Central heating boiler unit - heats water above combustion chamber and in downward flue duct which has draught fan started before lighting burner

摘要

The oil fired unit comprises a boiler (1) with burner (3) in the combustion chamber (2) and a first heat exchanger (4) to heat the circulating water with a flue gas chamber (5) above it. The chamber (5) connects to a downward duct (8) by the side (10) of the boiler, which contains a second heat exchanger (9) and leads to the chimney (6). The duct (8) is thermally insulated from the side (10) and has a condensate trap (30). The exchanger (9) is made of smooth tube and is higher than exchanger (4). The flue ducting contains draught fan (7) which is started before lighting the burner and stopped after switching the burner off.