Draft Inducer Application Boilers Furnaces Water Heaters For Fuel Type Natural Gas Oil For Appliance Type Oil or Gas-Fired Furnaces Water Heaters Boilers Maximum Vent Pipe Diameter 12 in Minimum Vent Pipe Diameter 8 in For Pipe Slot Height 5 1/2 in For Pipe Slot Width 12 7/8 in Maximum Heater BTU Input for Gas Appliance 835 000 BtuH Maximum Heater BTU Input for Oil Appliance 1 030 000 BtuH Inlet Diameter 8 in Outlet Diameter 8 in For Vent Pipe Diameter 12 in