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NORA Oilheat Technicians Manual

can cause a vibration and put an extra strain on the motor bearings. Any fan wheel that does not slip off the motor shaft without needing to be pried off with a screwdriver must be removed with a wheel puller. When replacing the burner fan, one must pay strict attention to the rotation as indicated by the beveled blades. Also, remember that the burner manufacturer has provided the proper fan for the proper amount of combustion air needed. Always replace it with one that has the same dimensions. Fuel pump The fuel pump, also referred to as the fuel unit, is driven by the motor. The pump shaft is attached to the motor shaft by the burner coupling. The pump consists of three basic parts: 1. Strainer—to remove any foreign matter from the oil before it enters the pump gears. 2. Pump—to lift the oil from the tank and deliver it to the regulating valve. 3. Regulating valve—to build up and maintain the proper operating pressure for atomizing the oil. (See Chapter 4 for more details on Fuel Units.) Ignition transformer or solid state igniter The ignition transformer or solid-state igniter (on new burners) provides a “step up” from the line voltage of 120 volts to over 10,000 volts. The high voltage spark produced by these components jumps across the gap between the electrode tips. This spark provides the heat necessary to vaporize the atomized oil from the nozzle and achieve ignition. (See Chapter 9 for more information on Ignition Systems.) Chapter 1—Introduction to Oil Burners 1-7 to replace the motor with a new motor of the same rotation, frame size, and revolutions per minute (RPM). Figure 1-7 shows a motor, fan and coupling. The coupling attaches to the motor shaft on one end and the pump shaft on the other, taking power from the motor and transferring it to the pump. (Motors and couplings are covered in Chapter 10.) Figure 1-7: Motor, fan and coupling Multiblade fan and air shutter A fan wheel within the burner housing is driven directly by the motor shaft, and provides the necessary air to support combustion. An adjustable air shutter on the burner housing controls the volume of air handled by the fan. The oilburner fan, or blower wheel as it is often called, supplies the combustion air for the flame. See Figure 1-8. They are of the squirrel cage type with beveled blades that must be kept free of dirt and lint. The slightest amount of dirt will reduce the blade bevel and reduce the amount of air delivered. They are precision balanced and every effort must be made to prevent bending the wheel at its hub. A blower wheel with a bent or broken blade will be out of balance. This Figure 1-8: Oilburner fan or blower wheel Chapter 1 Intro to Oil Burners


NORA Oilheat Technicians Manual
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