Oil Heating Installation and Maintenance
Core concepts
Oil heating work centres on the pressure-jet burner, the oil supply line, the combustion process and the controls that sequence it. A candidate must understand:
- Fuel grades and storage: kerosene (28-second oil) for vaporising and some pressure-jet appliances, and gas oil (35-second oil) for larger pressure-jet burners. Storage tanks, bunding, fire separation, fill-point labelling and the requirement for a tank gauge and vent are recurring topics. Know the difference between single-skin and integrally bunded tanks and when bunding is required.
- Supply systems: two-pipe (ring and return) versus single-pipe (dead-end) arrangements, the role of the de-aerator, oil line sizing, and the fire valve location (remote from the appliance, with the sensor in the combustion chamber area).
- Combustion and settings: nozzle sizing and spray pattern, pump pressure, air damper setting, and the flue gas analysis. Smoke number, CO2, flue temperature and CO are the four readings that drive commissioning and fault diagnosis.
- Sequence of operation: call for heat, burner motor and pump, ignition, flame detection (photocell), lockout timer, and the safety shut-down path.
Traps
Questions often test the purpose of a component rather than its name: for example, why the fire valve sensor sits at the appliance rather than at the tank, or why a de-aerator is needed on a two-pipe system. Watch for confusion between lockout and flame-failure, and between nozzle size (flow) and angle (spray pattern).
Rule of thumb
A smoky flame with a high CO2 reading and low flue temperature usually points to too much oil or too little air - check nozzle size and pump pressure before touching the air damper.