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Vaillant Expansion Vessel 0020031984

Vaillant

Vaillant Expansion Vessel 0020031984

Expansion vessel for Vaillant VWS series appliances, absorbing thermal expansion to maintain system pressure.

At a glance

  • Appliance family: VWS series
  • Also known as 1381372
Manufacturer part no.
0020031984
Showing prices

£65.29

£54.41 ex. VAT · VAT at 20%

Available to order · 7 working days
Available to order · 7 working days
Not certain it's the right part? The technical team verifies fitment before dispatch — no charge, and it stops a second trip.Call the technical teamSend a technical question

Same-day dispatch

Ordered by 4pm Mon–Fri, 10:30am Sat.

30-day returns

Unused, in original packaging.

What it is

The Vaillant 0020031984 is an expansion vessel for Vaillant VWS series appliances. It absorbs the thermal expansion of water in a sealed heating system, limiting pressure rise as the system heats up. The vessel forms part of the appliance's hydraulic circuit.

Signs this part needs replacing

  • System pressure rises sharply when the appliance heats up and drops when cold.
  • Frequent topping up of system pressure is required.
  • Water discharges from the pressure relief valve during normal operation.
  • The vessel feels heavy or waterlogged when disconnected and shaken.
  • The pressure gauge reads high even when the system is cold.

Before you order

  • Confirm your appliance model against the fit list above.
  • Check the connection size and thread of the existing vessel match the replacement.
  • Verify the vessel's pressure rating matches the system requirements.
  • Ensure there is sufficient access and mounting space for the replacement.

Not sure which part?

Search by part number, product name or brand — our technical team confirms fitment before anything is dispatched.