The temperature and pressure release valve on a water heater is a safeguard feature in the event there is too much pressure or high of a temperature inside your water heater it will open and release some water and lower the pressure and temperature. This is an important feature that needs to work correctly as if the valve needs to open and cannot or fails, the water heater tank could explode causing property damage and risking bodily injuries. While the chances are slim of this happening as there needs to be a combination of the right conditions of pressure and hardware failure, the chances aren’t zero. One of the reasons for a TPR valve failing would be a clog from sediment or corrosion inside the tank which is why a flushing of the system should be done yearly.
If you have ever seen water on the floor by the water heater and you cannot find a leak or obvious sign of where the water came from, it’s mostly like due to the TPR doing its job and released water to lower the pressure or temperature. If this is the case it would be good to check and set the pressure and temperature to the ideal settings to ensure it doesn’t happen again and flush the system in case it happened due to debris or sediment buildup in the tank.
Caution: A professional should be called to perform maintenance and inspect the health of your water heater, if you are not comfortable in such tasks or have an older water heater that might not have obvious signs of damage. Check with your manufacturer’s warranty regarding maintenance to ensure you won’t void your warranty performing the maintenance yourself. Before performing the maintenance below, know where your main water shut off valve is and it’s in working order in the event something goes wrong to prevent further damage due to water damage.
TPR Valve usually will open at 150 psi, however it could be higher or lower depending on the water heater and valve installed. You can check the pressure by attaching a pressure gauge to your faucet, just be sure no other faucet or appliance is running water, or you may get false readings. Normal water pressure is between 40-60 psi; however, most will set it in the middle at 50 psi. Having water pressure too high can result in more water being used while running and pipes banging, and a lower pressure usually results in leaving the water running for longer while cleaning the dishes or showering.
Setting the temperature too high can result in scalding temperatures in showers and washing the dishes. It can also be a danger if you have kids who may turn on the hot water all the way and forget to test how hot the water is before using it. The EPA has recommended the temperature set to 120 degrees Fahrenheit or above to fight bacteria that may make you sick. Some dishwasher manufacturers recommend a temperature of 140 degrees Fahrenheit for cleaning and killing bacteria. Depending if you have children who may turn on the water too hot and burn themselves or other factors, you might want to set it lower but it’s recommend to set it to at least 120 degrees Fahrenheit or use a device called a booster which can mix hot water and cold after leaving the water heater tank to deliver desired safe temperature at the faucet while having a higher temperature in the water heater to kill bacteria.
To test the TPR valve simply raise the lever to allow water to flow down the drainpipe and out for about 5 seconds and then close it. If you don’t have a drainage system in place (very common), place a bucket underneath the drainpipe to catch the water and be aware the water will most likely be very hot and could splash out. If there is no drainpipe, call a plumber to install one. After you close the valve you shouldn’t have any more water coming from the drainpipe. Call a plumber if water leaks after closing the TPR valve as it’s a sign that the TPR valve isn’t working properly.