What starts the burner motor on an oil burner when there is a call for heat from the thermostat

• A. Thermostat
• B. Primary control
• C. Fan relay
• D. Oil pump switch

Answer: (B)

When the thermostat calls for heat, the signal goes to the primary control, which acts as the burner’s sequencing brain. The thermostat itself doesn’t power the burner motor directly; it simply completes a circuit that energizes the primary control. The primary control then starts the burner motor, starts the oil pump, and begins the ignition sequence, while also monitoring safeties. The blower or fan relay handles the air blower later in the sequence, and the oil pump switch serves as a safety interlock rather than the motor’s initiator.