Code Ref for TPR valve piping?

Hi again.

Does anyone have a UPC code reference for approved piping material for TPR valve piping? It is my understanding that PVC does not meet the minimum temperature requirements and that CPVC does. Quick glance netted nothing in the IRC.


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UPC 608.5 Relief valves located inside a building shall be provided with a drain, not smaller than the relief valve outlet, of galvanized steel, hard drawn copper piping and fittings, CPVC, or listed relief valve drain tube with fittings which will not reduce the internal bore of the pipe or tubing (straight lengths as opposed to coils) and shall extend from the valve to the outside of the building with the end of the pipe not more than two (2) feet (610 mm) nor less than six (6) inches (152 mm) above the ground or the flood level of the area receiving the discharge and pointing downward. Such drains may terminate at other approved locations. No part of such drain pipe shall be trapped or subject to freezing. The terminal end of the drain pipe shall not be threaded.

Don’t know the code but that line looks like it goes uphill. Would certainly call that out.

[/size][/FONT]IRC P2803.6.2 Relief valve drains. Relief valve drains shall comply with Section P2904.5 or ASME A112.4.1.

IRC P2904.5 Water-distribution pipe. Water-distribution piping within dwelling units shall conform to NSF 61 and shall conform to one of the standards listed in Table P2904.5. All hot-water-distribution pipe and tubing shall have a minimum pressure rating of 100 psi at 180°F (689 kPa at 82°C).

Here’s the IRC reference table

Thanks David & Jeff. Those quick code reference listings are helpful Jeff. I do have the book open and read those passages.

Something else I want to bring up. As IRC states in 2803.6.1 Relief valve drains. The discharge pipe shall be installed so as to drain by gravity flow and shall terminate atmospherically not more than 6" above the floor.

I often see installations where piping from TPR valve(usually 3/4" copper) has one or more 90 degree turns before heading upward towards the main floor (when in basement) A certain percentage of time there is no cleanout or “bleeder” valve and I call that out.

Now, if the code refs. state slope to drain and you’re in a location like a basement where this is not possible, this is where a Watts 210 valve must be used? I’m asking because the valve in the photo is a Watts 100XL.

Here is the reference table. . .

The Watts valve in your photo is a standard “temperature and pressure relief” valve. When the temp or pressure becomes excessive, the valve will relieve that pressure, as often as is necessary.

The Watts 210 is a gas shutoff valve and relies only on temperature, and must be manually reset once it has operated. A pressure relief valve is required to be used in combination with the Watts 210.

Hey Jeff,

Most of the building departments I deal with want a TPR valve drain line to terminate no more than 6" above grade and or the waste receptor. They do allow condensation drain lines to terminate from 6" to 24" above grade.

**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.

In the state of CA, unincorporated cities/townships fall under the authority/jurisdiction of the Building Standards Commission and the Division of the State Architect. In such cases, CPC 608.5 defines the requirements for the termination of the discharge piping - not more than two (2) feet (610 mm) nor less than six (6) inches (152 mm) above the ground.

Most areas I know of in CA, follow this code as part of the 2001 California Code of Regulations, Title 24.

Your reference is from the International Plumbing Code (IPC) which is part of the International Residential Code (IRC). I don’t know of any jurisdictions in CA that follow the “I” codes.

Is the OC following the I codes?

What do you say about an extension pipe coming off a tp valve on a hot water tank that you can not identify. I saw one today. PVC, but the labeling was scratched out or worn out. What is the actual language that you would use in your report?
In my report, I caused an uproar, because I recommended that since I could not determine that it was safe that the extension pipe on the tp valve be replaced.

I’m not sure I understand. You say you couldn’t identify it. Then you said it was PVC.

What labeling?

How was it unsafe?

P.S. Are you related to Nick?

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Hey Guys,
Here is an issue… I have been wrestling with. How about T and P discharge pipes that discharge “lateral” across with little or (no) slope then discharge downward… You will see these at the top of water heaters.

I think it is a major safety issue that a lot of licensed plumbers even overlook when installing water heaters and TP valves. Slope is required for the discharge pipe and quite often its not there!

Do you guys often encounter this???

As long as it is not plumbed up hill it is ok.

TPPRV Drain Piping Max of 4 90deg elbows & max 30ft
When the water heater is in a basement or below grade, it may not be possible to arrange for a gravity drain of the TPRV. A Watts 210 valve can be installed. The temperture-sensing bulb of the valve goes in the upper portion of the tank, and the gas piping runs through the valve. The Watts 210 shuts off the gas it the temperture is in excessive. In addition a seperate water pressure relif valve must be installed in the piping and must drain as shown

Not sure if this answers your question but I thought I’d give it a whirl as i get so many answers from here

Yes, I have seen that Code Check diagram… they are great references for code.

As for the “lateral” line… I think it could still pose a “possible” safety hazard especially if corrosion or mineral encrustation clogs the lateral line after extended time maybe years of dripping… the water could lead back to the valve and cause failure. I am not sure how much testing has been done. But liability could be an issue here…

Especially since the code states the T and P discharge line is “required” to have slope…

Hank - Screw the code. Read the PVC pipe - rated for up to 73 degrees.

UPC 608.5 states, must drain by gravity-not uphill or trapped, no kinks or restrictions in pipe

Thanks… then that answers that question… It would make it a lot easier on all of us if the Water Heater manufacturers installed the TP valve on the side of tank instead of on top for the discharge pipe. And ofcourse if plumbers watched for this as well…

Did an inspection today in which the TP pipe was made of cpvc and was labeled 100psi at 180F. I know this is ok for water distribution piping but is it ok for a t&p pipe. The t&p valve on the water heater said 150psi at 215F.