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. 4.5% o2, 40 ppm, 82.6% efficient System is operating properly. Valved and drained the system. Replaced the Hi-vent on top of the air scoop and replaced the circulator gasket w/ bolts on the first floor circulator. Filled and tested the system.