SPECIAL OFFERS
Onyx 18L White Potable Vessel 3/4 2 Bar ONYX18LPOT
Onyx 18 litre white potable water expansion vessel with a 3/4 inch connection and 2 bar pre-charge.
At a glance
£25.64
£21.37 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 Onyx 18L White Potable Vessel is an expansion vessel for potable water systems, supplied with a 3/4 inch connection and a 2 bar pre-charge. It absorbs the expansion of heated water within a sealed system, limiting pressure rise and protecting downstream components. The white finish distinguishes it as a potable water vessel within the Onyx expansion vessel range.
Signs this part needs replacing
- Water discharging from the system pressure relief valve during heat-up
- System pressure rising sharply when the cylinder or boiler heats and dropping when it cools
- Water weeping from the air valve or Schrader connection on the vessel
- Visible corrosion, blistering or pinholing on the vessel shell
- Loss of pre-charge, confirmed by a low or zero reading at the air valve
Before you order
- Confirm the connection size on the existing vessel matches 3/4 inch
- Check the pre-charge pressure required by the system against the 2 bar rating
- Verify the vessel is intended for potable water service, not sealed heating only
- Measure the available installation space, including clearance for the connection and any mounting bracket
No specification data held for this part.
| Make | Model / assembly | Reference | Years | Fitment |
|---|---|---|---|---|
| SPECIAL OFFERS Pressure Vessels & Accessories | — | — | — |
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.
No technical questions yet for this part.
Not sure which part?
Search by part number, product name or brand — our technical team confirms fitment before anything is dispatched.