4. Apply a ¼" wide bead of high temperature silicone all around at the 5" x 4" boiler reducer and wall termination connection. Slide adaptors on reducer and wall termination pipe all the way. Tighten with clamps. 5. Support the flexible vent pipe at regular intervals with brackets or hangers. Maintain arise per foot on horizontal runs. Avoid any sag in the vent. Do not bend pipe excessively. NOTE: Wrap 3" ceramic insulation around adaptor near termination and secure with sheet metal or foil tape and hose clamps to maintain 1" clearance. Installation of Galvanized Vent Pipe.