Soldering Copper and Stainless Steel

[voipio]

Impressed. What grade of stainless was it, out of interest, and did the solder definitely flow down the gap between parts? Looking at the images, the heat exchanger ports are brazed, or silver soldered on, so trying to braze could have ended in tears.

 

[awemawson]

I don't know the stainless grade - it's construction is stainless plates copper brazed - the solder wetted the stainless beautifully (copious Zinc Chloride flux before assembly and during soldering and was sucked down the gap between the 54 mm copper fitting and the stainless female collar. For the 28 mm pipe to be a nice fit in the adaptor I had to lap it down a bit in the lathe using emery cloth as it was too tight - need somewhere for the solder to go! I suspect that it is actually 1" pipe - I've had it for 'some while' !