... Over-heating protection; 3.Over-water-pressure protection 4.Summer/Winter Gas water heater, tankless water heater1. Flame Failure Protection; ... Over-heating protection; Over-water-pressure protection2 Anti-water freeze protection ... lead or tin.Internal construction 6L,7L,8L,10L,12L,14L,16L,18L,20L flue type tankless water heater