several times, looked up and I've seen the cups slowly turning at 30ft, but felt no breeze standing next to the shield.
« Last Edit: August 09, 2018, 05:01:31 PM by openvista »
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Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #279 on: August 09, 2018, 04:37:58 PM »
As of now (3:50PM EDT), about 2 hours after solar noon (1:55PM local time), winds average 2mph at 10m, skies are clear. FARS temp: 69.1 & 7714 temp: 73.1. This is typical of what I've been seeing and may even worsen in late afternoon when the sun angle is more directly focused on the western side of the passive shield.
FARS rule. :-P ;)
I'm reporting this passive aggressive post.

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #280 on: August 09, 2018, 04:39:43 PM »
WOW! Bad numbers there wonder why I'm getting much better results.

Because of your optimal siting, even light winds will be felt to some degree at shield level. Not so much in my location. It's pretty safe to assume I have calm winds during most of the test period near ground level. I've walked around out there several times, looked up and seen the cups slowly turning at 30ft, but felt no breeze standing next to the shield.

If it's a new 31 did you remember to do the -.9 offset if using pre Jan 2016 transmitter. Only reason I ask is I have a mix of iss transmitters and have done exactly that before.  :-)
Randy

Offline openvista

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #281 on: August 09, 2018, 04:54:38 PM »
If it's a new 31 did you remember to do the -.9 offset if using pre Jan 2016 transmitter. Only reason I ask is I have a mix of iss transmitters and have done exactly that before.  :-)

Yup, I put the offset in at the very beginning (as I had an SHT15 in the stock shield before that).
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Offline dendrite

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #282 on: August 09, 2018, 04:56:57 PM »
WOW! Bad numbers there wonder why I'm getting much better results.

Because of your optimal siting, even light winds will be felt to some degree at shield level. Not so much in my location. It's pretty safe to assume I have calm winds during most of the test period near ground level. I've walked around out there several times, looked up and seen the cups slowly turning at 30ft, but felt no breeze standing next to the shield.

If it's a new 31 did you remember to do the -.9 offset if using pre Jan 2016 transmitter. Only reason I ask is I have a mix of iss transmitters and have done exactly that before.  :-)

Samething here...resorted to labelling the ISS covers "old" and "new" to keep things straight.
Good idea. It gets even harder to keep track when switching between 31s and 75s.

Offline CW2274

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #283 on: August 09, 2018, 05:16:36 PM »
As of now (3:50PM EDT), about 2 hours after solar noon (1:55PM local time), winds average 2mph at 10m, skies are clear. FARS temp: 69.1 & 7714 temp: 73.1. This is typical of what I've been seeing and may even worsen in late afternoon when the sun angle is more directly focused on the western side of the passive shield.
FARS rule. :-P ;)
I'm reporting this passive aggressive post.
:-$

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #284 on: August 09, 2018, 05:36:12 PM »
Pictures of final position of shields and stuff.

I think you need a couple more shields  :grin:
Randy

Offline CW2274

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #285 on: August 09, 2018, 05:48:59 PM »
Pictures of final position of shields and stuff.

I think you need a couple more shields  :grin:
:lol: Look who's talking... :lol:

Offline openvista

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #286 on: August 09, 2018, 06:04:40 PM »
Just processed my 1 minute archives in each shield from 10AM to 5PM today.

Results (avg wind 1.9mph at 30ft; clear skies during test period):

7755 avg temp: 69.7 (FARS)
7714 avg temp: 71.9 (passive)
Difference: 2.2F

Difference between high temps: 1.9F

Current conditions at 6:03PM EDT: 73.1 (FARS), 76.7 (7714) with 1mph wind.
« Last Edit: August 09, 2018, 06:18:52 PM by openvista »
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Offline openvista

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #287 on: August 09, 2018, 06:11:17 PM »
I should add that I have a custom AC fan in my FARS that generates 24 CFM or about 444 LFM (2.25 m/s).
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Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #288 on: August 09, 2018, 06:42:00 PM »
Here is a link to site that has some good pictures of the shields and explains how it works https://creativepool.com/jan-barani/projects/meteoshield-professional

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #289 on: August 10, 2018, 08:53:10 PM »
Added second sht31 sensor into 7714 to see if location made any difference inside shield. Didn't see anything, with both the same and .8 max difference from FARS. Another really good day for 7714.

