Thread: Crazy TPR pipe routing

I called out an installation with 9.... yes 9 - 90 degree bends in it. Plus it runs uphill and effectively has a P-trap within a couple of the 90s.

Apparently, the plumber is defending it and is going to be calling me. Can anyone cite a quick code section of the many that are wrong here. Or, is it just a manufactuer's specification thing?

I dug up some old threads and it seems the most according to the manufacturers has been 4.

Edit: Just remembered.... it also joins another pipe of the same size/type along its run out of the house.

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Originally Posted by Matt Fellman

I called out an installation with 9.... yes 9 - 90 degree bends in it. Plus it runs uphill and effectively has a P-trap within a couple of the 90s.

Apparently, the plumber is defending it and is going to be calling me. Can anyone cite a quick code section of the many that are wrong here. Or, is it just a manufactuer's specification thing?

"Or, is it just a manufactuer's specification thing?" Yep.

I looked it up in my code book (Oregon Specialty Code) and the trap is a problem... as is the upward routing according to the section (attached document). I guess the 9 - 90s are just generally a bad idea.

Originally Posted by Jerry Peck

"Or, is it just a manufactuer's specification thing?" Yep.

How is it "just" a manufacturer's specification thing when the IRC prohibits trapping?

2006 IRC P2803.6.1 Requirements for discharge pipe.
8. Not be trapped.
9. Be installed to flow by gravity.

Here is what the NC code says about relief valve piping. It looks like your insallation violates 2,8,9.


504.6 Requirements for discharge piping. 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 either on the floor into an indirect
waste receptor or outdoors.
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. Deleted.
6. Discharge in a manner that does not cause personal
injury or structural damage.

7. Discharge to a termination point that is observable by
the building occupants.
8. Not be trapped.
9. Be installed so as to flow by gravity.
10. Not terminate more than 6 inches (152 mm) above the
floor or 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 AI12.4.1.

I talked to the plumber today.... he says trapping is allowed as long as there is a hole drilled in the trap. I'm starting to feel like I'm in an episode of the twilight zone.....

Have the plumber put it in writing with his state license number and sign it.
Then turn him in to the state.

Originally Posted by James Duffin

Here is what the NC code says about relief valve piping. It looks like your insallation violates 2,8,9.

504.6 Requirements for discharge piping. 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 either on the floor into an indirect
waste receptor or outdoors.
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. Deleted.
6. Discharge in a manner that does not cause personal
injury or structural damage.

7. Discharge to a termination point that is observable by
the building occupants.

8. Not be trapped.
9. Be installed so as to flow by gravity.
10. Not terminate more than 6 inches (152 mm) above the
floor or 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 AI12.4.1.

Originally Posted by John Arnold

How is it "just" a manufacturer's specification thing when the IRC prohibits trapping?

2006 IRC P2803.6.1 Requirements for discharge pipe.
8. Not be trapped.
9. Be installed to flow by gravity.

I was referring to the 9 - 90 elbows.

The entire discharge line did not meet what the code calls for, trap or no trap, I did not feel I needed to post that entire code section because it was so bad - I figured that the 9 -90 elbows would be enough to correct it.

James posted a partial list of the IRC requirements, as amended (and deleted) by NC.