What is a TPR valve?
A temperature and pressure relief valve (TPR valve) is a safety device on storage water heaters that automatically releases hot water or steam when internal temperature or pressure exceeds safe limits, preventing tank rupture or explosion.
A TPR valve (temperature and pressure relief valve) is a critical safety component mounted on the side or top of a storage water heater tank. It opens automatically when either the internal water temperature climbs above 99 degrees Celsius or pressure rises above 80 psi, whichever occurs first, discharging excess hot water to prevent dangerous overpressure inside the tank.
The valve protects against two main failures. First, if a heater's thermostat malfunctions and water overheats, the TPR valve vents steam and scalding water before pressure builds enough to rupture the tank. Second, if normal thermal expansion occurs (water expands as it heats) with no expansion tank fitted, the TPR valve relieves pressure that would otherwise deform or rupture the vessel.
On most tanks, the TPR valve is located on the upper side or top of the cylinder, often with a discharge pipe running downward to drain released water safely away from people and property. Plumbers in Klang Valley installing or servicing hot water systems must ensure the TPR valve is correctly sized, positioned, and unobstructed. A faulty or missing TPR valve is a serious hazard and can invalidate warranties. If you notice water dripping from the discharge pipe or hear hissing from the tank, the valve may be opening due to excessive temperature or pressure and should be inspected by an experienced service technician.