How to Replace a Boiler Condensate Trap (UK)
Fit a new condensate siphon trap on Worcester, Vaillant, Baxi and Ideal boilers. Cures E133/F28 recycling faults.
Worcester BoschVaillantBaxiIdeal
Why the trap fails
Modern condensing boilers produce 2 L/day of acidic condensate. The trap seals combustion gases from the drain. Sludge (calcium carbonate + carbon) blocks the siphon within 3–5 years.
OEM part numbers
- Worcester Greenstar — 87161029130.
- Vaillant ecoTEC — 0020155086.
- Baxi 800 — 720072201.
- Ideal Logic — 173950.
Clean vs replace
Descale with a kettle-desalter first. If the plastic is discoloured (brown-yellow), replace — the acid has weakened the shell.
Frequently asked questions
- Can I run the boiler with the trap removed?
- Absolutely not. CO can enter the property via the drain. Isolate until refitted.
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