Eccotemp L5 Propane Water Heater 

Winter 2024 update - after a week of temperatures well below freezing, even getting near zero F, the unit could not empty fully before freezing again and a small crack was created in one of the upper tubes, fortunately at an accessible spot. I repaired it with Alumiweld and it's back in service. One consideration is to try blowing the unit out with pressurized air to reduce the chances of a bit of water remaining causing a crack.