| Alan,
A standard propane burner is all that is required.
Oxy/acet is just too harsh for silver soldering, it is ok for brazing with a carburising flame, but not for what you want.
Also remember that the flame should not go anywhere near the silver solder, heat up somewhere nearby and the solder will flow towards the heat. A good flux like Tenacity 4A will give you a good margin on heat range and ensure that you get good penetration.
When soldering in your bushes use either a graphite pencil or tipex (if you can find any) to draw a barrier line around the bushes, this will stop the silver solder from flooding over your boiler.
John |