Tjernlund SideShot SS2 SideWall Vent System for 4" Flue Pipe Includes the UC1 Universal Control. For Oil and Gas Heating Equipment. 70,000 - 168,000 BTU for Oil, 40,000 - 150,000 BTU for Fan Assisted Natural and LP Gas and 40,000 - 125,000 BTU Atmospheric Natural and LP Gas.