UK trade guideBoiler Spares 5 min readUpdated 11 July 2026

How to Replace the Ignition Electrode on a Baxi EcoBlue Plus 28 (UK)

Step-by-step UK guide to replacing the spark / ionisation electrode on a Baxi EcoBlue Plus 28. Part numbers, torques, commissioning.

Baxi

The part

Renew the ignition and flame-sense electrodes on Baxi EcoBlue Plus 28 when you get F27 / EA / L2 flame-detection faults after a clean burn.

Isolate safely

Both electrodes on Baxi EcoBlue Plus 28 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 EcoBlue Plus 28 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 EcoBlue Plus 28 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 EcoBlue Plus 28. Below 4 µA at steady state means clean or replace.
Do I need to notify the manufacturer?
Only if the Baxi EcoBlue Plus 28 is in warranty — Baxi require log of any part swap for labour claims.
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