Question 168Motor Plants - 1st Asst/Chief

The correct answer is A) back to the suction side of the service pump. When lighting off a cold boiler equipped with a return flow fuel oil system, the recirculating valve directs the flow of oil back to the suction side of the service pump. This allows the oil to be recirculated and heated through the fuel oil heater before being directed to the burner. Directing the oil back to the suction side ensures the oil is properly warmed up and ready for combustion, rather than sending it directly to the fuel oil heater inlet, deep tanks, or fuel oil settler, which would not properly prepare the cold oil for the boiler. The other answer choices are incorrect because they do not properly describe the function of the recirculating valve in a return flow fuel oil system during boiler light-off.