UK trade guideBoiler Spares 5 min readUpdated 11 July 2026

How to Replace the Siphon Trap on a Baxi EcoBlue Advance 28 (UK)

Step-by-step UK guide to replacing the condensate siphon on a Baxi EcoBlue Advance 28. Part numbers, torques, commissioning.

Baxi

The part

Replace the condensate siphon on Baxi EcoBlue Advance 28 for D5 / F1 pressure faults after a hard frost or heavy servicing schedule.

Isolate safely

Isolate, drop the case front. Undo the siphon quick-release clip on Baxi EcoBlue Advance 28, tip out old fluid.

Fit and commission

Prime the new siphon with 250 mL clean water before refitting — dry siphons throw immediate flue-pressure faults.

Recommission checklist

Refill the Baxi EcoBlue Advance 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

Interval?
Inspect annually at service; replace at 5-year mark or after any freeze event.
Can I fit generic?
No — use OEM only; the seal geometry on Baxi EcoBlue Advance 28 varies between production years.
Do I need to notify the manufacturer?
Only if the Baxi EcoBlue Advance 28 is in warranty — Baxi require log of any part swap for labour claims.
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