Arrived onsite for heating maintenance 2 gas fired furnace 1 in rach apartment attic. 43B System: Turn heat on and confirmed operation. Changed 16x25x1 filter provided by customer. Brushed and Wiped down furnance blower cabinet and gas burners. Burners fired and are in good working order. No visual impingement detected. Cleaned the flame sensor. Measure temperature rise at 30 degrees. System is operating as it should.
