If you stay in this business long enough, you see a bit of everything. Notice the water heater’s T&P valve in the above photograph. The T&P valve discharges vertically upward. What’s wrong with that?
There are many specific code requirements (13 to be exact) for the discharge piping from water heater T&P valves (Ref: 2012 International Plumbing Code 504.6). This installation violates requirements 8 and 9, which are:
8. Not be trapped.
9. Be installed so as to flow by gravity.
Obviously, with this incorrect installation, the discharge cannot flow by gravity. Also, water can fill and remain in the discharge pipe. Over time, stagnant water in the discharge pipe can corrode it and cause it to fail.
The International Plumbing Code Section 504.6 contains 13 specific requirements for T&P relief valve discharge piping. Common violations beyond the upward discharge shown here include:
- Discharge piping that terminates in an unsafe location
- Incorrect pipe material for discharge piping
- Improper pipe diameter
- Missing air gap at discharge termination
- Discharge piping that is threaded on the outlet end
Each of these violations creates a potential safety hazard. When a T&P relief valve activates, scalding water or steam discharges through the pipe. Improper installation can direct that discharge toward occupants or into areas where it causes property damage.
This is just a reminder. During field inspections, check the discharge pipe to verify code compliance.
Suggest topics for future blog posts.