Bob arrives at the job and meets the homeowner. She explains to Bob that the furnace operated all night and stopped running in the early morning. She leads Bob to the basement where the furnace is located.
Bob checks the thermostat wires and sees that the thermostat is calling for heat, but the furnace is cold. He removes the cover to the burner section of the furnace and discovers that the burner section has a lot of soot where one of the burners is inserted into the heat exchanger. The burners are ribbon-type burners (Figure 1). The flame roll out protection control had tripped and had to be reset (Figure 2). When the burner starts up, the flame on that burner is yellow and rolling out the front of the burner hole in the heat exchanger. Bob tells the owner that the burners would have to be removed and the furnace cleaned before start-up.