Abstract: A more efficient heat exchanger with walls of heat exchanger coils oriented at compound angles with respect to its associated heat exchanger fan. The bottom edge of each heat exchanger coil wall is oriented at an angle of between approximately 35 and 85 degrees to the fan, and each heat exchanger coil is tilted inward at an angle of between approximately 35 and 85 degrees relative to a plane connecting the two bottom edges of the heat exchanger coil wall. One or multiple coils can be provided in each heat exchanger coil wall and an optional top heat exchanger coil can be added to the top of the heat exchanger. The front of the heat exchanger, which is normally pointed for forced draft units, is replaced with a triangular shaped plate and a modified trapezoidal shaped base for induced draft units.

Abstract: A flow assembly has a hollow housing including a lumen extending from a proximal aperture to a distal aperture. The flow assembly can have a first set of blades including at least one first blade disposed within the lumen, wherein the at least one first blade extends from the housing and can be positioned between the proximal aperture and the distal aperture. The flow assembly also has a second set of blades including at least one second blade disposed within the lumen, wherein the at least one second blade extends from the housing and can be positioned between the at least one first blade and the distal aperture. Also, the flow assembly can have a central passageway substantially free of blades extending from the proximal aperture to the distal aperture.