I have used one a fair amount...
and they work quite well. made of stainless & copper coils.I use the zodi for hot showers after scuba diving in the winter (in the Northwest, brrrr) But there are a few drawbacks. make your own conclusion...1) The water pressure at the sprinkler head (similar to the sunshower) is too low. I put a piece of tape over some of the holes & it sprays better.2) the water doesn't get hot enough. I recirculated the water in a 2 gal container for about two minutes until it got "hot" say, just enough to bare putting your hands in. I got just "warm" water when I used straight cold.good luck!