What is a TPR valve?
A TPR valve (temperature and pressure relief valve) is a safety device on water heaters that opens to release excess pressure and heated water when either temperature or pressure inside the tank exceeds safe operating limits.
A TPR valve, or temperature and pressure relief valve, sits on the side or top of a water heater tank and acts as a critical safety mechanism. When water inside the tank heats to dangerous temperatures or pressure builds beyond the tank's design limits, the valve automatically opens and discharges water through a drain line to relieve that excess.
Water heaters heat water to around 120-140 degrees Fahrenheit under normal conditions. If a thermostat fails or pressure accumulates from a closed system, the tank could rupture or even explode without relief. The TPR valve prevents this by triggering at preset thresholds, typically 150 degrees Fahrenheit or 80 pounds per square inch (psi) of pressure, whichever occurs first.
A properly functioning TPR valve should weep slightly or discharge water occasionally, especially after heating cycles. Frequent or continuous discharge usually signals a problem with the thermostat, a malfunctioning valve, or excessive system pressure. Conversely, a valve that never discharges at all may be stuck closed and unable to protect the tank.
Ontario plumbers regularly inspect TPR valves during routine water heater maintenance and repairs. A faulty or missing TPR valve is a serious safety hazard and should be replaced immediately.