The Vaillant 0020009864 is a genuine OEM pressure reduction valve designed to regulate incoming cold water pressure for compatible Vaillant unvented cylinders, storage combi units, and thermal store systems. This valve ensures the system receives water at a safe, controlled pressure, protecting internal components and maintaining consistent hot water performance.

A faulty pressure reduction valve can cause high system pressure, noisy operation, leaking relief valves, slow hot water flow, or fluctuating performance. Installing this genuine Vaillant replacement ensures stable pressure control and long-term system reliability.

Key Features:

• Genuine Vaillant pressure reduction valve

• Regulates and stabilises incoming water pressure

• Protects cylinder and system components from over-pressure

• Ensures consistent and efficient hot water delivery

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

• Helps resolve pressure issues, noise & performance instability

• Durable, long-life construction

• Direct-fit replacement for professional servicing

Compatibility

The Vaillant 0020009864 Pressure Reduction Valve is compatible with:

• Selected Vaillant unvented cylinders

• Vaillant VUI storage combi systems

• Vaillant thermal stores

• Any appliance listing 0020009864 in the official Vaillant parts documentation

Installers should always confirm compatibility using the system’s model-specific manual or parts list.