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NORA Oilheat Technicians Manual

Chapter 4 Fuel Units and Oil Valves Chapter 4—Fuel Units and Oil Valves 4-11 Figure 4-14: Bleed valve Figure 4-15: Bleeder wrench the unit is mounted so that the oil supply line enters at the bottom of the unit, the inlet port plug in the cover may be loosened and removed. This will allow the oil to flow by gravity into the unit and fill the strainer chamber. Then the intake port plug should be replaced and the burner fired. If it is not possible to fill the strainer chamber in this manner, then the bleeder plug on the side of the regulating valve chamber should be loosened, the burner operated, and sufficient oil allowed to flow from this plug to purge the entire system of air until there is a steady stream of oil. If the pump has been completely drained of oil it may be necessary to remove the supply line and fill the unit with oil before adequate suction can be obtained. In the newer units, an Allen screw, or easy bleed plug, Figure 4-14, has been provided in this port to allow for bleeding. Continue to bleed the pump for 15 seconds after the last air bubble can be detected. After bleeding the unit, always check the flame for stability and burner shutdown to be sure all air has been purged from the system. Venting of air is normally not necessary in a two pipe system with a two stage pump, but may be done faster if the bleeder plug is opened to expel air. Vacuum power bleed If the oil lines run above the oil tank and back down to the burner (a siphon system) proper bleeding of the pump is crucial. To bleed a pump line and everything else all the way back to the tank, do the following: First fill the pump with oil. Place a hose over the bleeder. A device like the one shown in Figure 4-15 works well for this purpose. Open the bleeder one-half turn. Make sure that the open end of the bleed hose is immersed in oil in your pail or bucket. Close the inlet valve at the tank and start the burner. Wait until the pump starts to whine. If you have a vacuum gauge inserted, it will show 20" to 25" of vacuum. (If white smoke starts coming out of the hose, you didn’t fill the pump and the oil is burning.) Open the inlet valve and bleed for several minutes. After a tune-up, you would see some oil, then lots of bubbles and then air free oil. Once it’s bled out, close the bleeder with the pump running. Field pressure and cutoff checks Two of the most important service checks for a fuel unit are the output pressure check and the cutoff pressure


NORA Oilheat Technicians Manual
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