How to Replace the Fan on a Worcester Bosch Greenstar 32i (UK)
Step-by-step UK guide to replacing the combustion fan on a Worcester Bosch Greenstar 32i. Part numbers, torques, commissioning.
The part
Swap the combustion fan on Worcester Bosch Greenstar 32i when you get low-speed lockouts (F28/F29 Vaillant, EA Worcester, F1 Ideal) or bearing whine.
Isolate safely
Remove the case, disconnect the fan plug and Venturi. Note the fan's part number stamped on the motor housing.
Fit and commission
On Worcester Bosch Greenstar 32i the fan is torqued to 8–10 Nm — over-tightening cracks the composite plenum.
Recommission checklist
Refill the Worcester Bosch Greenstar 32i 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
- Which speed sensor connector?
- The Hall-effect sensor on Worcester Bosch Greenstar 32i uses a 4-pin JST plug. Do not swap L1/L2.
- Do I need a new gasket?
- Always fit the OEM Viton gasket — the old one hardens and leaks flue gases into the case.
- Do I need to notify the manufacturer?
- Only if the Worcester Bosch Greenstar 32i is in warranty — Worcester Bosch require log of any part swap for labour claims.
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