My wife and I use solar showers and garden sprayers for bathing, supplementing with hot water from the stove if necessary. We had an engine HW exchanger but it stopped working a couple years ago. We try not to run the engine that much anyway. We like the simplicity, but in colder climates it might be nice to have something a little more robust.

I just stumbled across this unit. No pilot flame, adjustable self-regulating temperature output. It's a bit pricy, but appears to be well made.

I'd be interested if anyone has experience with one (or something similar).

Thanks,
Max

http://www.precisiontemp.com/pt_rvmd_m500.html