... Protection; 2.Over-heating protection; 3.Over-water-pressure protection 4.Summer/Winter Gas water heater, tankless water heater1. Flame Failure Protection; Over-heating ... Summer/Winter selection; Very easy installation7. Heat efficiency >90%. Flue type gas water heater8. With shower. With One A5 size Instruction manual, injector ... 6L,7L,8L,10L,12L,14L,16L,18L,20L flue type tankless water heater