Can I clean the old one?

Rinse and refit if the trap body is undamaged, but always fit new seals.

22 mm external pipe rule?

Yes — post-2018 the run outside the wall must be 32 mm insulated per BS 6798.

Only if the Worcester Bosch Greenstar 24i is in warranty — Worcester Bosch require log of any part swap for labour claims.

Renew the internal condensate trap on Worcester Bosch Greenstar 24i when you get D5, F1 or E133 pressure-switch faults after a service.

The trap on Worcester Bosch Greenstar 24i snaps into the case bottom — flood with clean water before refitting to prime the U-bend.

Check the external condensate pipe fall (2.5° minimum) at the same time to avoid a repeat freeze-up.

Refill the Worcester Bosch Greenstar 24i 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.

Can I clean the old one?: Rinse and refit if the trap body is undamaged, but always fit new seals.
22 mm external pipe rule?: Yes — post-2018 the run outside the wall must be 32 mm insulated per BS 6798.
Do I need to notify the manufacturer?: Only if the Worcester Bosch Greenstar 24i is in warranty — Worcester Bosch require log of any part swap for labour claims.

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