Author Topic: A Comparison of Solar Radiation Shields  (Read 6901 times)

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Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #25 on: May 20, 2015, 02:17:41 PM »
The Davis FARS is known to be a poor performer anyway.

I disagree. Its well designed just needs a better fan to compete with RM Young types.
Randy, the Aviator is my father in 1963 with his Indian bike

Offline JCA433

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Re: A Comparison of Solar Radiation Shields
« Reply #26 on: May 20, 2015, 02:22:39 PM »
I was thinking of building a Stevenson screen to test.  The problem here is hurricane risk and all the weather hardware gets blown away. I had a horrific experience with hurricane Andrew in 1992 with a lot of damage.  My neighbor filled his boat with water and the wind was so strong it still got blown away.

Offline kcidwx

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Re: A Comparison of Solar Radiation Shields
« Reply #27 on: May 20, 2015, 02:23:46 PM »
What is your opinion of the Young shield?  What size fan does it have?  I have never purchased Young weather instrumentation.    Davis seems to be a very popular brand.

I'm not sure what size the fan is but more importantly the flow rate is anywhere from 5 m/s to 11 m/s of air depending on the temperature sensor size. It feels like a mini vacuum when you put your hand by the air inlet tube. It's been running for 8 years now with no troubles. It's been an excellent unit. I do clean it out every spring. The top flips open so it's easy to clean out in the field. Here's some photos of it just before I cleaned it out a couple weeks ago.


You can see the hinge where the top cap flips open for ease of maintenance.


Top flipped open showing the fan and power cable.


Top flipped open showing bottom section. This is the temperature sensor cable.
Sensor is about 3 inches down in the tube. You don't need to loosen the cable clamp
to pull the sensor out. Just lift the cable and the cable clamp ring slides out of the cylinder.


« Last Edit: May 20, 2015, 03:21:34 PM by kcidwx »
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Offline JCA433

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Re: A Comparison of Solar Radiation Shields
« Reply #28 on: May 20, 2015, 02:26:21 PM »
Is it wireless?   Is it powered by solar panels?

Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #29 on: May 20, 2015, 02:34:31 PM »

kcidwx would the RM young fit one of the Davis VP2 sensors inside?
« Last Edit: May 20, 2015, 02:44:32 PM by ValentineWeather »
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Offline CW2274

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Re: A Comparison of Solar Radiation Shields
« Reply #30 on: May 20, 2015, 03:33:47 PM »
Is the Davis FARS ASOS quality, prolly not, but still a lot better than the bottom feeders perpetuating the WX world.
The Davis FARS is known to be a poor performer anyway.

I disagree. Its well designed just needs a better fan to compete with RM Young types.
Davis Wireless VP2 SHT31 24hr 67CFM FARS
RW Tipper w/ CoCoRaHS

Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #31 on: May 20, 2015, 03:51:16 PM »
Is the Davis FARS ASOS quality, prolly not, but still a lot better than the bottom feeders perpetuating the WX world.
The Davis FARS is known to be a poor performer anyway.

I disagree. Its well designed just needs a better fan to compete with RM Young types.

FARS is a must when I lived in the desert. I could see 4-5 degree difference on average with the unofficial test I did. Turn  fan on turn fan off.  :grin:  Anyway I think the design is really good but where it suffers is the solar fan just doesn't pull the air like a RM Young. Enter the cheap high air flow AC fan I now run.
Randy, the Aviator is my father in 1963 with his Indian bike

Offline kcidwx

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Re: A Comparison of Solar Radiation Shields
« Reply #32 on: May 20, 2015, 03:53:59 PM »

kcidwx would the RM young fit one of the Davis VP2 sensors inside?

I don't have a VP2. If you get me the sensor board dimensions, I can do a test fit and see if it would work.
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Offline kcidwx

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Re: A Comparison of Solar Radiation Shields
« Reply #33 on: May 20, 2015, 03:59:12 PM »
Is it wireless?   Is it powered by solar panels?

It's powered by an AC to DC wall wart.
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Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #34 on: May 20, 2015, 04:08:32 PM »
Thanks, maybe for future reference if does or doesn't work good information.  The board removed from the Davis mounting board not needed is 2 x 1 1/4 and the filter cap over sensor sets off set middle of board includes board thickness is 1 1/8 high x 7/8 x 3/4
Randy, the Aviator is my father in 1963 with his Indian bike

Offline kcidwx

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Re: A Comparison of Solar Radiation Shields
« Reply #35 on: May 20, 2015, 08:07:39 PM »
Thanks, maybe for future reference if does or doesn't work good information.  The board removed from the Davis mounting board not needed is 2 x 1 1/4 and the filter cap over sensor sets off set middle of board includes board thickness is 1 1/8 high x 7/8 x 3/4

Looking up through the inlet tube. No go for a VP2 sensor.  :-(  Inside diameter is 15/16"

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Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #36 on: May 20, 2015, 08:17:50 PM »
Thanks, I was afraid of something like that. The Davis FARS will do but was curious if the RM Young could be made to work.
Randy, the Aviator is my father in 1963 with his Indian bike

Offline kcidwx

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Re: A Comparison of Solar Radiation Shields
« Reply #37 on: May 20, 2015, 08:38:33 PM »
Here's when I was routing the power cable and sensor cable into the shield.



