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Table 13 – Heating Service Analysis
PROBLEM CAUSE REMEDY
Burners Will Not Ignite.
Misaligned spark e lectrodes.
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 a ttempting 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 connectio ns.
Burned---out heat anticipator in
thermostat.
Replace thermostat.
Broken thermostat wires. R un continuity check. Replace wires, if necessary.
Inadequate Heating.
Dirty air f il ter. Clean or replace filter as necessary.
Gas input to unit too low.
Check gas pressure at manifold. Clock gas meter for input.
If to o low, increase manifold pressure, or replace w ith
correct orifices.
Unit undersized f or application. Replace with proper unit or add additional unit.
Restricted airflow. Clean filter, rep lace 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.
Limitswitchcyclesmainburners.
Check rotation of blower, thermostat heat anti cipator
settings, and temperature rise of unit. Adjust as needed.
Too much outdoor air.
Adjust minimum position.
Check economizer operation.
Poor Flame
Character i stics.
Incomplete combustion (lack of
combustio n air) results in: Alde-
hyde odors, CO, sooting flame, o r
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 restrictio n. 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.
580J