Performed a heating pm on an oil boiler. Brushed and vacuumed. Replaced the oil filter, nozzle and strainer. Started and checked the safeties. Performed a combustion test. 6.4% o2, 20 ppm, 81.6% efficient System is operating properly. There is a lot of corrosion on the domestic coil and the boiler drain. Can not repair those items without replacing the boiler.