The Vaillant 0020009866 is a genuine OEM temperature and pressure relief valve designed to provide essential safety protection for compatible Vaillant unvented cylinders, thermal stores, and hot water systems. This dual-function valve automatically releases water if temperature or pressure exceeds safe operating limits, preventing system over-pressurisation, overheating, and potential damage.

A failing T&P valve can lead to dangerous system pressure build-up, leaking discharge pipework, inconsistent hot water performance, or safety lockouts. Replacing it with a genuine Vaillant part ensures full compliance, safety, and long-term system reliability.

Key Features:

• Genuine Vaillant temperature & pressure relief valve

• Protects the system from overheating and over-pressurisation

• Automatically vents excess temperature or pressure

• Essential safety component for unvented hot water systems

• Manufactured to Vaillant’s strict OEM safety and quality standards

• Helps resolve leaking PRV issues, temperature faults & safety lockouts

• Durable, long-life brass and high-integrity internal components

• Direct-fit replacement for quick, safe installation

Compatibility

The Vaillant 0020009866 T&P Valve is compatible with:

• Selected Vaillant unvented cylinders

• Vaillant VUI storage combi units

• Vaillant thermal store systems

• Any appliance listing 0020009866 in the official Vaillant parts documentation

Engineers should always verify exact compatibility using the cylinder or system’s model-specific manual.