NATIONAL OILHEAT RESEARCH ALLIANCE

Oil Burner Service Troubleshooting

Follow the steps in order — verify and correct each issue before proceeding

Step 1 of 8 13%
Step 1 — Verify Call for Heat
Is the thermostat calling for heat?
START Call for HeatThermostat / 24V PowerSwitches / Voltage IgnitionSpark / Electrodes VerifyCombustion Correct Fault Repair / Recheck Retest Burner

Safety First

Turn off service switch before servicing. Never repeatedly reset a locked-out burner. Verify ventilation, oil leaks, and CO alarms.

Combustion Targets

O₂4.0–5.3%
CO₂11.5–13%
SmokeZero
CO< 100 ppm
Net Stack350–500°F
Excess Air25–35%

Common Lockout Causes

  • No flame or weak flame
  • Dirty or failed cad cell
  • Air in oil line
  • Low pump pressure
  • Bad nozzle or electrodes
  • Electrical fault

Draft Reminder

Measure over-fire and at the breech. Correct draft before final air adjustment and combustion testing.

NORA Technician Education & Technical Training