9013.3 - Condensing ventoption: CATEGORY II:Vertical vent with combustionair from equipment roomThe flue outlet terminates on the rooftop.The termination point for the flue products mustfollow the vertical vent termination clearancerequirements on section 12.12. These units canbe identified by the CATEGORY II as noted onthe unit’s rating plate.The flue from this category II appliance musthave all vent joints and seams sealed gastight.A category II vent system has specific ventmaterial and installation requirements.The flue products in the vent system maybe cooled below their dew point and formcondensate in the flue. The materials used fora category II vent must be resistant to anycorrosive damage from flue gas condensate.Follow all requirements in section 5.1, 12.2and 12.9. Follow all requirements for ventingflue products to the outdoors with a verticaltermination as per section 12.12.Vertical direct vent installationwith rooftop combustion airinletThe vertical direct vent system is installed witha Category II flue and a separate combustionair pipe to the outdoors. The flue outlet andcombustion air intake must both terminate onthe rooftop.The termination point for the flue products mustfollow the vertical vent termination clearancerequirements on section 12.12. These units canbe identified by the Category II as noted on theunit’s rating plate.Follow all requirements in sections 5.1, 12.2and 12.9. Follow all requirements for ventingflue products to the outdoors with a verticaltermination as per section 12.12.The vertical direct vent system requires theinstallation of an additional pipe to supplycombustion air from outdoors directly to theappliance. Follow all requirements under thecombustion air inlet section 12.5.13 - INSTALLATION - CATEGORY II: Vent and combustion airFigure 13-2 Vertical vent with combustion airfrom equipment roomFigure 13-3 Vertical direct vent installation withrooftop combustion air inletEQUIPMENTROOMAIR OPENINGAIR OPENINGEQUIPMENTROOM
