5-277-06-066-001

Built around a double-wall two-pass U-bend bundle, this configuration delivers in-tank heating with boiler water in the tubes and cross-contamination protection for demanding service. The vented air gap between tube walls gives a visible telltale leak rather than allowing boiler water and tank contents to mix. Physically, the unit runs a 6-inch shell in a 2-pass arrangement. It carries 3/4-inch O.D. tubes. That combination is cataloged as 5-277-06-066-001. The build specifies cast iron bonnets, steel shell, and copper (double wall) tubes. The unit is rated for 150 PSI on the shell side, 150 PSI on the tube side, and 375°F maximum temperature. The series sees regular use in institutional and health care water storage, potable water storage tanks, and domestic water storage under double-wall codes.