Hot water Tank Discharge Pipe

Hello all,
Is this discharge legit? It comes out of the TPR and immediately takes a 90 degree turn and wraps around the tank and runs horizontal for a few feet then dumps into a drain stack. I am not sure if there is anything wrong with NOT going directly to the floor. All help is greatly appreciated.

No, it is wrong.

I would write it up as improper iunstallation and the discharge pipe was too small of a diameter.

This is a good candidate for the WTF thread. :wink:


Thanks Kevin! I appreciate the quick reply.

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From the AO Smith Installation manual…
"The Discharge Line:
• *Shall not be smaller than the pipe size of the relief *
*valve or have any reducing coupling installed in the *
discharge line"


It’s wrong in several areas.

The discharge piping serving a pressure relief valve, temperature relief valve or combination thereof shall:

  1. Not be directly connected to the drainage system.
  2. Discharge through an air gap located in the same room as the water heater.
  3. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap .
  4. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
  5. Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.
  6. Discharge in a manner that does not cause personal injury or structural damage.
  7. Discharge to a termination point that is readily observable by the building occupants.
  8. Not be trapped.
  9. Be installed so as to flow by gravity.
  10. Terminate not more than 6 inches (152 mm) above and not less than two times the discharge pipe diameter above the floor or flood level rim of the waste receptor.
  11. Not have a threaded connection at the end of such piping.
  12. Not have valves or tee fittings.
  13. Be constructed of those materials listed in Section 605.4 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.

Thank you, William.

Thanks Neil, I appreciated the help.

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@dfiala Welcome

Just asking. Does your report program have arrows? Or, do you use the hand in report?


That ain’t no Thing



I use the finger pointer in my reports. This is so much easier than marking stuff in the software. If I see something on a second story window I stand back, extend my pointer and take the photo. It’s ready for the report with no edits. Occasionally I use the arrows in the software if I am in a tricky spot. I should add, I do not use the software in the field. I compile my reports back at the office. I don’t want to wait on software in the field.

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It’s also a health hazard direct cross-connection with the waste system (Neil’s item 1 above).

BTW the finger thingy is a good idea. Do they come with the middle finger extended? :rofl:


Speaking of…just can’t resist…From my favorite Girl Band… Katzenjammer - Ain't no thang Live HD - YouTube

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