JJLL wrote:Also, solder melts at roughly 300 °F. Water boils at 212°F In short, your pressure relief valves would blow before the soldering failed.
The solder won't fail if the tube is full of water. I run 375* steam through soldered joints and they don't fail. It melts at 300* the first time, it takes more to remelt it. I'm not sure how much more.
I would not recommend copper for a coil however.