Temperature pressure relief (TPR) valves are safety devices installed on hot water heaters. These devices are designed to automatically discharge hot water in the event the temperature or pressure inside the water heater reaches levels that are unsafe.
Without a properly functioning TPR valve, water in the water heater may exceed the boiling point 
and become superheated. Once superheated water comes in contact with the atmosphere, it will instantly turn into steam resulting in a huge explosion. This explosion can propel the water heater through multiple floors, damaging property and causing personal injury.
The TPR valve should be connected to a discharge pipe that extends to the floor. The discharge pipe helps prevent occupants from being burned if the valve is activated. An activated TPR valve will eject a powerful jet of hot water so it important to route the hot water to an adequate discharge location.
Discharge Pipe Requirements
Discharge pipes connected to the TPR valve should meet the following requirements. Discharge pipes should:
- be constructed of approved materials including CPVC, copper, polyethylene, galvanized steel, polypropylene, or stainless steel. PVC should not be used since it can easily melt.
- not be smaller than the diameter of the valve it serves.
- not reduce in size as it extends down. This can result in an increase in pressure as water discharges.
- be as straight as possible.
- be installed in a way that allows it to drain by the flow of gravity.
- discharge into a floor drain, waste receptor, or the exterior.
- should not be trapped.
- not be connected to the drainage system.
- discharge through a visible air gap in the same room as the water heater.
- not terminate more than 6 inches above the floor or waste receptor.
- discharge in a way that prevents scalding and does not cause structural or property damage.
- discharge to a termination point that is readily observable by occupants. Discharge indicates that there is something wrong and the unit should be further evaluated by a plumber.
- not have valves, fittings, or threaded connections at the end of the pipe.
Leaks
If water leaks are seen coming from the discharge pipe, the TPR valve may be failing and should be replaced. In the event the TPR valve activates, homeowner’s should immediately shut off the water and contact a licensed plumber for repair.
For more information about TPR valves, or to schedule an inspection, call us at 813-261-0002 or visit our website at https://homecheckfl.com.