The fan



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Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #38 on: May 20, 2015, 08:53:23 PM »
Fan looks similar in size to what have in my Davis FARS.
Randy, the Aviator is my father in 1963 with his Indian bike

Offline CW2274

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Re: A Comparison of Solar Radiation Shields
« Reply #39 on: May 20, 2015, 09:00:23 PM »
Fan looks similar in size to what have in my Davis FARS.
Please share. Since my ISS is tough to reach to check the motor status, I may try your option, if not for the mere sake of better aspiration. =D>
Davis Wireless VP2 SHT31 24hr 67CFM FARS
RW Tipper w/ CoCoRaHS

Offline kcidwx

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Re: A Comparison of Solar Radiation Shields
« Reply #40 on: May 20, 2015, 09:40:58 PM »
Davis made an AC version of that FARS. I have one of them here. Nice unit! Too bad they discontinued it.
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Offline CW2274

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Re: A Comparison of Solar Radiation Shields
« Reply #41 on: May 20, 2015, 10:13:48 PM »
Davis made an AC version of that FARS. I have one of them here. Nice unit! Too bad they discontinued it.
Nice.
Davis Wireless VP2 SHT31 24hr 67CFM FARS
RW Tipper w/ CoCoRaHS

Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #42 on: May 20, 2015, 10:40:20 PM »
Fan looks similar in size to what have in my Davis FARS.
Please share. Since my ISS is tough to reach to check the motor status, I may try your option, if not for the mere sake of better aspiration. =D>

I use a small AC fan, remove 1 tab, you basically wedge it in and seal around with rope putty. Works really well, somewhere I have the mm fan size and more information I posted.

« Last Edit: May 20, 2015, 11:10:03 PM by ValentineWeather »
Randy, the Aviator is my father in 1963 with his Indian bike

Offline kcidwx

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Re: A Comparison of Solar Radiation Shields
« Reply #43 on: May 20, 2015, 11:01:05 PM »
Here's the one I have:

http://www.davisnet.com/product_documents/weather/spec_sheets/7750_spec.pdf

Still a crappy aspiration rate. Randy's modification is much better.
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Offline CW2274

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Re: A Comparison of Solar Radiation Shields
« Reply #44 on: May 20, 2015, 11:04:52 PM »
Fan looks similar in size to what have in my Davis FARS.
Please share. Since my ISS is tough to reach to check the motor status, I may try your option, if not for the mere sake of better aspiration. =D>

I use a small AC fan, remove 1 tab, you basically wedge it in and seal around with rope putty. Works really well, somewhere I have the mm fan size and more information I posted.

Or this one: Not sure of size now, http://www.amazon.com/gp/product/B009OXMZ3Y/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I think this may be the correct fan, I'll need to dig deeper.
Thanks! I see the pictured fan pulls over twice as much air as the other. I just measured my spare fan housing and it's approx. 104 by 38 mm.
Davis Wireless VP2 SHT31 24hr 67CFM FARS
RW Tipper w/ CoCoRaHS

Offline CW2274

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Re: A Comparison of Solar Radiation Shields
« Reply #45 on: May 20, 2015, 11:07:32 PM »
Here's the one I have:

http://www.davisnet.com/product_documents/weather/spec_sheets/7750_spec.pdf

Still a crappy aspiration rate. Randy's modification is much better.
Thank you. I think my aftermarket DC motor may actually out perform that.
Davis Wireless VP2 SHT31 24hr 67CFM FARS
RW Tipper w/ CoCoRaHS

Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #46 on: May 20, 2015, 11:09:27 PM »
Ok my notes say I have the 80mm. Problem is I purchased both and without opening shield I won't know for sure but leaning toward the 80mm now.
Randy, the Aviator is my father in 1963 with his Indian bike

Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #47 on: May 20, 2015, 11:22:23 PM »
Here was an old post about it when I was smarter.  :-) " I've modified my Davis VP2 FARS with an AC fan Cooltron FA8025B11T7-51. Very easy to do, if my calculations are close I'm pulling approx 5 m/s across sensor vs the 1.1 m/s with the Davis solar powered fan."
Randy, the Aviator is my father in 1963 with his Indian bike

Offline CW2274

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Re: A Comparison of Solar Radiation Shields
« Reply #48 on: May 21, 2015, 12:47:49 AM »
Thanks! I just found this one which I think you showed before http://www.productsforautomation.com/cooltron-ac-fan-115v-92mm-fa9238b11t796-p/fa9238b11t7-96.htm. It appears it may fit even better and draw twice as much air, but probably overkill.
Davis Wireless VP2 SHT31 24hr 67CFM FARS
RW Tipper w/ CoCoRaHS

Offline ValentineWeather

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Re: A Comparison of Solar Radiation Shields
« Reply #49 on: May 21, 2015, 12:54:48 AM »
I think its too big though.
Randy, the Aviator is my father in 1963 with his Indian bike