This practice represents the case where the boiler was of old low efficiency model, and sized to match the full load of the production line, which rarely occurs. Reviewing the load pattern of the production line, the boiler can be replaced with smaller models, increasing the load factor, and thus the boiler efficiecny. Having the new boilers connected in parallel also provides operational flexibility. another benefit from this upgrade is the fuel switching from the heavy fuel oil existing boiler to diesel fired boiler, which is more economic and have less environmental impact.