Caleffi - 1/2" Series 309 Pressure & Temperature Relief Valve Set at 90°C - 10 Bar - 309400 CST

The Caleffi Series 309 Pressure & Temperature Relief Valve is a safety-critical mechanical fail-safe designed exclusively for unvented domestic hot water storage cylinders. Its primary function is to protect the structural integrity of the hot water tank by preventing the stored water from reaching a critical boiling state. If system safety controls fail and temperature or pressure thresholds are breached, the valve activates automatically, discharging a controlled volume of water to lower system energy and safely restore stable operating conditions.