I Have the small Bosch Ng 117000 btu ,in winter my water gets to 33f. I
never have it on high in winter or the water is to hot for a hot water
shower. There are 180000 ++btu Ng -propane models they are good for 2
showers. Bosch, Takagi, Rinnai are all good. Id be sure to drain the
unit for freezing, instal valves in the proper area. My unit uses no AC
it has 2 D cells for piezo ignition. Tankless are worth it and ideal
for a cabin. Electric use to much power 120a for a small bosch.