Mandrel benders are cheap most places and will do the same thing better... Darryl McMahon wrote:
>Ken wrote: > > > >>Hi all, >> >>Sorry for the long subject line but, I thought it may aid in archive >>searches... Is there a home remedy to creating a double wall heat exchange? >>I have contemplated buying two sizes of copper tubing, inserting the smaller >>inside the larger and bending the two simultaneously. I could see how the >>inner tubing might kink or flatten out but, I think that would be unlikely >>unless I tried to bend too tight of a radius. Is there a better home-builder >>solution? Perhaps there is an affordable storage tank commercially available >>that makes building a backyard heat exchange mute anyway.? I'm going to need >>to come up with a storage tank anyway. I understand the theoretical >>pros/cons to internal and external heat exchanges but, what are the >>real-world practical differences? >> >> >> > >Disclaimer - I have not tried this myself. >I have read (somewhere) that if you start with straight tubing, then pack sand >between the two tubes before making your bends, this will avoid/ reduce >kinking in >the inner tube. Of course, the trick is probably getting all the sand out >again >before plumbing this new arrangement into the lines. > >If I end up going this route (double-wall) some day in the future, I think I >will >put two coils into an exchange tank instead. One coil provides the heat input >from >the solar collectors, the other coil provides the heat input to the >conventional >hot water tank. The tank will have a sealable lid, and a lot of insulation. >Both >coils will be immersed in water in the tank. This way, the lid can be removed >for >inspections, and the coils can be removed fairly easily for repairs. > >To date, my solar water pre-heaters are in-line, so no heat exhangers required. > >Darryl McMahon > > _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
