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NORA Oilheat Technicians Manual

Chapter 7 Combustion provide a written record that everything was as you say it was when you left the job. Measurement procedure Connect the flue gas sampling probe assembly to analyzer per manufacturer’s instructions. Verify the condensate trap plug is properly seated in combustion analyzer, and that water trap and thermocouple are not touching the side of the probe assembly. Before inserting the probe into the unit, start the analyzer and allow it to do its start up procedure. This is called the zeroing process. Never allow the 7-26 Combustion analyzer to zero in the stack unless manufacturer’s design allows this. As with older test equipment, measurements must be made in the stack between the barometric damper (if equipped) and the breech. Allow burner to operate until stack temperature stabilizes before testing. Observations to make before testing With experience, you will be able to quickly pinpoint the likely problems in the heating unit by looking at the instrument results, and making a few quick observations. • Look at the flame. Is it normally shaped? Is it lopsided? Is it striking the sides or floor of the combustion chamber? (Be sure the flame observation door is closed when you do your tests. The air flowing into the open door will lower the CO2 readings and raise the stack temperature.) • Check the burner-operating period. Burning periods of less than 5 minutes do not usually produce enough heat to give good results. Short burner operating periods can be caused by overfiring of unit, or by improper functioning of automatic electrical controls. • Watch the flame while the burner shuts down. A flame that lasts more than two seconds after the burner shuts off may be due to a poor cut-off. The primary two causes are air in the oil or the cut off in the fuel unit is defective. Refer to the Fuel Units Chapter for testing pump cut off. (Chapter 4). • Test for air leaks around the burner air tube, the combustion chamber and all access doors on the furnace. A common cause of low CO2 readings is air leaks into the unit. To see if the problem is air leaks, take a CO2 test over the fire. If it is higher


NORA Oilheat Technicians Manual
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