Patent ID: 8528538

Claim:
A warm air furnace comprising: an air intaker which takes in outdoor air; a combustor which is supplied with air taken in by the air intaker together with combustion gas so as to combust the same; an exhauster which exhausts combustion gas combusted at the combustor outdoors; a thermal exchanger which is provided at the exhauster and which is for transmitting heat of the combustion gas combusted at the combustor to indoor air; an air blower which blows indoor air so as to have heat transmitted from the thermal exchanger; and a drain discharger which discharges drain formed from condensation of water vapor inside the combustion gas at the exhauster; wherein the drain discharger is a conduit with a first end connected to the exhauster and a second end portion opened into the warm air furnace below the exhauster, the second end portion of the drain discharger is formed into a tubular portion with a membrane generated at a plane orthogonal to an axis line of the tubular portion by a surface tension of the drain, a leading end of the tubular portion is formed as an opening having an area large enough such that the membrane is not generated by the surface tension of the drain, and the tubular portion is formed by caulking a side surface of the second end portion.