PURPOSE: To provide an inhale and exhale duct for a forced inhale and exhale type burner used indoors, which duct is not influenced by outdoor wind and is easily installed.

CONSTITUTION: To a parting wall 2 that partitions the outdoor and indoor sections is provided a double wall type inhale and exhale pipe 1 in such a manner that it inclines downward to the outdoors. The double wall pipe 1 consists of an outer pipe 7 both of whose ends are closed by end plates 8, 9 and an inner pipe 10 attached concentrically with the outer pipe 7 whose indoor end is attached to an end plate 9 and whose outdoor end is attached to the inner circumferential wall of the outer pipe, the inner pipe acting as an exhale passage and the annular passage between the outer and inner pipes acting as an inhale passage. In this arrangement, the rain drops from outdoors and water condensed from steam in the exhaust will be discharged outdoors at all times, so that intrusion of water into the burner 3 can be prevented and the influence of the outdoor wind will be minimized.