The hot oil boiler with a capacity of 1,500,000 kcal/h, which was established for the high heat requirement of the factory producing sound insulation and interior ceiling covering parts for the automotive industry in Gebze TOSB OSB, was successfully put into operation. The boiler system, which has an O2 trim and electronic proportional combustion system, is controlled by a PLC system. With the economies placed at the chimney outlet, the boiler efficiency has exceeded 92%.