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C. Symptom: Burner short cycles on high limit thermostat, but does not “lock
out” on oil primary safety control.
Items to check:
1) Open dampers or registers in the air distribution system. Clear any
duct system restrictions.
2) Inspect and clean all air filters in the air distribution system.
3) Inspect blower for interference with rotation or locked rotor condition.
Also, confirm the blower wheel is secured to the fan motor shaft.
4) The fan motor or run capacitor may be damaged. Test and replace the
motor or capacitor, as required.
5) Increase fan speed.
D. Symptom: Unable to achieve clean combustion by making burner air
adjustments.
Items to check:
1) Measure the burner air tube insertion depth and alignment. The end of
the tube should not protrude inside the combustion chamber. The end
of the tube should be approximately ¼ inch away from the inner wall
surface of the combustion chamber.
2) Inspect the oil nozzle for excessive wear, blockage, or deterioration.
Measure and, if necessary, reset the nozzle depth or turbulator
location with respect to end of the burner head. Replace the nozzle, if
necessary (refer to the oil burner manufacturer’s instructions).
3) Measure the oil pump pressure. If required, adjust the pressure to
burner nameplate value. (This is the typical minimum pressure
required to obtain the full input rate from the furnace).
4) Verify the burner is configured as specified in Table 1 and adjusted
according to the Initial Burner Operation section of this manual and
the burner manufacturer’s instructions.
5) Measure the overfire draft. If required, adjust the barometric damper to
increase the stack draft to obtain an overfire draft of 0.02 in. W.G. with
the burner operating. (This is the typical minimum draft required to
obtain the specified flue gas combustion analysis values given in Table
1.) If the specified overfire draft cannot be obtained with a stack draft of
0.02 in. W.G., the heat exchanger may be partially blocked and could
require cleaning.