Deciding if I should build this solar heater

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Warpspeed Guru Joined: 09/08/2007 Location: Australia Posts: 4406	Posted: 06:28am 11 Apr 2021         Quote   That last sentence worries me a bit Tony. Silver solder melts around 700 deg C and you do that on a pipe that has gaseous propane (highly flammable) inside?? Does propane behave like water and generates steam pressure at that temperature? Its only flammable in the presence of oxygen. If its 100% propane it can never burn. All that happens will be that the pressure increases with the temperature increase, and if you solder quickly with an oxy acetylene torch, soldering takes only a few seconds right at the crimped end. Water certainly works, but you need a good vacuum pump. Depends what you have I suppose.