Topic: AC Case fan for 24 HR Davis FARS shield mod recommendation requests

[AWL]

Thanks. AWL how did the iss maintainence go?
Why did you change out sht?

Well.....The package with my new ISS plates was supposed to be here Friday. Tracking now shows it will be here tomorrow.
Plan is to change sensor and plates at the same time. Hopefully tomorrow afternoon???? The sensor was spiking high humidity especially on days over 90F. Shooting my dew point and heat index up there in world record territory!


Doug

[fkapp]

Any luck?

[fkapp]

Out of curiosity what does the stock davis solar powered fan on the 24x7 FARS cfm run when full charged?

[CW7491]

Davis used to list the full sun aspiration rate at 190ft/min. I’ve noticed more recently they’ve listed that now as the intake flow rate and have the sensor chamber flow rate at 500ft/min. With the sensor chamber diameter of 2.26”, if my math is right, that should work out to just under 14CFM.

Flow rates:
https://www.davisinstruments.com/product_documents/weather/spec_sheets/DS7714_6838_Rad%20Shields_Spec_Sheet.pdf

Sensor chamber diameter:
https://www.davisinstruments.com/product_documents/weather/spec_sheets/7755_spec.pdf

[fkapp]

Thanks for the help with the CFM calc.

I am going to be ordering the 24 x 7 FARS kit from scaled instruments.

Question:

Do I need this fan deflector part if I am using AC fan?
https://www.scaledinstruments.com/shop/davis-instruments/parts/vantage-pro2-parts/radiation-shield-parts/davis-7342-508-vantage-pro2-24-hr-spars-insulating-sleeve/

Thanks guys

[fkapp]

Is foam weatherstripping recommended to seal up area around case fan if one is going to go ac fars fan route?

[CW2274]

Is foam weatherstripping recommended to seal up area around case fan if one is going to go ac fars fan route?

Personally, I use nothing. 60CFM pulls plenty without.

[fkapp]

Thanks for quick response.
How is the low battery glitch going?

[CW2274]

Thankfully the glitch hasn't been back since I went out to the ISS and pulled the battery to check it and the solar panel. Just one of those "things" I guess...

[fkapp]

Good news!

Are these critical parts for the 24x7 FARS?
Davis 7342.508 – Vantage Pro2 24-Hr SPARS insulating Sleeve
Davis 7353.065 – 24-Hour SPARS Temperature Humidity Sensor Mounting Plate

Seems like they are for extra insulation, but with good airflow not sure how much really need them.

Thanks
Frank

[CW2274]

The plate is what the sensors is mounted to and slides into the groove of the sleeve to secure it. Whether you need this stuff, no idea since I'm not sure exactly what you're trying to do. Almost sounds like you should buy the 24hr shield only and be done with it. That is IF you plan on it having a fan. The 24hr shield is not designed to be passive.

[fkapp]

Thanks. Currently have dfars and want to convert it to 24x7.
The conversion guide on scaled instruments site doesn't list the core or insulator or this mounting plate.
Was curious as debating getting these too or just mod dfars to have fan run all time

[CW2274]

I don't believe DFARS will even accept the solid core, hence why it's not offered.

[fkapp]

Yeap. Need to buy 4 of the plates with drop holes
From reviewing the exploded view

[fkapp]

Update here that I went in with the 24 x 7 ac fan mod.
Building tonight installing tomorrow.
Sharing and want to say thanks to everyone for all the input and sharing their experience with this mod.

Curious if you guys use the screen at bottom of core or leave off?

Thanks and looking fwd to this upgrade
Frank

[CW2274]

Looks great! Leave the screen on, no need sucking up bugs ect. gumming up the sensor chamber and fan blades more than necessary.

[fkapp]

Makes sense. Will send update when up

Thanks
Frank

[Bashy]

Hey guys, would 46cfm be too high/low? I would buy that fan from near the beginning of the thread but with Amazon adding VAT it comes out at stupid money, I have however found an IP68 jobby on AliExpress and i will take my chances with VAT when it arrives, its cheap enough so they might let it go through, normally do.

I normally use standard PC case fans, chop off the corners and job done but they tend to only last a year before that start making noise, i normally swap them out when that starts and its normal when the temps hit <10C and only gets louder the cooler it gets. This year i didn't change it dure to back issues so for now i have added a smart plug to shut it down when the temps are sub 7C, crude but its works well.

So i am really looking at one for next year but if the fan finally fails, i want the new fan at hand so I can readily swap it out, so if the one above is ok, I will get it, thanks

[fkapp]

I think depends on climate in. Here in Buffalo the one I went with is 24 cfm.  Unless in hot climate don't think need more than 40 cfm but will lets see what guys that have been running ac fans longer say.

[fkapp]

Up an running and mod went smooth. Thanks again everyone for help.

Note: this is not main anemometer ( that is up on roof), have this one cause had iss slot avail and use to compare backyard level winds near garden for et etc.
Uv and solar face south

[azchrisf]

You may notice the temperature change quickly, because more airflow is going thru the sensor now. If it's too much, you could wire something in that drops the voltage to the fan. In Winter here, in my little science project I have linked below, it switches the fan from full voltage to 1/2 of it thru a 6V voltage regulator so it drops down to 1600rpm at night when it's cold, otherwise the temperature changes too rapidly for my liking.

[fkapp]

Hi,
Thanks for the tip.
Wonder if that is what is happening this evening see attachment below with temp falling fast and mesowest noting suspect data.

The fan I am using is:
https://www.coolerguys.com/products/mechatronics-80-x-25mm-ac-115v-fan-uf80b12-bth?variant=17667344517&utm_source=google&utm_medium=cpc&adpos=&scid=scplpshopify_US_5592657477_17667344517&sc_intid=shopify_US_5592657477_17667344517&gclid=Cj0KCQiAsqOMBhDFARIsAFBTN3evlYKb6T01AwGYcrJWRAN6le2buz36OOpGo61fPUW-InCDPPjUz9gaAoTYEALw_wcB

That is a pretty sophisicated setup you have there. I am not an electronics expert so not sure can pull that setup off.

Would something like this work?
https://www.amazon.com/Electronic-Controller-Variable-Adjuster-Hydroponics/dp/B07T9BLJ7L/ref=sr_1_5?keywords=Fan+Speed+Control&qid=1636418882&sr=8-5

I know there is a plug with controller inline from the fan manufacturer, but that presents 2 issues (one aesthetics, and 2nd will be extra place need weather proof box)

Would be nice to have something can control from inside when is freezing out, if have any tips on guides/ ideas on more automated/control from not going out to station to change dial would help. like your setup so hope a simpler version is possible so can give it a shot.
Thanks
Frank

[CW2274]

Wonder if that is what is happening this evening see attachment below with temp falling fast and mesowest noting suspect data.

You were flagged briefly for the dew point. The abrupt spiking does look curious.

https://mesowest.utah.edu/cgi-bin/droman/regress_database_top.cgi?stn=F6381

[fkapp]

Thanks for why and now know where to look if happens again.

Was clear and calm here so wonder if nearby stations being colder caused, or maybe too many cfm in my shield.

Will see if happens again.  Hope not as then may need to figure out how to throttle back 24cfm

[CW2274]

Will see if happens again.  Hope not as then may need to figure out how to throttle back 24cfm

I run my 60CFM 24/7 without dialing back anything and never see your problem. It ain't that.