Baxi Expansion Vessel Duotec 8 Litre 5114691

Rectangular 8 Litre Not for drinking water

The Baxi 8 Litre Expansion Vessel (5114691) is a genuine manufacturer replacement designed for use in Baxi Duotec combi and system boilers. The expansion vessel absorbs pressure increases within the central heating circuit as the system water heats and expands, protecting components such as the pump, heat exchanger, and PRV.

A failing or waterlogged expansion vessel can lead to rising pressure, PRV discharge, boiler lockouts, or loud system noises. Installing the correct 8L Baxi vessel restores safe and stable pressure regulation.

Key Features

• Genuine Baxi expansion vessel – 8 litre

• Designed for Baxi Duotec boilers

• Maintains stable system pressure during heating cycles

• Prevents pressure spikes, PRV discharge, and boiler faults

• Durable internal diaphragm for long-term reliability

• Direct-fit OEM replacement for fast installation

• Essential for correct heating system performance

Compatibility

• Designed for Baxi Duotec boiler models requiring an 8L internal expansion vessel

• Direct replacement for Baxi part number 5114691
  (If you want, I can list all compatible Duotec variants.)

When to Replace

• Pressure rises quickly when heating is on

• Boiler pressure drops to zero when cooling

• PRV repeatedly discharges water

• Vessel fails to hold charge or diaphragm has failed

• During major boiler servicing or refurbishment

Technical Specifications

• Manufacturer: Baxi

• Part Number: 5114691

• Capacity: 8 litres

• Type: Sealed system expansion vessel

• Connection: Boiler internal fitment

• Application: Central heating pressure stabilisation