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Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #290 on: August 11, 2018, 03:36:12 AM »
Started thinking about this for getting the cut down board on SHT31 inside when I placed the order for PRO Shield the larger adapter wasn't available 26mm only the 13-20mm. At the time never thought much of it thinking it was just the pipe diameter on bottom, inside the shield would be the same size but now I wonder.
Are these Pro shields all the same inside? What size adapter did you order? Something that has never mentioned if even relevant.  I asked this question to allMeto but haven't received anything back yet.
Thanks
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #291 on: August 11, 2018, 11:39:21 AM »
OK i am now running the 31 in the pro shield, it fits ok with the excess board removed so will watch it today and see how it goes. Everything looks good compared with the other sensors so far. It will be nice if everything goes well.

Jerry need to know what adapter you have. When I ordered the  option for 26mm was not available.
Do you know if the 20mm will work?
Randy

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #292 on: August 11, 2018, 11:41:16 AM »
My thought was it just allows you to put a slightly larger probe inside the shield without increasing the interior dimensions of the chamber. Could be there may be a slightly larger probe that is used that needs the slightly larger clamp. I am using the regular clamp and with it being 3/4 inch i just set the 31 sensor on top of the tube and sealed the bottom to hold it in place. Keep in mind that the cable coming off of the sensor is offset to one side so the sensor can not be put center on the tube, the larger tube might allow it to center up more but have no way of knowing that but it might.
« Last Edit: August 11, 2018, 11:46:02 AM by jerryg »

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #293 on: August 11, 2018, 11:54:02 AM »
My thought was it just allows you to put a slightly larger probe inside the shield without increasing the interior dimensions of the chamber. Could be there may be a slightly larger probe that is used that needs the slightly larger clamp.

Hope so. That was my original thought also about adapter but wanted to make sure.
I've got no response from them in 24 hours so just sent another email today asking for some clarity and explaining again my intentions of using shield is with Davis cutdown sensor so there is no confusion what shield I need, if they are actually different inside.
The Pro shield still hasn't shipped the standard did go out Thursday.
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #294 on: August 11, 2018, 07:33:55 PM »
Another stellar day for 7714 with double sensors recording same exact temperature +.4F warmer on high temperature, -.2F on low. Not greatest test day however with wind reaching 10 mph at 40' at times.


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Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #295 on: August 12, 2018, 04:42:31 PM »
Received email from allmeteo concerning the chamber size on the Pro Meteoshield. They are all the same 44mm inside sensor chamber. The adapter size only pertains to clamp size.
They said they may add to specs so those doing unconventional setups will know what they have.   
Randy

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #296 on: August 13, 2018, 06:50:45 PM »
Both Meteoshields came in Pro and standard.
I've had all 4 shields in service for about 30 minutes. Not best time of day because of developing shadows. What I see so far.  Wind is  currently around 4 mph with occasional gust to 15 mph at 30'.

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Randy

Offline jerryg

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #297 on: August 13, 2018, 07:02:36 PM »
Are you running the new 31 and any problems fitting it in the shield?

Offline ValentineWeather

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #298 on: August 13, 2018, 07:18:19 PM »
Yes all same SHT31, only stock filter in FARS. Others are my flat glue on (no VOC) cut down board custom job. LOL  :grin:
The standard shield is already black inside so no paint needed but looking like the 7714 is doing slightly better constantly now. Not jumping to conclusion however need a better low wind test day.

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Randy

Offline CW2274

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Re: Field study thermometer shields FARS 7755, Passive 7714, & new METEOSHIELD
« Reply #299 on: August 13, 2018, 07:25:17 PM »
The Pro is really looking like the real deal, especially for folks who don't want to mess with a fan (that won't be me).
It's obvious the Pro can handle it's own with a slight breeze, now the "no wind, lotsa sun" scenario is obviously needed for the "are fans obsolete" test. :-"