TPR material?

Is this corrugated pipe combined with the pvc ok?


I would say that is too many fittings, too many bends, too many restrictions.

Where does it discharge? Is that a garage? If so, it should go to the floor. Technically, the discharge point should be in the same room as the water heater (going through the wall is a code violation).

Except under the UPC.

PVC is not allowed, but that looks to be CPCV, which is allowed.

I’ve argued about the flex lines with a few AHJ’s. I don’t like them, but technically they’re allowed as long as they have a continuous downhill slope and no tight bends.

I would agree with Joe, however, nowhere is it written how many fittings or bends are allowed on the discharge pipe, but then common sense should prevail.

Here is food for thought… the corrugations reduce the “full size” opening of the discharge pipe. In that case, it would not be allowed in my opinion.


If used or allowed for water supply it is allowed for TPR drain pipe.

Local codes may be different.

I do not like lack of support or going through a wall myself.

Here are the exact codes.(Chicago )

18-29-504.7.1 Discharge.

The discharge from the relief valve shall be piped separately to an indirect waste receptor located inside the building. The discharge shall be piped full size and installed in a manner that does not cause personal injury or property damage and that is readily observable by the building occupants. The discharge from a relief valve shall not be trapped. The diameter of the discharge piping shall not be less than the diameter of the relief valve outlet. The discharge pipe shall be installed so as to drain by gravity flow and shall terminate atmospherically not more than 6 inches (150 mm) above the floor. The end of the discharge pipe shall not be threaded.

18-29-504.8 Required pan.

Water heaters or hot water storage tanks installed in locations where leakage of the tanks or connections will cause damage shall be installed in a galvanized steel or other metal pan of equal corrosion resistance having a minimum thickness of 24 gauge, 0.0276 inch (0.70 mm) Any water heater installed in a cabinet below a counter shall be provided with a drain pan.

But it’s flexible, and could whip around during release, possibly causing damage to the ©PVC piping, and potentially harming the occupants!!! :twisted:


Those two sentences state that the pictured material is not acceptable. The flexible pipe is smaller diameter than the relief valve outlet

I agree, and that was my position as well. However, I have been trumped by local officials.

95% of the homes in this area discharge through the wall. Must be a location thing.

OK, little editing to my post…
Nowhere, in the IRC is it mentioned how many fittings or bends are allowed on the discharge pipe.
However, the TRP Valve manufacturers will often times have their own rules and will say the discharge pipe shouldn’t be more than 30’ and should not have more than 4 elbows as this could cause restrictions and reduce discharge capacity of the TPR.
Here is an example:
Page 1 under Installation.

Haven’t we all :slight_smile:

2009 IRC P2803.6.1 Requirements for discharge pipe. The discharge
piping serving a pressure-relief valve, temperature relief valve
or combination valve 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.
  2. Not be smaller than the diameter of the outlet of the
    valve served and shall discharge full size to the air gap.
  3. Serve a single relief device and shall not connect to piping
    serving any other relief device or equipment.
  4. Discharge to the floor, to the pan serving the water
    heater or storage tank, to a waste receptor or to the outdoors.
  5. Discharge in a manner that does not cause personal
    injury or structural damage.
  6. Discharge to a termination point that is readily observable
    by the building occupants.
  7. Not be trapped.
  8. Be installed to flow by gravity.
  9. Not terminate more than 6 inches (152 mm) above the
    floor or waste receptor.
  10. Not have a threaded connection at the end of the piping.
  11. Not have valves or tee fittings.
  12. Be constructed of those materials listed in Section
    P2904.5 or materials tested, rated and approved for
    such use in accordance with ASME A112.4.1.

I Agree with what you are saying and there is a need for the rule to a point.

Pretty much std practice to pipe them through the wall in the greater Houston market, especially on new construction. Not arguing the IRC reference, but accepted by all AHJs that I know of here.