Thermocouple
Johnson & Starley boiler thermocouple, 500mm (T111-500/M9)
Universal aftermarket pilot thermocouple, listed by the supplier as a Johnson & Starley type replacement.
At a glance
- Also known as 1700335
- Gas Safe registered engineer required for fitting
£18.56
£15.47 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
A pilot-flame safety thermocouple sold as a Johnson & Starley type replacement, catalogued under the reference T111-500/M9. It sits in the pilot flame and generates a small millivolt signal that holds the boiler's gas valve open, cutting the gas supply automatically if the pilot goes out.
Signs this part needs replacing
- Pilot light won't stay lit once the control knob is released
- Main burner won't ignite despite a visible pilot flame
- Weak or unstable millivolt reading on test
- Corrosion, scorching or a damaged lead
Before you order
- Match the part number on your existing thermocouple against T111-500/M9
- Isolate the gas supply before removing the old thermocouple
- Gas Safe registered engineer required for fitting
Compliance
| Alternative numbers | 1700335 |
|---|
No fitment data held for this part.
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.
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