General description The John Guest Speedfit Sp Underfloor Heating 11 Manifold Iso Valve is a durable replacement valve designed to control the flow of hot water in underfloor heating systems. It automatically opens the return port for the associated manifold circuit when in use and closes when the system is shut down, ensuring efficient operation. Technical specifications Material: Durable brass Compatibility: Suitable for JG Underfloor heating manifolds manufactured prior to April 2014