What is a TPR Valve?
Q: What is the brass valve on the side of my water heater for? A: It s called a TPR valve. All water heaters have a relief valve that is sensitive to both temperature and pressure. They are designed so that if the pressure inside the tank exceeds 150 lbs./sq. in., or the temperature exceeds 210 degrees, the valve will open and let some of the overheated water out. This lets cold water into the tank and decreases temperature and pressure. The valve stays open as long as the temperature or pressure exceeds those limits. While a tank failure from overpressure alone will cause water damage, a rupture due to the combination of temperature and pressure can be very dangerous. Q: What is the danger? A: It s physics. Water in the heater is always pressurized by the force in the supply line, so it can be heated to well above the 212 degrees that it takes to boil water at sea level and still be liquid. At 50 psi, the temperature of the water could reach 300 degrees or more. If a faulty thermostat
