UK trade guideBoiler Spares 5 min readUpdated 11 July 2026

How to Replace the Ignition Electrode on a Baxi 600 Combi 30 (UK)

Step-by-step UK guide to replacing the spark / ionisation electrode on a Baxi 600 Combi 30. Part numbers, torques, commissioning.

Baxi

The part

Renew the ignition and flame-sense electrodes on Baxi 600 Combi 30 when you get F27 / EA / L2 flame-detection faults after a clean burn.

Isolate safely

Both electrodes on Baxi 600 Combi 30 use ceramic insulators — never re-use if chipped.

Fit and commission

Set the spark gap to 3.5–4.0 mm and the ionisation gap so the tip sits 4–5 mm above the burner surface.

Recommission checklist

Refill the Baxi 600 Combi 30 to 1.2 bar cold. Bleed high-point radiators and the internal AAV.

Run a full flue-gas analysis after 15 minutes. Log the reading against the OEM commissioning envelope in the Benchmark book.

Frequently asked questions

Combined or separate?
Baxi 600 Combi 30 runs a two-electrode kit — one spark, one sense. Fit both together to avoid a second call-back.
How do I test ionisation current?
In service mode read the µA value on Baxi 600 Combi 30. Below 4 µA at steady state means clean or replace.
Do I need to notify the manufacturer?
Only if the Baxi 600 Combi 30 is in warranty — Baxi require log of any part swap for labour claims.
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