Heating Method Hot Water, Domestic Tankless Coil Included No, AHRI Net BtuH 158,000 BtuH, Heating Capacity Output 182,000 BtuH, Annual Fuel Utilization Efficiency 86 Percent, Boiler Type Water Boiler, Return Connection Size 1 1/2 in, Free Air CFM @ 10 Vacuum 1 1/2 in, Series ...Heating Method Hot Water, Domestic Tankless Coil Included No, AHRI Net BtuH 158,000 BtuH, Heating Capacity Output 182,000 BtuH, Annual Fuel Utilization Efficiency 86 Percent, Boiler Type Water Boiler, Return Connection Size 1 1/2 in, Free Air CFM @ 10 Vacuum 1 1/2 in, Series Tobago (TWB), Overall Height 31 5/8 in, Overall Width 22 3/8 in, Overall Depth 24 5/8 in, Fuel Type Oil, Housing Material Cast Iron (Heat Exchanger), Standards AHRI Certified, ASME Certified, Vent Type Chimney