Abstract: A side wall termination unit for a gas boiler which terminates side by side vent and air supply pipes extending through a building side wall. The pipes extend through inside and outside plates on the internal and external wall surfaces. A one piece termination cap is mounted on the outside plate and includes a sleeve which holds the vent pipe in alignment with a vent opening in the cap. The intake end of the air supply pipe is butted against stops to keep it exposed. Extending around the sleeve and stops is a wall formed by spaced apart fingers which present between them air intake openings for allowing outside air to enter the intake pipe. A peripheral flange on the termination cap is spaced outwardly from the building wall to provide an air intake slot.