Chapter 4 Fuel Units and Oil Valves Figure: 4-23: Delayed oil valve installation for interrupted ignition Chapter 4—Fuel Units and Oil Valves 4-19 Primary Control Burner Motor Delayed Oil Valve Ignition Trans. Do Not Connect Delayed Oil Valve To This Line valve opens and oil is supplied to the nozzle. On burner shutdown, the delayed oil valve closes immediately, shutting off the fuel supply and providing a clean cutoff of the flame. Without the delayed oil valve, the motor speed must decrease before the pressure regulating valve closes, which again causes smoke because of a lack of air. Note: The delayed oil valve will only produce a clean shutdown if the oil supply system is free of entrapped air. The delayed oil valve will not control nozzle after drip that results from air in the oil supply system between the valve and the oil nozzle. This air is caused by an air leak in the suction line or pump fittings or high vacuum. Installation: The delayed oil valve is installed on the output side of the fuel unit. Standard 1/8" (I.D.) black iron pipe can be used to connect the inlet port of the delayed oil valve to the nozzle discharge port on the fuel pump. Use of the 1/8" pipe provides a rigid mounting for the valve. The coil is electrically connected in parallel with the burner motor. See Figure 4-23 for a wiring diagram. If the burner has interrupted ignition, be sure that the solenoid valve is connected to the motor leads and not to the ignition leads. If the valve is inadvertently wired to the interrupted ignition circuit, the valve will close when ignition is cut off and burner will go off on safety lockout. It is code in most jurisdictions, and good practice in all cases, to run the electrical leads from the delayed oil valve through Greenfield tubing to protect electrical leads from the valve to the burner junction box. The oil valve housing cover is threaded to accept Greenfield connectors or the tubing itself. Use anti-short bushings on the ends of the Greenfield. A handy device to have for the installation is a double Greenfield (BX) connector that allows two pieces of Greenfield to be connected to a single hole. This will make the electrical installation much easier in cases where the burner junction box does not have an extra outlet hole.
NORA Oilheat Technicians Manual
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