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Sime Rectangular Expansion Vessel 8 Litre 5183700

Sime

Sime Rectangular Expansion Vessel 8 Litre 5183700

Rectangular 8 litre expansion vessel for Sime gas boilers, with a 3/8 inch male connection.

At a glance

  • Also known as 2040154
Manufacturer part no.
5183700
Showing prices

£85.49

£71.24 ex. VAT · VAT at 20%

Available to order · 3 working days
Available to order · 3 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 Sime 5183700 is a rectangular expansion vessel with an 8 litre capacity and a 3/8 inch male connection. It is fitted to a range of Sime gas boilers, where it absorbs the expansion of water as the system heats up and maintains stable pressure across the sealed heating circuit.

Signs this part needs replacing

  • Boiler pressure rises sharply when the heating warms up and falls again when it cools.
  • Water discharges from the pressure relief valve during normal operation.
  • The vessel feels heavy or full of water when tapped, indicating a failed internal diaphragm.
  • System pressure will not hold and needs frequent topping up.
  • Visible corrosion or water weeping around the vessel connection.

Before you order

  • Confirm your boiler model against the fit list above.
  • Check the connection size on the existing vessel is 3/8 inch male.
  • Check the mounting position has clearance for a rectangular 8 litre vessel.
  • Verify the system pressure and expansion vessel charge are set correctly after fitting.

Not sure which part?

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