Abstract: Draft inducers (50,40) having hollow axis (73a,73b), folding impellers (37a) or retractable propellers (37b) having limited presence in the flue path, external motor (47a, 47b) with sensors (33a, 33b), male connection (63a, 63b) and female connection (65a, 65b) ends for connecting with flue stack and other tandem modules.

Abstract: Auxiliary heat ejectors (380A, 490) having an optional independent circulator module (380D), heat exchange radiators (41e, 41f), heated fluid inlet lines (21e, 21f) and exchange fluid return lines (47e, 47f) with pumps (49e, 49f) connected to other tandem modules such as heat sources (30E, 40F) incorporated by reference, a flexible helical corrugated body (53e) or a retractable modular unite walls (53f) on cart wheels (25f), actuators (23e, 23f), partitions (35e, 37e, 37f), inlet and outlet end having flanges (45e, 45f, 35g) for connecting with shared ductwork of a primary heater. The independent circulator module (380D) comprises of a flexible body (41g), support (21g), flow check gate (31g), a blower motor (27g) with propeller 25g.