Question: Hi there, I read your ideas on wrapping soft copper around the stove pipe to create hot water. Could you go into this in depth or tell of a book/article that does? What's the largest copper tubing you could use and could we transfer it to an old galvanize hot water tank that refused to warm water even though we put it in the sun??? Thanks! gw Answer: I have seen these ideas in older books, but I cannot recall where. I've never done the stovepipe one (although there were some commercial products that did it)...but I've put a few on the rear of stoves. We used 3/4 inch copper pipe, and found 180 elbows so a serpentine (back and forth) could be created. At one point we did even better. A local company that produced the finned copper coils for domestic hot water coils (located in the water jacket of hot water boilers) finned these sepentines for us. Since these were finned, they picked up heat much better than plain copper. We'd mount these on the outside of stove..on the rear, and sometimes mount a sheet metal shield behind them to trap the heat. If the tank is below the stoves, we'd add a control and small brass pump (1/50 to 1/100 hp) so that when the water heated up to 140 degrees, the pump would circulate it to the tank. In certain cases, if most of the tank was located above the coper coils, the water could circulate without a pump. Use the largest pipe size (3/4 is good) and have the pipe rise to the tank. The return pipe should come off the bottom of the tank and return to the bottom of the coil. If you look through some of the solar books, they might reference this type of setup as a backup... And DON'T forget a pressure relief valve located on top of the coil...with no valves between the coil and it.