How to Replace the Flow Sensor on a Ferroli Modena 32C (UK)
Step-by-step UK guide to replacing the DHW turbine / flow sensor on a Ferroli Modena 32C. Part numbers, torques, commissioning.
Ferroli
The part
Swap the DHW turbine on Ferroli Modena 32C when hot water runs cold at low flow or the boiler fails to fire on demand.
Isolate safely
Isolate cold mains at the boiler's blue isolator. The sensor on Ferroli Modena 32C clips into the hydraulic block with two retaining clips.
Fit and commission
Fit new O-rings and align the turbine so the flow arrow matches the cold mains direction.
Recommission checklist
Refill the Ferroli Modena 32C 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
- Can I clean rather than replace?
- Yes for a limescaled unit — soak the turbine in citric acid, but replace if the Hall-effect PCB is corroded.
- What minimum flow triggers?
- The Ferroli Modena 32C typically ignites at 2.5 L/min. Below that, check the aerator on the DHW outlet.
- Do I need to notify the manufacturer?
- Only if the Ferroli Modena 32C is in warranty — Ferroli require log of any part swap for labour claims.
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