Navien
Navien Thermal Fuse 30020776A
Thermal fuse for Navien NCB300 and NCB500 combi boilers, a safety cut-out that opens the circuit when temperatures exceed safe limits.
At a glance
- Appliance family: NCB300 and NCB500 series
£6.50
£5.42 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 Navien 30020776A is a thermal fuse used in Navien NCB300 and NCB500 combi boilers. It is a temperature-sensitive safety device that opens the electrical circuit when the surrounding temperature rises beyond its set limit, shutting the appliance down before heat damage occurs. Once the fuse has operated it does not reset and must be replaced.
Signs this part needs replacing
- The boiler fails to fire, with no heating or hot water.
- The appliance locks out and will not run after a reset attempt.
- A continuity test across the fuse shows an open circuit.
- The fuse body is discoloured, blistered or shows signs of localised heat damage.
- The boiler repeatedly shuts down once it reaches operating temperature.
Before you order
- Confirm the boiler model and serial number against the fit list above.
- Check the markings and rating on the existing fuse match the part being ordered.
- Isolate the electrical supply and the gas supply before carrying out any work.
- Establish and rectify the cause of the overheating before fitting a new fuse, otherwise the replacement will fail in the same way.
No specification data held for this part.
| Make | Model / assembly | Reference | Years | Fitment |
|---|---|---|---|---|
| NAVIEN NCB300-28K COMBI - (Serial Number 3710) | — | — | — | |
| NAVIEN NCB300-28K COMBI - (Serial Number 3710) | — | — | — | |
| NAVIEN NCB300-37K COMBI - (Serial Number 3734) | — | — | — | |
| NAVIEN NCB300-37K COMBI - (Serial Number 3734) | — | — | — | |
| NAVIEN NCB300-41K COMBI - (Serial Number 3711) | — | — | — | |
| NAVIEN NCB300-41K COMBI - (Serial Number 3711) | — | — | — | |
| NAVIEN NCB500-1S+/32K COMBI - (Serial Number 3924) | — | — | — | |
| NAVIEN NCB500-1S+/32K COMBI - (Serial Number 3924) | — | — | — | |
| NAVIEN NCB500-2S+/41K COMBI - (Serial Number 3712) | — | — | — | |
| NAVIEN NCB500-2S+/41K COMBI - (Serial Number 3712) | — | — | — |
Showing 10 of 12 compatible appliances.
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.
NAVIEN appliance manual — NCB300-28K COMBI - (Serial Number 3710), NCB300-37K COMBI - (Serial Number 3734), NCB300-41K COMBI - (Serial Number 3711)
manualmanualNAVIEN appliance manual — NCB500-1S+/32K COMBI - (Serial Number 3924), NCB500-2S+/41K COMBI - (Serial Number 3712), NCB500-2S/37K COMBI - (Serial Number 3735)
manualNo technical questions yet for this part.
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