Pressure relief valve extension

The pressure relief valve extension is plastic and has a couple of elbows leading it to a drain. I always advise the client that the pipe should be copper and should terminate about 6" inches from the floor. I explain that it was routed to a drain to prevent a mess if it discharges but that you would want to see water on the floor if it was dripping or pressure had blown off so that you know there is a problem. I come across this A LOT around here and always write it up that it is not a preferred installation but want to ask what others thought. Thanks!

When I find a PTR valve extension piped improperly, I simply note it and leave it at that.

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.
  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 an indirect waste receptor or to the outdoors. Where discharging to the outdoors in areas subject to freezing, discharge piping shall be first piped to an indirect waste receptor through an air gap located in a conditioned area.
  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. 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 A112.4.1.

What’s up with the water heater roller coaster vent? I’d be writing up that vent installation.

All the Plumber had to do was install a WYE insert (at the main) and install the vent tubing into that.

Lousy install on the gas line fittings also. I wouldn’t write it up but they didn’t need two elbows and a TEE. It could have been done with one elbow with a twist of the TEE.

From the 2006 IRC.

  • P2803.6.1 Requirements for discharge pipe. The discharge piping serving a pressure-relief valve, temperature-relief valve or combination valve shall:
      1. 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.

TABLE P2904.5
MATERIAL ------------------------------------------------ STANDARD
Brass pipe ------------------------------------------------ ASTM B 43
Chlorinated polyvinyl chloride (CPVC) plastic pipe and tubing - ASTM D 2846; ASTM F 441; ASTM F 442; CSA B137.6
Copper or copper-alloy pipe -------------------------------- ASTM B 42; ASTM B 302
Copper or copper-alloy tubing (Type K, WK, L, WL, M or WM) – ASTM B 75; ASTM B 88; ASTM B 251; ASTM B 447
Cross-linked polyethylene (PEX) plastic tubing ---------------- ASTM F 877; CSA B137.5
Cross-linked polyethylene/aluminum/cross-linked polyethylene (PEX-AL-PEX) pipe - ASTM F 1281; CSACAN/CSA-B137.10
Cross-linked polyethylene/aluminum/high-density polyethylene (PEX-AL-HDPE) - ASTM F 1986
Galvanized steel pipe ---------------------------------------- ASTM A 53
Polybutylene (PB) plastic pipe and tubing --------------------- ASTM D 3309; CSA CAN3-B137.8
Polyethylene/aluminum/polyethylene (PE-AL-PE) composite pipe - ASTM F 1282
Polypropylene (PP) plastic pipe or tubing ----------------------- ASTM F 2389; CSA B137.11
Stainless steel (Type 304/304L) pipe -------------------------- ASTM A 312; ASTM A 778
Stainless steel (Type 316/316L) pipe -------------------------- ASTM A 312; ASTM A 778

Code is nice…but remember…it is the lowest possible standard. For instance, look at the temperature that the TPR valve releases at…then look at the 180 degree tolerance of the CPVC tube.

The author of this thread advises his clients to use copper. Personally, I consider that good advice. While the lowest possible standard might allow something else…he is probably setting his and his client’s standards for safety a tad or so higher.


I would agree with you if the CPVC was under pressure but it is not in this case.

Copper if fine, CPVC is fine unless the manufacturer states otherwise.

I agree David and it’s already written up. Thanks again!

Thanks for taking the time to list the requirements. It’s certainly a help and a good reminder!