Nordyne O4HD-091A-12-FA Installation Instructions Manual page 27

Table C-4: System and General Troubleshooting
Problem
Excessive fuel oil
consumption.
Too much smoke.
Soot building up on blast
tube (end coning).
Furnace will not warm
home to desired
temperature.
Home does not heat
evenly
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continued
Possible Cause
System temperature rise too
high.
Poor "fan off" delay timing
selection, (fan stops too soon).
Fuel oil leak.
Stack temperature too high.
Thermostat improperly
adjusted or in poor location.
Insufficient combustion
adjustment at oil burner, or
improper draft pressure.
Heat exchanger partially
clogged.
Poor alignment between oil
burner blast tube and fire pot.
Flame impingement caused by
Incorrect nozzle angle.
Defective fire-pot
Airflow blocked or dirty air
filter.
Thermostat adjustments
location.
Insufficient airflow.
Defective high limit control.
Under-sized nozzle.
Blower fan motor stopping
intermittently on overload.
Burner motor stopping
intermittently on overload.
Improper distribution of heat.
System temperature rise ideally should not exceed 85°F. Check
for clogged air filters. Check blower fan for excess dirt build-up
or debris. Speed up blower fan if necessary.
Check "fan off" delay timing setting. Use a duct thermometer in
the supply air plenum take-off or first few inches of the supply
air trunk duct. Ideally, the fan will shut off at a temperature of
90° - 100°F. Manipulate the dip switch settings to come as close
as possible to this "fan off" temperature.
Check fuel oil line for leaks. Repair or replace if necessary.
Check stack temperature. Stack temperatures will normally
range from 350° to 450°F. Check draft regulator. Draft should
be set to 0.02 in. w.c.
Check thermostat heat anticipator setting against measured
amperage draw. Increase heat anticipator setting if necessary.
If the thermostat is being influenced by drafts, sunlight, duct
work, etc., relocate to more suitable location.
air Adjust the oil burner combustion air band and draft regulator to
gain the highest practical CO
the flue gases. See Burner Set Up.
Check for soot build-up in heat exchanger flue passages,
especially in the outer radiator.
Check alignment. Blast tube should be centered with fire pot
burner opening. Oil burner head should be ¼ inch back from the
inside surface of the fire pot.
Check nozzle size and angle. (See Appendix A). Check
distance from head to inside surface of the fire pot.
Check fire-pot. Repair or replace.
Clean or replace air filter.
Check thermostat heat anticipator setting against measured
or amperage draw. Increase heat anticipator setting if necessary.
If the thermostat is being influenced by drafts, sunlight, duct
work, etc., relocate to more suitable location.
Check all dampers. Open closed dampers including registers in
unused rooms. Check system temperature rise. If temperature
rise is too high, speed up blower fan.
Test high limit function of all limit switches. Use a duct
thermometer to assess accuracy of limit control. Check for
obstructions to airflow around limit switch bi-metal elements.
Replace control if necessary.
Check nozzle. If problem is not caused by air flow problems,
use larger nozzle, if permitted by rating plate.
Check blower fan motor amperage draw. Check motor
ventilation ports, clean if necessary. Replace motor if
necessary.
Check burner motor. Replace if necessary.
This is not likely to be a furnace problem. Balance duct system.
27
Remedy
or lowest practical O
2 2
151B0801 R5 3/28/2006
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