18″ Length Round Rigid Pipe (11″ Outer Diameter)
To calculate installed length, subtract 1 1/2″ (for 10″-16″ diameter) and 1 1/8″ (for 18″-30″ diameter) from each connection of vent. A 1″ clearance (air space) to combustible materials must be maintained. 18″-30″ diameters are built to order and are not returnable. For use with B-Vent Appliances only.