Baxi
Baxi Flow Sensor 7854145
Baxi 7854145 flow sensor supplied with 3/4" gaskets, for use with Aquaheat HD/HWI and HI/HWI appliances.
At a glance
- Also known as 1129402
£115.60
£96.33 ex. VAT · VAT at 20%
Same-day dispatch
Ordered by 4pm Mon–Fri, 10:30am Sat.
30-day returns
Unused, in original packaging.
What it is
The Baxi 7854145 is a flow sensor supplied with 3/4" gaskets. It is fitted to Baxi Aquaheat HD/HWI and HI/HWI appliances, where it detects water flow through the domestic hot water circuit and signals the boiler to fire on a draw-off. A working sensor is essential for reliable hot water demand detection.
Signs this part needs replacing
- No hot water demand detected when a tap or outlet is opened
- Boiler fails to fire or fires intermittently on a draw-off
- Hot water temperature fluctuating or running cold despite demand
- Flow-related fault indicated during hot water operation
- Leaks or weeping around the sensor body or its gasket joint
Before you order
- Confirm your appliance model against the fitment list above
- Check the connection size on the existing sensor is 3/4"
- Inspect the gasket seating face for damage before fitting
- Verify the fault is with the sensor rather than the wiring or PCB signal
Compliance
| Alternative numbers | 1129402 |
|---|
| Make | Model / assembly | Reference | Years | Fitment |
|---|---|---|---|---|
| BAXI AQUAHEAT HD/HWI 12/50 | — | — | — | |
| BAXI AQUAHEAT HD/HWI 12/50 WITH HEAT METER & MERCURIUS | — | — | — | |
| BAXI AQUAHEAT HI/ HWI - 4/50 | — | — | — | |
| BAXI AQUAHEAT HI/HWI - 14/50 | — | — | — |
Documents & drawings
Everything we hold for this part. Where a document exists but we don't hold it, the technical team will source it from the manufacturer — usually the same working day.
No documents held for this part. The technical team will source them from the manufacturer — usually the same working day.
No technical questions yet for this part.
Not sure which part?
Search by part number, product name or brand — our technical team confirms fitment before anything is dispatched.