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NORA Oilheat Technicians Manual

Specific Microprocessor-Based Primary Controls The following section is intended strictly as an overview. While other manufacturers may have similar controls, these are the units that you are most likely to encounter. Also, remember that manufacturers periodically add improvements and additional features to their controls. It is critical to consult product specific literature to verify information regarding individual controls, even if they are familiar to you. Riello primary controls Riello primary controls are designed exclusively for use on Riello burners. The Riello primary control, in combination with the coil of the oil valve and a cad cell, monitors and controls all functions of the burner. An auxiliary tap on the motor windings provides a 46-volt AC power supply to operate the control. The oil valve provides the starting and running circuits for the primary control through a logic board and safety lockout switch. The ignition transformer is integrated into the primary control and provides interruptedduty ignition. There are no thermostat terminals on current Riello primary controls. An additional device, such as a switching relay, must be used for low voltage thermostat connections. The Riello control’s safety switch is equipped with a contact allowing remote sensing of burner safety lockout. Should burner lockout occur, 120 Volts AC is supplied to sub-base Terminal 4 to activate any connected remote alarm systems. Wiring • All wiring is connected through the control’s sub-base terminals. • A wiring diagram is supplied with each control and serves as an insulator on the underside of the control. This diagram should always be left in place to protect the printed circuit board of the control. • When working on these controls, most experienced Service Technicians refer to Riello’s plastic laminated troubleshooting card or the troubleshooting guide provided in the training manual. Operation If all components are functioning properly, the control is in standby mode until 120 volts is supplied through the limit control to Terminal 5. Then assuming that the cad cell does NOT sense light: • The control is energized and Terminal 6 is powered, providing 120 Volts AC to the motor. • The auxiliary winding tap provides 46 Volts AC to power the control. • The motor starts and establishes a 10- second “valve-delay-on.” • The oil valve opens, supplying oil to the nozzle line, and at the same time the ignition is powered. • Once the cad cell senses flame, the ignition circuit is opened and the spark shuts off. • As long as the cad cell senses flame, the oilburner continues to run until the demand for heat is satisfied. • If the control does not sense flame Chapter 11 Primary Controls 11-16 Primary Controls Chapter 11—Primary Controls 11-17


NORA Oilheat Technicians Manual
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