Nordyne O4HD-091A-14-FA-DV Installation, Operation And Maintenance Manual page 29

Table C-4: System and General Troubleshooting continued
Problem Possible Cause
System temperature rise too
high.
Poor "fan off" delay timing
selection, (fan stops too soon).
Remedy
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 wilt 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.
Excessive fuel oil
consumption. Fuel oil leak.
Stack temperature too high.
Check thermostat heat anticipator setting against measured
Thermostat improperly amperage draw. Increase heat anticipator setting if necessary.
adjusted or in poor location. If the thermostat is being influenced by drafts, sunlight, duct
work, etc., relocate to more suitable location.
Insufficient combustion air Adjust the oil burner combustion air band and draft regulator to
adjustment at oil burner, or gain the highest practical CO2 or lowest practical 02 content in
Too much smoke, improper draft pressure, the flue gases. See Burner Set Up.
Heat exchanger partially Check for soot build-up in heat exchanger flue passages,
clogged, especially in the outer radiator.
Check alignment. Blast tube should be centered with fire pot
Poor alignment between oil
burner opening. Oil burner head should be ¼ inch back from the
Soot building up on blast burner blast tube and fire pot. inside surface of the fire pot.
tube (end coning). Flame impingement caused by Check nozzle size and angle. (See Appendix A). Check distance
Incorrect nozzle angle, from head to inside surface of the fire pot.
Defective fire-pot Check fire-pot. Repair or replace.
Airflow blocked or dirty air
Clean or replace air filter.
filter.
Check thermostat heat anticipator setting against measured
Thermostat adjustments or amperage draw. Increase heat anticipator setting if necessary.
location. 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
Insufficient airflow, unused rooms. Check system temperature rise. If temperature
Furnace wilt not warm rise is too high, speed up blower fan.
home to desired Test high limit function of all limit switches. Use a duct
thermometer to assess accuracy of limit control. Check for
temperature. Defective high limit control, 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
Under-sized nozzle.
larger nozzle, if permitted by rating plate.
Blower fan motor stopping Check blower fan motor amperage draw. Check motor
intermittently on overload, ventilation ports, clean if necessary. Replace motor if necessary.
Burner motor stopping Check burner motor. Replace if necessary.
intermittently on overload.
Home does not heat
evenly Improper distribution of heat. This is not likely to be a furnace problem. Balance duct system.
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