Abstract: A collective air intake and exhaust chimney suitable for outdoor installation which avoids clogging by snow or frost, which comprises an inner flue (8), a heat insulating layer (12), an outer flue (13), an intake passage (10) between the outer flue and the heat insulating layer, and an exhaust passage inside the inner flue. The device has a double flue branch (3) suitable for connection, e.g., to each floor of a building, which is preferably similar in size and structure to the double flue (8, 12, 13) of the intake and exhaust chimney, and is adapted to be slidably fitted to the intake and exhaust pipe of a forced draft direct vent type heater, and is supported by a supporting member.