Oversizing the enclosure helps.. And Chuck tests were before current global warming effects. bazinga .... On Sep 17, 2015 8:12 AM, "Adam Moffett" <[email protected]> wrote:
> > What heat load was inside the box during these tests? I can believe all > this if the sun is the only heat source, but white paint won't evacuate hot > air that you're creating inside the box. > > On 9/17/2015 10:07 AM, Chuck McCown wrote: > > 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 <[email protected]> > *Sent:* Wednesday, September 16, 2015 5:13 PM > *To:* [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]> 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] >> > 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 >>> >>> www.Broadband-Mapping.com >>> >>> >>> >>> *From:* Af [mailto:[email protected]] *On Behalf Of *Sam Lambie >>> *Sent:* Wednesday, September 16, 2015 12:48 PM >>> *To:* [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 Office >>> www.Taosnet.com <http://www.newmex.com> >>> >> >> > > > > -- > -- > *Sam Lambie* > Taosnet Wireless Tech. > 575-758-7598 Office > www.Taosnet.com <http://www.newmex.com> > > >
