Abstract: An outdoor condensing furnace is provided with a condensate drain line which passes through the heat exchange compartment and to a location within the building where it can be discharged at temperatures above freezing. During heating operation, the drain line is maintained at temperatures above freezing such that the condensate will not freeze, and if condensate is trapped in the drain line and freezes during periods of nonheating operation, then it will be quickly thawed when heating operation is resumed. In an alternate embodiment, a drain pan is placed in direct contact with the primary heat exchanger and the condensate is routed to drain pan to be vaporized. Another embodiment provides for routing of the condensate from the condensing heat exchanger, through a flue pipe, and to a drain site which is at above freezing ambient conditions.

Abstract: An outdoor condensing furnace is provided with a condensate drain line which passes through the heat exchange compartment and to a location within the building where it can be discharged at temperatures above freezing. During heating operation, the drain line is maintained at temperatures above freezing such that the condensate will not freeze, and if condensate is trapped in the drain line and freezes during periods of nonheating operation, then it will be quickly thawed when heating operation is resumed. In an alternate embodiment, a drain pan is placed in direct contact with the primary heat exchanger and the condensate is routed to drain pan to be vaporized. Another embodiment provides for routing of the condensate from the condensing heat exchanger, through a flue pipe, and to a drain site which is at above freezing ambient conditions.