Heating Method Hot Water AHRI Net BtuH 51 000 BtuH Heating Capacity Input 70 000 BtuH Heating Capacity Output 59 000 BtuH Annual Fuel Utilization Efficiency 84 Percent Boiler Type Atmospheric Vent Hot Water Boiler Vent Diameter 4 in Return Connection Size 1 1/4 in Free Air CFM @ 10 Vacuum 1 1/4 in Series Aruba 5 Overall Height 39 1/2 in Overall Width 12 7/8 in Overall Depth 31 1/2 in Compatible with Product Type Home Heating Systems Manufacturers Warranty Length 1 yr Limited