| 摘要 |
PROBLEM TO BE SOLVED: To prevent combustion failure when a plurality of combustion devices connected by a collective exhaust cylinder are operated simultaneously.SOLUTION: Respective revolution speeds of combustion fans 5a, 5b, 5c of combustion devices 2a, 2b, 2c are detected. When the combustion fan of at least one of the combustion devices continuously has the revolution speed lower by predetermined determination revolution speed or more, than those of the combustion fans of the other combustion devices, the number of burners having fire in the combustion device having the combustion fan revolving in low revolution speed is reduced so that combustion operation is performed in a low stage combustion rate range in the low combustion rate stage being low by one stage. |
