Combustion apparatus

A combustion apparatus comprising a plurality of independently-controllable combustion areas, each comprising a single combustion burner or a plurality of combustion burners arranged in parallel, whereby the combustion capacity of said combustion apparatus is capable of being changed to any of a plurality of combustion capacity levels by selective combustion of at least one of said multiple combustion areas,

• wherein said combustion apparatus is configured in the form of a latent heat recovery type water heater equipped with a latent heat recovery heat exchanger for recovery of latent heat from combustion exhaust after flowing through a sensible heat recovery heat exchanger for sensible heat recover;
• wherein said combustion apparatus is provided with (a) an exhaust stack therethrough for passage of post-latent heat recovery combustion exhaust past said latent heat recovery heat exchanger, said exhaust stack being connected, by in-situ mounting, to an outer exhaust stack formed as a separate body from said exhaust stack and not composing said combustion apparatus, (b) a combustion exhaust temperature sensor for detecting the temperature of the post-latent heat recovery combustion exhaust past said latent heat recovery heat exchanger, disposed in said exhaust stack and (c) a control means for monitoring of the temperature of combustion exhaust detected by said combustion exhaust temperature sensor and for performing a safety process for preventing said outer exhaust stack from degradation in thermal durability if the detected combustion exhaust temperature exceeds a specific judgment temperature for high-temperature abnormality judgment;
• and
• wherein said control means is provided with range of judgment temperatures that are set so as to correspond respectively to multiple combustion capacity levels, whereby said safety process is performed based on the specific judgment temperature corresponding to a current combustion capacity level.