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Burner Troubleshooting
Table 9 - Burner Troubleshooting Chart
Problem Potential Cause Corrective Action
Pilot Does Not Light/Stay Lit
Main gas is off Open main gas valve.
Air in gas line Purge gas line.
Dirt in pilot orifice Clean orifice with compressed air.
Gas pressure out of range Adjust to proper gas pressure.
Pilot valve is off Turn pilot valve on.
Leak at pilot orifice Tighten pilot orifice.
Excessive drafts Redirect draft away from unit.
Safety device has cut power Check limits and airflow sensor.
Dirty flame sensor Clean flame sensor.
No call for heat Adjust heat setpoint.
No spark at igniter
Check wiring, sensor, and ignition
controller. Check spark gap, refer
to Figure 19 on page 32.
Main Burner Does Not Light
(Pilot is lit)
Defective valve Replace combination valve.
Loose valve wiring Check wiring to valve.
Defective flame rod Replace flame rod.
Shut off valve closed Open shut off valve.
Defective flame safety controller Replace flame safety controller.
Pilot fails as main gas valve
opens, and main gas flows.
Plug the first burner port next to
the pilot gas tube with burner
cement.
Not Enough Heat
Main gas pressure too low
Increase main gas pressure - do
not exceed 14 inches wc inlet
pressure(5-14” wc).
Too much airflow Decrease airflow if possible.
Burner undersized Check design conditions.
Gas controls not wired properly Check wiring.
Heat setpoint too low Increase heat setpoint.
Thermostat malfunction
Check Wiring. Replace
Thermostat.
Unit locked into low fire Check wiring.
Too much heat
Defective modulating gas valve Check/replace modulating valve.
Heat setpoint too high Decrease heat setpoint.
Unit locked into high fire Check wiring.
Thermostat malfunction
Check Wiring. Replace
Thermostat.
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