4.0 MM BTU/Hr Therminol Oil heater. Manufactured by Struthers Wells, Model 5CV12.5-4. Built 1972, blower upgraded 1997. Natural gas fired. Flow Configuration: Single flow path, serpentine coil. 280 square foot radiant section, 405 square foot convection section. Designed for 150 PSI @ 700 deg. F. Specs on File.