One summer about 15 years ago I set up an array of hoffman boxes
on tables out in the sun. I had them all rigged with telemetry
so I could log temps. I tried fans, peltier coolers, heat
exchangers, sun shields, insulation, thermally activated vents
and various colors. (That silver paint that the railroad uses is
lousy.)
Overall, the most dramatic lowering of temps was painting the box
a bright white.
There is a color called satellite white that was the best.
Biege/tan was not much better than the silver.
Then came sun shades and vent fans. About a tossup between those
two. But either one on their own was about half as effective as
the bright white paint.
Thermally activated vents are pretty nice if you don’t want to
use the juice to run a fan. They have either an aneroid
barometer type of cell full of ethanol or a piston full of
paraffin. Both expand when heated. They drive the louvers.
You can make your own piston if you can get the low temp
paraffin. Granger sells the louvers all ready to install.
Active cooling was dead last. Even with an insulated enclosure.
Was hard for it to remove any live load heating at all. Heat
exchanger was not much better.
*From:* Sam Lambie <mailto:[email protected]>
*Sent:* Wednesday, September 16, 2015 5:13 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] Cooling an outdoor NEMA box?
Thanks for the tips guys.
Site is rebuilt now. Now to add exhaust fans. I like the idea of
putting a heat shield in front of the door. I might just go with
that! Passive means nothing fails.
On Wed, Sep 16, 2015 at 4:53 PM, Jason McKemie
<[email protected]
<mailto:[email protected]>> wrote:
The "roof" of the fan cooled DDB boxes that I've gotten
essentially do this, with fans mounted on the inside of the
enclosure at the top venting outwards (under the solar
shield) - seems to be fairly effective.
On Wed, Sep 16, 2015 at 12:26 PM, Brian Webster
<[email protected] <mailto:[email protected]>>
wrote:
Don’t discount the idea of installing a flat plate on the
sun facing face with standoffs. Just having that absorb
the sun and heat with the air gap beneath does a lot
towards not letting the heat build up inside the box.
While there will be some conduction it will be a lot less
than the direct radiation from the sun.
Thank You,
Brian Webster
www.wirelessmapping.com <http://www.wirelessmapping.com>
www.Broadband-Mapping.com <http://www.Broadband-Mapping.com>
*From:*Af [mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of *Sam Lambie
*Sent:* Wednesday, September 16, 2015 12:48 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* [AFMUG] Cooling an outdoor NEMA box?
I am in the process of rebuilding one of our sites from
an old wooden box to a more robust NEMA Wall mount
cabinet that is 36x36x12.
Unfortunately, the cabinet is on the southern side of the
building and I am wondering how to cool the damn thing
during the summertime heat.
I would like to install a 4 inch 100vac fan to suck air
out with an intake port on the other side. But it would
be nice if the fans could be temperture controlled. Has
anyone done this? And what have you used to make it happen?
Sam
--
--
*Sam Lambie*
Taosnet Wireless Tech.
575-758-7598 <tel:575-758-7598> Office
www.Taosnet.com <http://www.Taosnet.com>
--
--
*Sam Lambie*
Taosnet Wireless Tech.
575-758-7598 <tel:575-758-7598> Office
www.Taosnet.com <http://www.newmex.com>
