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32
Table 13 – Heating Service Analysis
PROBLEM
CAUSE
REMEDY
Burners Will Not Ignite.
Misaligned spark electrodes.
Check flame ignition and sensor electrode positioning.
Adjust as needed.
No gas at main burners.
Check gas line for air, purge as necessary. After purging
gas line of air, allow gas to dissipate for at least 5 minutes
before attempting to relight unit.
Check gas valve.
Water in gas line.
Drain water and install drip leg to trap water.
No power to furnace.
Check power supply, fuses, wiring, and circuit breaker.
No 24 v power supply to control
circuit.
Check transformer. Transformers with internal overcurrent
protection require a cool down period before resetting.
Miswired or loose connections.
Check all wiring and wire nut connections.
Burned---out heat anticipator in
thermostat.
Replace thermostat.
Broken thermostat wires.
Run continuity check. Replace wires, if necessary.
Inadequate Heating.
Dirty air filter.
Clean or replace filter as necessary.
Gas input to unit too low.
Check gas pressure at manifold. Clock gas meter for input.
If too low, increase manifold pressure, or replace with
correct orifices.
Unit undersized for application.
Replace with proper unit or add additional unit.
Restricted airflow.
Clean filter, replace filter, or remove any restrictions.
Blower speed too low.
Use high speed tap, increase fan speed, or install optional
blower, as suitable for individual units.
Limit switch cycles main burners.
Check rotation of blower, thermostat heat anticipator
settings, and temperature rise of unit. Adjust as needed.
Too much outdoor air.
Adjust minimum position.
Check economizer operation.
Poor Flame
Characteristics.
Incomplete combustion (lack of
combustion air) results in:
Aldehyde odors, CO, sooting
flame, or floating flame.
Check all screws around flue outlets and burner
compartment. Tighten as necessary.
Cracked heat exchanger.
Overfired unit — reduce input, change orifices, or adjust
gas line or manifold pressure.
Check vent for restriction. Clean as necessary.
Check orifice to burner alignment.
Burners Will Not Turn
Off.
Unit is locked into Heating mode
for a one minute minimum.
Wait until mandatory one---minute time period has elapsed
or reset power to unit.
48L
C
Summary of Contents for 48LC 05
Page 10: ...10 COOLING CHARGING CHARTS C14037 Fig 13 Cooling Charging Charts 3 Ton 48LC ...
Page 11: ...11 COOLING CHARGING CHARTS cont C14038 Fig 14 Cooling Charging Charts 4 Ton 48LC ...
Page 12: ...12 COOLING CHARGING CHARTS cont C14039 Fig 15 Cooling Charging Charts 5 Ton 48LC ...
Page 35: ...35 WIRING DIAGRAMS C14043 Fig 44 Unit Wiring Diagram Power 208 230V 460V 3 Phase 48LC ...
Page 36: ...36 C14044 Fig 45 Unit Wiring Diagram Power 575V 3 Phase 48LC ...
Page 37: ...37 C14045 Fig 46 Unit Wiring Diagram Control 48LC ...
Page 47: ...47 48LC ...