UK trade guideBoiler Spares 5 min readUpdated 11 July 2026

How to Replace the Ntc Sensor on a Ideal Independent 30 (UK)

Step-by-step UK guide to replacing the flow / return / DHW thermistor on a Ideal Independent 30. Part numbers, torques, commissioning.

Ideal

The part

Replace an NTC thermistor on Ideal Independent 30 for wildly inaccurate flow temps or an F22/F75/L1 low-water fault.

Isolate safely

Each NTC on Ideal Independent 30 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 Ideal Independent 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

Which colour?
Flow NTC is normally blue, return NTC red on Ideal Independent 30. 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 Ideal Independent 30 is in warranty — Ideal require log of any part swap for labour claims.
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