How to Replace the Flow Sensor on a Baxi 600 Combi 30 (UK)
Step-by-step UK guide to replacing the DHW turbine / flow sensor on a Baxi 600 Combi 30. Part numbers, torques, commissioning.
Baxi
The part
Swap the DHW turbine on Baxi 600 Combi 30 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 Baxi 600 Combi 30 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 Baxi 600 Combi 30 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 Baxi 600 Combi 30 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 Baxi 600 Combi 30 is in warranty — Baxi require log of any part swap for labour claims.
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