You gotta know your local code. GA uses the IPC, and regularly changes the discharge piping section to read like this: 504.6 Requirements for discharge piping. The relief valve shall discharge full size, separately to a safe place of disposal such as a concrete floor, outside the building, an indirect waste receptor, or other approved location. The discharge shall terminate in a manner that does not cause injury to occupants in the immediate area or structural damage to the building. When the relief valve discharge piping goes upward, a thermal expansion control device shall be installed on the cold water distribution or service pipe in accordance with Section 607.3.2. If the discharge pipe is trapped, provisions shall be made to drain the low point of the trapped portion of the discharge pipe. (Effective January 1, 2007) Even with our lax code, that install needs fixin'.