1/2 m x 15mm Altecnic caleffi temperature and pressure relief valve 4 bar. The Altecnic 309 temperature - pressure relief valves are used to control and limit the temperature and pressure of hot water contained in a domestic storage cylinder, preventing the water from reaching 100?C.

When the set conditions are reached, the valve discharges a sufficient amount of water to allow the temperature or pressure to return within the systems operating limits.

The valves have been designed for use on unvented hot water systems.