High efficiency central heating boiler - uses spirally wound heat exchanger around combustion chamber and around coaxial insulation block

摘要

The fuel enters the combustion chamber (2) via a nozzle assembly (3)in which it is mixed with incoming air. The air is drawn by a fan (18) to the nozzle and burner through the outer casing of the boiler housing (1). The burning mixture heats a cylindrical grid (13), surrounded by a spirally-wound tube (5). A certain amount of the inlet air also enters the heat exchanger from the combination chamber (16) via openings (19) in the wall. The tube has small dia. fins (6) to assist the heat transfer. At the end of the combustion chamber is a body of heat-insulating material (10) surrounded by an extension of a tube (5') which has larger dia. fins (7). The heat transfer medium, e.g. water, is pumped through the spiral tube and the heated medium leaves the boiler via a pipe (8) at the other end. The outer air inlet casing is separated from the heat exchanger assembly by a cylindrical intermediate wall (11) of insulating material. The exhaust gases leave the boiler via a vertical flue (12) with a condensate drain (20).