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NORA Oilheat Technicians Manual

a good possibility that lack of overfire draft is causing the trouble. Refer to Chapter 6— ‘Chimneys & Draft.’ Puffbacks and carbon may be caused by a partially clogged nozzle. See Chapter 5 on Nozzles. 11. Ignition “on” time should be checked. This, of course, concerns interrupted ignition primary controls. The ignition “on” time is easily checked by connecting one lead of a 40-watt test light to the ignition wire of the primary, and connecting the other lead to neutral or the white wire. Start the burner while watching the bulb time to determine the length of time it remains “on.” With cad cell type controls, it should remain on for the length of time specified by the manufacturer. Ignition Control Most burner manufacturers today use interrupted ignition. On commercial/ industrial burners, ignition “on” times of greater than 10-20 seconds are seldom found. The purpose of interrupted ignition is to ignite the fuel and shut off the system, prolonging ignition system component life. For example, let us say that a residential burner that consumes 1,000 gallons per year is operating with a 1 GPH nozzle. For this example, let us assume the burner will start 3,000 times per year. Example 1 Intermittent ignition = ignition is on when burner runs. 1000 gallons / 1 GPH = 1000 hours of ignition on time. Example 2 Interrupted ignition = timed or sequenced ignition. Cad-cell type relays 3000 starts x 45 seconds = 37.5 hours ignition on time 3000 starts x 30 seconds = 25 hours 3000 starts x 15 seconds = 12.5 hours 3000 starts x 8/10 seconds = 40 minutes ignition on time As we can see, we can dramatically lower ignition on-time and prolong the useful life of our ignition systems and reduce service calls. Delayed ignition is one of the frustrating ignition problems we encounter. Some solutions are covered in the following charts provided by Beckett Corp., Figure 9-14: Ignition Service Help Chart and Figure 9-15: Delayed Ignition Problem Solving, on following pages. Chapter 9 Ignition Systems Chapter 9—Ignition Systems 9-15


NORA Oilheat Technicians Manual
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