Page 221

NORA Oilheat Technicians Manual

Chapter 10 Motors Figure 10-20: Pulley belts Chapter 10—Motors 10-15 Figure 10-21 the bearing assembly shaft. Figure 10-23 shows a three-piece circulator. Circulator motors often are PSC motors, as shown on page 10-9. Circulator couplings These are used on threepiece circulators to couple the motor to the circulator pump. See Figure 10-23. These can wear and break. Excessive oiling of the circulator can cause the rubber motor mounts to sag, causing the coupling to break; therefore check motor mounts when replacing the coupling. The motor mounts need to be replaced if they have softened. On some of these circulators, the coupling has tension pulling the shaft toward the motor with a spring. This holds pressure on the water seal in the circulator. Care should be taken to maintain this pressure during the change, or water will leak out around the circulator shaft. It is best to reduce the water pressure on the boiler while changing this type. Figure 10-23: Three-piece circulator Figure 10-22: Cartridge circulator Power Pack Coupler Bearing Assembly Impeller Pump Body Direct drive blowers These are blowers with the motor mounted inside the wheel of the blower with the shaft of the blower connected directly to the blower wheel. Some of these are multi-speed PSC motors. In this case, speed is adjusted by swapping the wires as indicated on the wiring diagram on the blower. On both types of blowers, it is important that the blower, Figure 10-21, is clean and in good repair. Dirty, bent or broken blades on the blower can cause excessive amperage draw due to increased load. Broken or bent blades can cause vibration, as the blower will be out of balance. Circulator motors Hot water heating systems rely on circulator pumps to move the hot water through the heating system. There are two kinds: cartridge and three-piece circulators. With cartridge units, the pump impeller is fastened directly to the motor shaft as shown in Figure 10-22. Three-piece circulators feature a bearing assembly that connects the motor to the pump body. The bearing assembly shaft is connected to the motor shaft by a pump coupling. The pump impeller is fastened to


NORA Oilheat Technicians Manual
To see the actual publication please follow the link above