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NORA Oilheat Technicians Manual

the resistance from each ignitor post to ground, Figure 9-8. Normally, the ignitor is considered good if the resistance from each post to ground has no more than a 10% difference between posts. Each manufacturer is different and they should be consulted for the proper output range and differential. It’s also important that you verify continuity between the ignitor case ground and true ground. Another test that is approved by most manufacturers is to bring the ignitor output terminals to within ½ to ¾ of an inch apart and turn on the power, Figure 9-9. A strong blue spark should be generated. Another trick is to let it spark for a few minutes, five to ten in most cases, and see if the spark changes from blue to orange; if it does change, replace it. Finally, you can check both electronic ignitors and iron-core transformers with a common test. Bring the ignitor or transformer output terminals to within ½ to ¾ of an inch apart. Place a milliammeter in series with the hot line going to the ignitor and turn it on, Figure 9-10. Again, the reading should stay steady and not vary for at least five minutes with a strong blue spark throughout the test while staying within 10% of the rated amperage draw for the device. Cables, buss bars, spring clips In order to transport the high voltage from the secondary terminals of the ignition transformer, an effective and efficient path must be provided to the ignition electrodes. This path may be an ignition cable, buss bars, or spring type conductors. Ignition cables are normally constructed of heavy stranded copper wire covered with special heavy insulation to insulate against dampness, and ensure transmission around, over, or under any other conducting surface between the transformer location and the electrodes. The outstanding feature of ignition cables is flexibility, permitting easy handling, bending and installation in any burner. Some nozzle assemblies are equipped with clips to hold the flexible cable off the bottom of the burner air Figure 9-8: Ohmmeter test Chapter 9 Ignition Systems Figure 9-9: Spark test Figure 9-10: Milliammeter Chapter 9—Ignition Systems 9-11


NORA Oilheat Technicians Manual
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