Combined or separate?

Potterton Promax 33 HE 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 Promax 33 HE. Below 4 µA at steady state means clean or replace.

Only if the Potterton Promax 33 HE is in warranty — Potterton require log of any part swap for labour claims.

Renew the ignition and flame-sense electrodes on Potterton Promax 33 HE when you get F27 / EA / L2 flame-detection faults after a clean burn.

Both electrodes on Potterton Promax 33 HE use ceramic insulators — never re-use if chipped.

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.

Refill the Potterton Promax 33 HE 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.

Combined or separate?: Potterton Promax 33 HE 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 Promax 33 HE. Below 4 µA at steady state means clean or replace.
Do I need to notify the manufacturer?: Only if the Potterton Promax 33 HE is in warranty — Potterton require log of any part swap for labour claims.

Shop the spares

Browse boiler spares — 14,820 live parts.