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NORA Oilheat Technicians Manual

Chapter 4—Fuel Units and Oil Valves 4-15 Figure 4-19: Oil leak test kit Chapter 4 Fuel Units and Oil Valves To do a visual test, use of a vacuum gauge and plastic tubing with fittings such as the Oil Watcher or Clearview, see Figure 4-19. Install the device between the pump, shut off valve and the suction line. Bleed all the air out of the lines, then run the unit and look for bubbles. One at a time, heading toward the tank, coat the fittings with lithium grease. The grease temporarily seals the leak. When the leaking fitting is covered, the air bubbles will disappear. Repair the leaking fittings and clean the grease off everything you have coated. An easier way to find leaks is by using an electronic sight glass. The electronic sight glass is a tool used by many air conditioning technicians. It is a hand held meter that has two transducers which you can easily mount at any point in your suction line. When operating, one transducer transmits and the other receives an ultrasonic signal. The pulse the signal receives tells the unit if there is air in the pipe. If it detects air, it makes a noise. When using the electronic sight glass, attach the sensors just prior to the first fitting in the line. If no air is detected, attach the sensors just past the same fitting and test again. Proceed in this manner until you arrive at a fitting with no air coming into it, but air after the fitting. You know that fitting is leaking. Continue on until all the leaks have been found. To check for leaks in the return line: More difficult to find is a leak in the return line. Over time, these can be the most troublesome leaks, because they can go for so long before being detected. When the burner is running, return lines can have up to five pounds pressure. This can add up to a lot of lost oil in a short time. The best way to check for a leaking return line is to hook the return line up to the suction side of the fuel unit and perform the operating vacuum test. The operating vacuum on the return line, when it is hooked to the pump as the suction line, should be about the same as the operating vacuum reading for the original suction line. If the vacuum is less than the return line, it is either leaking or the orginal suction line is partially plugged. The potential problem with this method is that the installer may not have run the return line all the way to the bottom of the tank. If you cannot draw oil up the return line you will not know if it is a big leak, or the line terminates at the top of the tank. Either way your next tool will be a shovel to dig up the top of the tank. (Do not hook up the suction line as a return, it could plug it up, or if there is a foot valve or other check valve in the line, it will blow the pump seal. Just vent the return oil into a bucket). If the operating vacuum is much less than the calculated vacuum or the operating vacuum of the suction line, look for air in the oil. If air is present, there is a good chance that you have a leak. Check all fittings and joints, as well as the optional inlet plug on the fuel unit. Be sure all flare fittings are done properly and there are no


NORA Oilheat Technicians Manual
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