Rocket Water Heater v.2

Not sure if proper protocol is to make a new thread or to continue the original and edit the title. If I am doing it wrong, please let me know.

The original thread concept was around a constructing a boiler for use in a home heating/water heating setup. After the excellent feedback in the thread I have since shifted to working on an open air "water heater" design to replace the pressurized boiler.

Sketch one is my initial idea for the heat exchanger. The egg shape, big endian up, is from recommendations of Viktor Shauberger on how to most efficiently heat water. Vanes will be bent and welded to the egg exterior to encourage the flames spiraling around. Still unsure if the egg will be copper or iron. Copper would be best but sooo expensive rn. Probs just use iron but we will see what mysteries the scrap yard holds...

Second sketch is system layout again. This time with the addition of an insulated temporary hot water tank that can be pumped from back into the "battery" the water came from on insulated lines.