NTI Boilers Watertube Boiler 94% AFUE 5.3:1 Turndown, 400k-Input, 375k-Gross Output, 225 lbs, Water Content-2.4 gallons, 1-1/4" FPT Heating Connections, 3/4" FPT Gas Connection, 4" Vent Size, Dimensions-24-1/2"D x17-1/2"W x36-3/8"H