Oil Boiler Servicing: What to Expect and How Often

How Often Should an Oil Boiler Be Serviced?

Oil boilers should be serviced once a year, ideally in summer or early autumn before the heating season begins. Unlike gas boilers, oil boilers tend to produce more soot and combustion residue, making regular cleaning even more important.

Servicing should always be carried out by an OFTEC-registered engineer (Oil Firing Technical Association) — the oil equivalent of Gas Safe for gas appliances.

What Does an Oil Boiler Service Include?

A thorough oil boiler service typically covers:

External Inspection

Checking the boiler casing and controls

Inspecting oil supply pipework and filter

Checking the oil storage tank condition (exterior inspection)

Checking flue terminal for obstructions

Internal Inspection and Cleaning

Cleaning or replacing the oil nozzle (sprays oil into the burner)

Cleaning the burner and combustion head

Cleaning the heat exchanger flue ways

Inspecting and cleaning the ignition electrodes

Checking and replacing the oil pump filter

Combustion Analysis

Using a flue gas analyser to check combustion efficiency

Adjusting air-to-fuel ratio for optimal efficiency and low emissions

Safety Checks

Testing the overheat thermostat

Checking all seals and gaskets

Checking flue integrity

Carbon monoxide test

Service Certificate

A signed service record is provided on completion, important for warranty and insurance purposes.

Why Oil Boiler Servicing Is Particularly Important

Oil combustion produces soot and carbon deposits more readily than gas. A blocked nozzle or dirty burner can cause:

Incomplete combustion, producing soot and CO

Reduced efficiency (higher fuel costs)

Boiler lockouts and breakdowns

Chimney/flue blockages (a fire risk)

What About the Oil Tank?

Your oil storage tank should also be inspected periodically by a qualified technician — looking for corrosion, leaks, and fuel quality. We recommend a tank inspection every 5 years at minimum.

Halo Heating carries out oil boiler servicing across West Sussex. Call us to book your annual service.