How to Replace the Fan on a ATAG iC Economiser 35 (UK)
Step-by-step UK guide to replacing the combustion fan on a ATAG iC Economiser 35. Part numbers, torques, commissioning.
ATAG
The part
Swap the combustion fan on ATAG iC Economiser 35 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 ATAG iC Economiser 35 the fan is torqued to 8–10 Nm — over-tightening cracks the composite plenum.
Recommission checklist
Refill the ATAG iC Economiser 35 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 ATAG iC Economiser 35 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 ATAG iC Economiser 35 is in warranty — ATAG require log of any part swap for labour claims.
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