Final answer:
The discharge piping for a T/P relief valve must be installed 6 to 18 inches above the floor to prevent scalding injuries and comply with plumbing codes.
Step-by-step explanation:
The question refers to installation requirements for Temperature/Pressure (T/P) relief valves discharge piping in water heating systems. According to many plumbing codes, including the universally-adopted International Plumbing Code (IPC), the discharge pipe for a T/P relief valve should be installed so that it is between 6 to 18 inches above the floor. The aim of this requirement is to reduce the risk of scalding injuries, as the T/P relief valve will discharge hot water or steam if the temperature or pressure in the tank gets too high. The pipe should also be made of a material that can withstand the temperature of the discharge and should not be directly connected to a drainage system to prevent potential backflow into the potable water system.