Installation, Service, and Troubleshooting
Installation, Service, and Troubleshooting
This domain tests commissioning and diagnosis: combustion testing, nozzle and electrode service, oil filtration, pump and coupling checks, control lockout diagnosis, draft and venting, and customer safety. Expect scenario questions with a symptom and a next test.
Core rules
- Commission with combustion analysis: draft, smoke, CO2 or O2, stack temperature, and CO. Adjust air to achieve clean combustion, then verify no CO in the living space.
- Service the oil filter and nozzle, check electrode condition and gap, inspect the combustion chamber, and verify pump pressure and coupling.
- Lockout after trial for ignition can come from no oil, air in the line, a clogged nozzle, weak ignition, or a dirty cad cell. Reset once, then test rather than repeatedly resetting.
- Delayed ignition and puffback point to oil accumulation, wrong electrode setting, low draft, or a bad nozzle. Soot and high smoke mean poor air/fuel ratio.
- Verify expansion tank charge, relief valve condition, feed pressure, air elimination, and circulator operation before seasonal startup.
Worked example
A burner runs, then locks out after about 30 seconds; the cad cell reads 2,500 ohms with flame visible. Since a flame should lower cad cell resistance, the high reading suggests a dirty or failing cell or poor sighting. Clean the cell, confirm it sees the flame, and recheck resistance; do not replace the primary control first. If resistance falls to a low value and the burner still locks out, test the control circuit and flame signal.
Traps
Do not reset a lockout repeatedly without finding the cause; do not replace a nozzle without a combustion test; do not ignore CO or draft; and do not assume a hot boiler means every zone has flow.