Patent ID: 7647897

Claim:
A heating apparatus comprising: a burner, a combustion gas passage for guiding combustion gas generated in the burner, a primary heat exchanger for heating water by heat of the combustion gas and positioned in the combustion gas passage, and a secondary heat exchanger for heating water by heat of the combustion gas and positioned in the passage downstream of the primary heat exchanger, wherein the primary and secondary heat exchangers are connected so that water having passed through the secondary heat exchanger flows into the primary heat exchanger, wherein the secondary heat exchanger comprises a number of heat receiving tubes arranged in parallel, wherein the secondary heat exchanger comprises a pair of headers between which the heat receiving tubes are arranged in parallel, the headers each comprising a tube plate with a surface to which the heat receiving tubes are fixed and a passage-forming member positioned at another surface of the tube plate so as to form a part of a water passage, the headers functioning as parts of walls of the combustion gas passage extending from the burner to a gas-discharging portion.