Tanks and coils are all stainless steel construction;Large, smooth-wall coils deliver full output for years - no finned tubing to collect lime and sediment;Over 2" of insulation, providing less than 1 Degree / hr. heat loss;Flexible thermoplastic jacket that will not corrode and resists denting;All connections are on top on the standard units for a neat, quick, and clean installation;Brass drain and relief valves are factory installed;A high quality thermal well comes standard;Models are available in 30, 40, 50, 60, 80, and 115 gallon sizes;Bank together 80 and 115 gallon units for applications with high water heating demands;Limited warranty residential installation, 5 year commercial