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NORA Oilheat Technicians Manual

Troubleshooting Fuel Units Chapter 4 Fuel Units and Oil Valves No Oil Flow at Nozzle Oil level below intake line in supply tank. Fill tank with oil. Clogged strainer or filter Remove and clean strainer. Replace filter element. Clogged nozzle Replace nozzle. Air leak in intake line Tighten all fittings in intake line. Tighten unused intake port plug. Tighten in-line valve stem packing gland. Look for leaks in piping. Restricted intake line Replace any kinked tubing and check any valves in intake line. A two-pipe system that becomes air bound Check for bypass plug. A one-pipe system that becomes air bound Loosen gauge port plug, or open the bleed valve, start the burner, and drain oil until foam is gone. Check for high vacuum (over 6" vacuum). Check for air leaks in pump or oil line. Slipping or broken coupling Tighten or replace coupling. Air Leak Loose plugs or fittings. Dope with good quality thread sealer or pipe joint compound. Leak at pressure adjusting cap nut Fiber washer may have been left out after adjustment of pump pressure. Replace the washer. Blown seal—One-pipe system Check to see if bypass plug has been left in unit. Replace fuel unit. Blown seal—Two-pipe system Check for kinked tubing, rust in pump, or other obstructions in return line. Replace fuel unit. Check tank for water. Noisy Operation Bad coupling alignment, loosen fuel unit mounting screws slightly and shift unit in different positions until noise is eliminated. Retighten mounting screws or replace coupling. Pulsating Pressure Partially clogged strainer or filter. Remove and clean strainer. Replace filter element. Air leak in intake line Tighten all fittings and valve packing in intake line. Air leaking around cover Be sure strainer cover screws are tightened securely. Install a new gasket. Improper Nozzle Cut-Off To determine the cause of improper cut-off, insert a pressure gauge in the nozzle port of the pressure fuel unit. After a minute of operation, shut the burner down. If the pressure drops approximately 20% from normal operating pressure and holds at that pressure, the pump is operating properly and air is the cause of improper cut-off. If, however, the pressure drops more than 20% in 5 minutes, fuel unit should be replaced. Air pocket remaining in nozzle line Run burner, bled pump, stopping and starting unit, until smoke after disassembly and after-fire disappear. Air leak in intake line Tighten intake fittings and packing nut on shutoff valve. Tighten unused intake port plug. Partially clogged nozzle strainer Replace nozzle. Clean and flush out oil line and pump. 4-22 Fuel Units and Oil Valves


NORA Oilheat Technicians Manual
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