A water heater heats water with a combustion gas. An exhaust tube includes one end portion and the other end portion, is connected to the water heater at one end portion, and inside thereof is defined as an emission path for the combustion gas. An exhaust pipe is greater in outer diameter than the exhaust tube, and a part of the exhaust tube on a side of the other end portion is introduced in the inside thereof. An exhaust terminal is attached to an end portion of the exhaust pipe and has an exhaust port for exhausting the combustion gas to the outside. An exhaust straightening member is attached to the other end portion of the exhaust tube and has an opening portion for allowing the combustion gas to flow out toward the exhaust port.