The discharge piping serving a temperature relief valve, pressure relief valve, or combination of both shall have no valves, obstructions, or means of isolation and be provided with the following:
- Equal to the size of the valve outlet and shall discharge full size to the flood level of the area receiving the discharge and pointing down.
- Materials shall be rated at not less than the operating temperature of the system and approved for such use.
- Discharge pipe shall discharge independently by gravity through an air gap into the drainage system or outside of the building with the end of the pipe not exceeding 2 feet (610 mm) and not less than 6 inches (152 mm) above the ground and pointing downwards.
- Discharge in such a manner that does not cause personal injury or structural damage.
- No part of such discharge pipe shall be trapped or subject to freezing.
- The terminal end of the pipe shall not be threaded.
- Discharge from a relief valve into a water heater pan shall be prohibited.