The oil nozzle controls the spray pattern and amount of oil entering the burner. When it blocks, wears or becomes contaminated, the boiler can become smoky, unreliable or inefficient.

Key points

  • A nozzle is a precision part, not something to clean and reuse.
  • Symptoms include smoke, smell, rough starting and lockout.
  • The burner should be set up after nozzle replacement.
  • A blocked nozzle can point to oil contamination or missed servicing.

What the nozzle does

The nozzle atomises oil into a fine spray so it can ignite cleanly. The spray pattern, angle and flow rate have to suit the appliance and burner setup.

The wrong nozzle or a worn nozzle can affect combustion, efficiency and reliability.

Warning signs

Possible signs include repeated lockouts, smoky starts, soot, oil smell, rumbling, poor heat output or a burner that will not settle into a clean flame.

These symptoms can overlap with ignition, oil pressure and air setting faults, so diagnosis is still needed.

Why cleaning is not the answer

Nozzles are small precision components. Trying to clean one can damage the spray pattern and leave the boiler running badly.

During a proper service or repair, the correct replacement nozzle is fitted and the burner is checked afterwards.

Preventing repeat problems

Regular servicing, clean filters, good oil storage and attention to tank condition all help reduce contamination reaching the burner.

If nozzles block repeatedly, the wider oil supply should be considered, not just the burner.

Common questions

Can a blocked nozzle cause no heating?

Yes. If the nozzle cannot deliver the correct spray, the burner may fail to light or lock out.

Is nozzle replacement part of a service?

It can be, depending on the appliance, condition, service schedule and engineer judgement.