Vaillant Boiler Expansion Vessel 181051 + Pressure Relief Valve 96008LA

Product Overview

The Vaillant Boiler Expansion Vessel 181051 with Pressure Relief Valve (PRV) 96008LA is a replacement hydraulic safety component kit designed for use within selected Vaillant heating systems.

The expansion vessel is a key component of a sealed heating system. It absorbs the increase in water volume as the system temperature rises, helping to maintain stable operating pressure. The pressure relief valve (PRV) provides additional protection by releasing excess system pressure when required, helping prevent pressure-related damage to the boiler and heating system.

ℹ️ Product Condition Options:

This part may be available in New or Refurbished condition. Please check the available options from the dropdown menu.

Technical Insight & Common Failure Symptoms

The expansion vessel contains an internal diaphragm and air chamber that manages pressure changes within a sealed heating system. Over time, the diaphragm can deteriorate or the vessel may lose its charge, reducing its ability to control system pressure.

The pressure relief valve is a safety device designed to discharge water if the boiler pressure rises above the safe operating level. A faulty PRV may leak or fail to reseal correctly after operation.

Typical symptoms linked to a faulty expansion vessel or PRV include:

• Boiler pressure rising excessively when heating is operating
• Pressure relief valve leaking or discharging water
• Frequent need to repressurise the heating system
• Boiler pressure dropping after operation
• Water escaping from the PRV discharge pipe
• Pressure-related boiler faults or lockouts

Replacing the expansion vessel and PRV together may help restore stable system pressure and reliable boiler operation.

Compatibility

Manufacturer Part Numbers (MPN):

• 181051 – Expansion Vessel
• 96008LA – Pressure Relief Valve (PRV)

This part is designed for selected models within the Vaillant range.

Please strictly verify the manufacturer part numbers 181051 and 96008LA against your boiler's technical manual, exploded parts diagram, or existing components before ordering to guarantee correct fitment.

Safety Advice

Boiler pressure components involve water, heating system pressure, and internal boiler assemblies. Installation and servicing must be carried out by a Gas Safe registered engineer in accordance with current regulations and manufacturer instructions.