Bi-loop heat recovery system

In a furnace located in an enclosure, the furnace having a burner, at least one combustion air inlet formed in the furnace for permitting air to flow from the enclosure into the furnace for combustion, a draft diverter port formed in the furnace, an exhaust duct, and a stack coupled to the exhaust duct for exhausting the products of combustion from the enclosure, an improved system comprising:

• (a) heat exchange means which can be quickly and easily coupled to the exhaust duct to provide a first zone to carry products of combustion and a second zone in heat flow communication with the first zone to carry a stream of air;
• (b) first conduit means which can be quickly and easily coupled to provide gas flow communication between a point outside the enclosure and the second zone of said heat exchange means;
• and
• (c) second conduit means which can be quickly and easily coupled to provide continuous and uninterrupted gas flow communication between the second zone of said heat exchange means and the at least one inlet formed in the furnace whereby air for combustion in the furnace is supplied from a point outside the enclosure, and the air for combustion is preheated in said heat exchange means;
• wherein said second conduit means includes a first conduit coupled in flow communication between the second zone of said heat exchange means and said draft diverter port and further includes a second conduit coupled in flow communication between the second zone of said heat exchange means and said combustion air inlet.