UK trade guideBoiler Spares 5 min readUpdated 11 July 2026

How to Replace the Pcb on a Glow-worm Compact 24c (UK)

Step-by-step UK guide to replacing the printed circuit board on a Glow-worm Compact 24c. Part numbers, torques, commissioning.

Glow-worm

The part

Replace the main control PCB — the most common cause of no-heat, no-DHW and intermittent lockouts on Glow-worm Compact 24c.

Isolate safely

Isolate at the fused spur and lock off. Discharge any residual mains voltage before touching connectors.

Fit and commission

Photograph every plug and its position on the Glow-worm Compact 24c PCB before unclipping — connector positions differ subtly across firmware revisions.

Recommission checklist

Refill the Glow-worm Compact 24c 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

PCB part number location?
On Glow-worm Compact 24c the PCB label is on the top-right of the board, printed as an 0020-series code. Match every digit.
Do I need to re-parameterise?
Yes — enter the correct boiler model code in the service menu after fitting so the ignition curve, fan speed and gas rate match.
Do I need to notify the manufacturer?
Only if the Glow-worm Compact 24c is in warranty — Glow-worm require log of any part swap for labour claims.
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