Can a TPR valve discharge to a water heater pan???

Specific Inspection Topics Plumbing Inspections
1

2009 IRC change highlighted below:

"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.
  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. **

  1. Discharge in a manner that does not cause personal
    injury or structural damage.
  2. Discharge to a termination point that is readily
    observable by the building occupants.
  3. Not be trapped.
  4. Be installed to flow by gravity.
  5. Not terminate more than 6 inches (152 mm) above
    the floor or waste receptor.
  6. Not have a threaded connection at the end of the piping.
  7. Not have valves or tee fittings.
  8. 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. 438"
2

Didn’t you answer your own question???

3

I think that was the point of the thread… It’s been discussed here several times, and the conclusion was that it couldn’t. Apparently now there is a change that allows it.

4

Okay, thought it was a strange question for Joe to be asking, but sometimes one never knows.

5

Prohibited in CA.

2010 CPC 508.5 Relief Valve Discharge. Discharge from a relief valve into a water heater pan shall be prohibited.

6

Dont really understand why they wouldnt allow the drain to dump into a pan. Its still going to a drain.

7

I think it’s a question of volume. If a TPR discharges it’s going to be under pressure. While the drain in the pan is likely the same size as the TPR discharge, it is only gravity fed. Therefore the pan will fill up and overflow.

In my opinion it really isn’t going to matter much one way or the other. If the TPR is dripping, the pan will be sufficient. If it’s discharging, it’s going to be splashing all over everything anyway, so the pan is going to likely be redundant.

8

Yes. I knew the answer. (Did you?) I was trying to be helpful.

9

**Exactly. **

Ben Gromicko even has a training package somewhere that say’s it’s prohibited because the pan doesn’t meet the definition of a waste receptor because the size of the drain pipe wouldn’t be able to accommodate a full discharge from the water heater. At least, that was the logic. I suppose the plumber and home builder’s lobby got it changed.

10

Here is an advanced question involving #4 of the 2009 code posted above…

  1. Serve a single relief device and shall not connect to
    piping serving any other relief device** or equipment**.

What if you see that the TPR is dumping into a larger pipe that also has the washer safety pan feeding into it at some other point?

The question is not about “will it handle the flow” but simply “does it meet the intent of the code”.

11

The plumber would not waste their time or money running it to the exterior if it could just be dumped in the overflow pan.