Journeyman Plumber ExamPlumbing Code and RegulationsMedium
A plumber is inspecting a new commercial building's water distribution system. The local code requires that all water heaters be equipped with a temperature and pressure relief (T&P) valve. Which of the following statements accurately describes the proper termination of the T&P valve discharge pipe?
- AIt can be piped directly to the building's sanitary drainage system without an air gap.
- BIt must terminate no more than 6 inches from the floor, regardless of the receptor.
- CIt must terminate with an air gap of at least two pipe diameters above the flood level rim of the receptor.
- DIt must terminate outdoors, at least 12 inches from any building opening.
Show answer & explanationAnswer & explanation
Correct answer: C. It must terminate with an air gap of at least two pipe diameters above the flood level rim of the receptor.
The T&P relief valve discharge pipe must terminate with an air gap above the flood level rim of an approved receptor to prevent backflow into the potable water system and ensure visible discharge.
Why the other options are wrong
- A. Direct connection without an air gap is prohibited as it creates a cross-connection hazard.
- B. While some codes specify a maximum distance from the floor, the critical requirement is the air gap above the receptor's flood rim.
- D. Outdoor termination is an option in some codes, but it still requires proper termination (e.g., directed downward) and is not the sole requirement; indoor termination with an air gap is also common.
T&P Valve Discharge Pipe Termination
The required method for safely routing the discharge from a temperature and pressure relief valve to prevent damage, injury, and cross-contamination.
- Must terminate to an approved receptor (e.g., floor drain, indirect waste receptor).
- Requires an air gap to prevent backflow into the potable water system.
- Must not be trapped, reduced in size, or have valves installed in it.
Memory trick: Air Gap's the Key to Keep Water Free!