Navien
Navien Packing DHW Heat Exchanger WRAS 20047738A
WRAS-approved packing seal for the Navien DHW heat exchanger, part 20047738A, used on NCB300 and NCB500 combi boilers.
£4.64
£3.87 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 packing for the DHW heat exchanger is a WRAS-approved sealing component fitted at the domestic hot water heat exchanger joint on Navien combi boilers. It seals the connection between the heat exchanger and the surrounding water circuit, preventing leakage at that joint. It is supplied as a single packing under part number 20047738A.
Signs this part needs replacing
- Water weeping or dripping from the DHW heat exchanger joint
- Damp patches, corrosion or limescale staining around the heat exchanger connections
- Gradual loss of system pressure with no other visible cause
- The packing appears hardened, flattened, cracked or deformed on inspection
- Slight seepage at the joint during hot water draw-off
Before you order
- Confirm your boiler model and serial number against the fit list above
- Check the position of the packing on the manufacturer's parts diagram for your appliance
- Inspect the joint for other seals or O-rings that may also need replacing at the same time
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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