Patent ID: 7137360

Claim:
A boiler comprising: a) a housing with a flue gas inlet for allowing a flue gas flame to enter the boiler and an outlet for venting a flue gas produced by the flue gas flame; b) a tube assembly mounted within the housing, the tube assembly comprising: i) a lower manifold for receiving a liquid, ii) an upper manifold for receiving a heated version of the liquid; iii) a downcomer pipe connecting the lower and upper manifolds for providing natural convective circulation of the liquid when a burner fires into the boiler; iv) a plurality of tubes disposed between the lower and upper manifolds, wherein a majority of the plurality of tubes include lateral tube runs having a longitudinal extent oriented substantially perpendicular to the plane of the flue gas inlet and, the plurality of tubes being shaped to provide, in combination with adjacent tubes, a flue gas pathway oriented in a parallel fashion with respect to at least a portion of the length of the tube runs along the longitudinal extent of the majority of the plurality of tubes in the tube assembly to the outlet; and v) a plurality of blocking members generally oriented horizontally with respect to the longitudinal axis of the lateral tube runs and located on a portion of some of the lateral tube runs to restrict the vertical extent of the flue gas thereat, wherein, during use, the liquid introduced into the lower manifold travels in the plurality of tubes and receives heat from the flue gas flow along the extent of the flue gas pathway.