How to Replace the Ntc Sensor on a Worcester Bosch Greenstar Danesmoor 12/18 (UK)
Step-by-step UK guide to replacing the flow / return / DHW thermistor on a Worcester Bosch Greenstar Danesmoor 12/18. Part numbers, torques, commissioning.
The part
Replace an NTC thermistor on Worcester Bosch Greenstar Danesmoor 12/18 for wildly inaccurate flow temps or an F22/F75/L1 low-water fault.
Isolate safely
Each NTC on Worcester Bosch Greenstar Danesmoor 12/18 clips onto the copper flow pipe with a spring clip. Fit fresh heat-sink compound before refitting.
Fit and commission
Cross-check resistance with a multimeter — 10 kΩ at 25 °C for standard blue-body NTCs.
Recommission checklist
Refill the Worcester Bosch Greenstar Danesmoor 12/18 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 colour?
- Flow NTC is normally blue, return NTC red on Worcester Bosch Greenstar Danesmoor 12/18. Do not swap.
- Wire polarity?
- NTCs are non-polar — but keep leads clear of ignition HT leads.
- Do I need to notify the manufacturer?
- Only if the Worcester Bosch Greenstar Danesmoor 12/18 is in warranty — Worcester Bosch require log of any part swap for labour claims.
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