Author Topic: Davis VP2 Aspirated and Non-Aspirated Comparison  (Read 2239 times)

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Offline wxtech

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Davis VP2 Aspirated and Non-Aspirated Comparison
« on: June 13, 2009, 11:54:53 AM »
I have just started a rather crude comparison of fan aspirated vs non-aspirated.  I have a FARS solar shield.  Today I will control the fan from my inside weather station/workbench.  
At 11:35AM Eastern, I turned the fan on.  
At 11:45AM, I turned the fan off the temperature was then 81.7ºF
I will cycle the fan on/off at 15 minute intervals.  
At 12:00 I will turn the fan on again.  Watch the graph on my weather site for detectable differences with the fan on/off.
http://www.lexingtonwx.com

This is the starting graph @ 11:41AM
« Last Edit: June 13, 2009, 12:05:37 PM by wxtech »
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, VWS v15.00 p02. ImageSalsa, Win7 & Win8 all-in-one.

Offline wxtech

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Re: Davis VP2 Aspirated and Non-Aspirated Comparison
« Reply #1 on: June 13, 2009, 11:58:23 AM »
You can tell from my solar radiaton graph on the site that it's an overcast day with clouds causing the temperture to vary considerably.
This makes this real conditions test not a good comparison of the temperature conditions.
I will set up an automatic timer with the FARS inside on my workbench for a more controlled conditions test.
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, VWS v15.00 p02. ImageSalsa, Win7 & Win8 all-in-one.

Offline wxtech

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Re: Davis VP2 Aspirated and Non-Aspirated Comparison
« Reply #2 on: June 13, 2009, 12:43:13 PM »
2 hours of comparison:

11:30 fan on
11:45 fan off temp 81.7º
12:00 fan on temp 81.9º
12:15 fan off temp 83.2º
12:30 fan on temp 83.8º
12:45 fan off temp 84.0º
1:00 fan on temp 85.0º
1:15 fan off temp 83.2º
1:30 fan on temp 84.2º
I see no effect from the fan on/off.
Experiment stopped.  Fan will remain on.
« Last Edit: June 13, 2009, 01:44:47 PM by wxtech »
Al Washington, Lexington, Ga.,  NWS Coop station=LXTG1, Fischer Porter, SRG, MMTS. 
CoCoRaHS=GA-OG-1. CWOP=CW2074.  Davis VP2+ WLIP 5.9.2, VP(original) serial, VWS v15.00 p02. ImageSalsa, Win7 & Win8 all-in-one.

Offline dalecoy

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Re: Davis VP2 Aspirated and Non-Aspirated Comparison
« Reply #3 on: June 13, 2009, 12:56:16 PM »
Wouldn't you expect the effect to be very small on an overcast day (or overcast night)? 

i.e., it's a radiation shield.

Offline Aardvark

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Re: Davis VP2 Aspirated and Non-Aspirated Comparison
« Reply #4 on: July 02, 2009, 10:20:12 AM »
I find with my study at least a 2-9 degree difference depending on the sun's angle to the solar panel on my daytime unit .

IF..I had it to do over again...I would go with the 24 hr FARS, but I think as long as my unit is working or repairable... we stay put.