| 摘要 |
PROBLEM TO BE SOLVED: To avoid lowering of thermal efficiency and intricate control attributed to air supply not only to the combustion plane under combustion but to the combustion plane under stoppage through rotation of a combustion fan under partial combustion state. SOLUTION: When a burner 2 has combustion planes A, B and C, the combustion planes B and C which can take combustion stop state individually and selectively during combustion of burner are provided, on the supply air inlet side thereof, with supply air passage open/close means 22b, 22c, respectively. Open/close operation of the supply air passage open/close means 22b, 22c is controlled at an open/close control section 24. The open/close control section 24 controls to open the means 22b during combustion of the combustion plane B and to open the means 22c during combustion of the combustion plane C thus supplying air only to the combustion plane under combustion through rotation of a combustion fan 6.
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