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1. Start the unit. Use your eyes, ears, and nose. What is it doing? How long does it take? What does it smell like?
2. Start with a check of the chimney, flue, and draft regulator. Look at the flue passages and heat exchanger. Any soot or debris should be removed.
3. Check the combustion chamber. It should be self-supporting with no holes or cracks through to the outside. Soft ceramic chambers will typically show stress relief cracking on the inside, but this is not a sign of failure.
4. Replace the oil filter, gaskets, and nozzle. While the burner tray is removed, clean, inspect and set the electrodes. Also, inspect the gun assembly, air tube, burner retention head, combustion air wheel, and pump coupling.
5. Oil all motors and bearings, inspect the pulleys, and replace the air filters and belt if needed. At this point, the unit should be ready to check the limit, safeties, and operation.
6. A check of the ignition system safety controls is a must. Remove the wire from the blower motor and check ignition and flame size. During the ignition check, observe if the limit control shuts off the burner when the limit temperature setting is reached. Reconnect the blower motor and cool down the heat exchanger. Next check the primary control or stack switch to be sure they will shut the burner off if ignition is not detected.
7. Now the unit is ready for the combustion analysis. After the burner has been on steady for 10 minutes, check the stack temperature (CO2 or O2 test), draft over-fire, and perform a smoke test. (Compare the results with the combustion analyzer manufacturer tables.) The smoke test is very important. It can reveal a soot condition even if everything else looks OK.
8. Now the most important part of a service call - make sure the work area is cleaner when you leave than when you got there.
Author Ron Hunter is a technical service representative for Bard Manufacturing Co., Bryan, Ohio. For more information, visit www.bardhvac.com.
Publication date: 12/15/2003