4-16 Fuel Units and Oil Valves Figure 4-20: Dirty strainer Chapter 4 Fuel Units and Oil Valves Nozzle discharge port location For ease of installation, fuel units are built with both right and left-hand nozzle or discharge ports. Again, a right or left hand port location is determined by holding the unit with the shaft pointing toward you. Shaft sizes Most oil pumps have either a 5/16" shaft or a 7/16" shaft. The smaller shaft may be bushed up for substitute replacement. Installation requirements Be sure that the replacement unit is properly mounted and in line with the motor coupling. The Allen screws or flange mounting bolts, which hold the fuel unit to the burner housing, must be securely tightened. If the coupling between the motor and the fuel unit has Allen set screws, these should be securely tightened against the motor shaft, after tightening unit-mounting bolts. To do otherwise may result in a jammed coupling and damage to the pump or the motor may occur. Pump strainers It is necessary to periodically clean the fuel unit strainer, Figure 4-20. To clean or replace the strainer, loosen the strainer compression fittings. Be sure all oil lines that go through a wall or under concrete are sheathed in plastic tubing. Be sure to use non-hardening oil pipe dope on threads. Do not use Teflon® tape on fittings; it will void the pump warranty. Selection of replacement fuel units It is good general practice to replace a fuel unit with one of a similar type, unless you have determined that there is a mismatch between the fuel unit capacities and the operating requirements of the burner. Fuel unit manufacturers attach identification plates to their units. These plates contain serial numbers that identify the units and their operational characteristics. Reference material for these identifying serial numbers is available from the manufacturers and should be included in your burner service data, as it will make selection of proper replacement units easier. When replacing fuel units, consider the following. Shaft rotation Pumps are designed for either clockwise (CW) or counterclockwise (CCW) rotation and proper rotational direction is shown on the unit identification plate. With the unit shaft held toward you, clockwise rotation will be to the right, often shown by an arrow pointing to the right. Counterclockwise to the left, with an arrow pointing left. This rotation must be matched to the burner motor. Rotational speed The great majority of older domestic oilburner motors operate at a speed of 1725 RPM, while most flame retention burners operate at 3450 RPM. Pump speed should be matched to motor speeds.
NORA Oilheat Technicians Manual
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