[wxqc] Opinions please -- New design for solarradiation shielding

[Isaac Kishk (CW6261)]

I tried passive in texas, but the sun heated up the tube so much it
altered the readings more than it caused a natural chimney effect.  I
even tried a double tube .. where the outside 3" tube was black, the
inside 3" tube was white w/ the instruments inside the 2", same
problem (not as bad though).  In the end I went w/ a 12v fan running
around 8.5v off a battery and solar panel.
http://weather.gladstonefamily.net/site/C6261

(i need to relocate the panel so it kicks on earlier, as you can tell
by the graphs)

On 5/5/07, Bryce Alexander <bryce at azlab.net> wrote:
> I had seriously considered using something similar to yours, but I am trying
> to come up with something that is passive, even in Arizona, rather than run
> power to the fan for aspiration. What makes my design unique is that by
> placing it at an angle (similar to the angle of a solar panel) the
> convective nature of the air will self aspirate the tube. An inverted J
> design will trap warm air at the top and absolutely require fan aspiration.
> What makes this angled design unique is that it shouldn't require the fan.
>
> The fact that it is a tube is only a small part of the overall design.
>
> -----Original Message-----
> From: wxqc-bounces at lists.gladstonefamily.net
> [mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Philip
> Gladstone
> Sent: Saturday, May 05, 2007 7:45 AM
> To: Discussion of weather data quality issues
> Subject: Re: [wxqc] Opinions please -- New design for solarradiation
> shielding
>
> Thomas Giella KN4LF wrote:
> > Hi Bryce,
> >
> > I tried that design 20 years ago and it worked fairly well with forced
> > aspiration but shortwave radiation and precipitation entry was a problem
> at
> > certain times of the year. I ended up using a white plumbing PVC tee and a
>
> > couple of 45 degree elbows and that kept shortwave radiation and
> > precipitation out. For ventilation I used a DC 45 cfm computer type muffin
>
> > fan, with the fan sucking fresh air in from the front and passing across
> the
> > sensors before reaching the fan. This design worked as good as my louvered
>
> > Stevenson Screen.
> >
> > BTW the bottom of the shelter should be 4-5 feet above ground level.
> >
> >
> >
> I am now using a similar design -- an inverted J made out of PVC with a
> muffin fan. See the pictures on
> http://weather.gladstonefamily.net/site/C0003
>
> Philip
>
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