UK trade guideBoiler Spares 5 min readUpdated 11 July 2026

How to Replace the Ignition Electrode on a Potterton Assure 30 (UK)

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

Potterton

The part

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

Isolate safely

Both electrodes on Potterton Assure 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 Potterton Assure 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?
Potterton Assure 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 Potterton Assure 30. Below 4 µA at steady state means clean or replace.
Do I need to notify the manufacturer?
Only if the Potterton Assure 30 is in warranty — Potterton require log of any part swap for labour claims.
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