Originally Posted by Solar Mike
Heat pipes would work very well clamped or soldered to the fins of a flat panel collector, I have been doing quite a lot of experimenting building heat pipes of various sorts over the past 6 months for extracting waste heat from gray water (shower drain).
A 2.4m heat pipe soldered to a copper fin 160mm wide would be extremely efficient at conducting the heat collected by the fin to the condensing end of the pipe, pipe dia would be only have to be 8 - 10mm, evacuated to 50 microns and using approx 1cc of water inside the tube. To do this the water is placed in the tube, frozen, then evacuated. This setup would be immune from frost but with a lot of added complexity, just to save a bit of copper with water flowing through it and you require specialist vacuum pump to get the pressure low enough to use water. I have used R22 refrigerant gas quite successfully in heat pipes when extracting heat from lower temperature surfaces.
Do you use silver solder on those pipes?
What are the steps for make the R22 heat pipe?
I'm wondering if an R22 (lower temp extractor) heat pipe could be used
to fabricate a compact water-to-water heat scavenger to recover the
heat in waste
Shower water.?. Luke warm water..
A smaller exchanger might be just the thing for my shower..