- Tank-within-a-tank design - corrugated stainless steel inner tank; steel outer tank

- Negligible stand-by loss - less than 1/2°F per hourZone control description: Controllers for Circulator and Zone Valve Systems

- More Hot Water - Weil-McLain indirect-fired heaters produce twice the peak flow of a tankless coil; at least 50% more than a comparably sized direct-fired gas water heater; three times as much as an electric uni

- Unique self-cleaning design resists liming