Replacing old water heater - T&P Release Pipe

[chriskthx]

I am looking to replace my old electric water heater. The existing pressure release valve piping goes into my wall which I assume terminates to a drainage pipe. Code requires that it discharges to 6" above the the ground in the same room.

Has anyone encountered this before, and if so, is it safe to just cut and cap off the copper piping that extends into the wall and leave?

https://imgur.com/a/rzof364

 

[voletl]

You located down south?

If so... your releif valve needs to be piped as such.

 

[chriskthx]

You located down south?

If so... your releif valve needs to be piped as such.

Yes, Florida.

 

[chriskthx]

Florida Residential Code:
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.

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 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 the piping.

12. Not have valves or tee fittings.

13. Be constructed of those materials listed in Section P2905.5 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.

 

[Rickyman]

Number five says it can be piped to the outdoors

 

[Jeff Handy]

Rule # 2 says it needs an air gap.

If he adds one, who knows if the remainder of the existing pipe will drain by gravity, or could handle high flow without backing up from the air gap?

 

[Jeff Handy]

Meanwhile, unless you are getting inspected, maybe just connect the new TPR drain the same way?

After verifying that the current drain line works well, and go locate the outlet and make sure its clean and clear and visible.

In my town, they charge a permit fee but rarely if ever inspect for heater installs, so really just a money maker tax.

 

[bartleyhs]

Number five says it can be piped to the outdoors View attachment 23634

Rickyman,
I am in Florida and just replaced my WH, so even though I’m not a plumber, I recently became educated on this part of the code and asked about this because it seemed to contradict itself since plumbing it to the outside would negate number 2. It was explained to me that that sentence that you circled is grouped with the other things that can happen AFTER the 6 inch air break. It can go onto the floor, in a pan, etc. or be piped outside. Mine has the 6” gap into a pan and then the pan is piped to the outside.

 

[Jeff Handy]

Plumbing it to the outside does not negate rule # 2.

Create an air gap, in that room, then plumb the drain to outside, must drain by gravity.

There is no six inch air break, there is a six inch or less distance required from the end of the discharge to the floor, or whatever is receiving the discharge.

 

[bartleyhs]

Plumbing it to the outside does not negate rule # 2.

Create an air gap, in that room, then plumb the drain to outside, must drain by gravity.

There is no six inch air break, there is a six inch or less distance required from the end of the discharge to the floor, or whatever is receiving the discharge.

Hi Jeff,
The 6” distance from from the discharge to the floor is what I was calling an air break (gap). Sorry if my terminology was wrong. The point is that gap has to happen before any drainage to the outside. If that wording in #5 meant the TPR could be extended to the outdoors without an air gap (which is how I thought Rickyman was interpreting it) it would negate (or contradict) #2 that says the air gap has to be inside the same room. My conclusion for the correct way to drain to the outside was just as you suggested. Air gap to the pan (or drain) then pan (or drain) flows by gravity to outside.
I was responding specifically to Rickyman’s post where he circles the part in #5 that makes it sound like it’s okay to run the TPR directly to the outdoors. Since this was a part of the code that I questioned when installing my heater and drain I thought I would clarify what I had learned. Based on your explanation I was correct, although I may have used the wrong wording, for which I apologize.

 

[Jeff Handy]

No need to apologize.

Very tricky wording in that code, as with most of them, grrrrr.....

They write them so that they can screw you no matter what you do, so it seems.

Meanwhile, will there be an inspection?

Did this job need a permit?

Just wondering.

I think the old TPR valve drain system makes sense mechanically, but I see the code side also, wanting to guarantee the over-pressure water has somewhere to safely go.

The air gap acts like a fuse, so if the gravity drain (which would likely be a bigger diameter than incoming) is pinched or blocked, the high pressure discharge can safely overflow from the air gap, and not send the heater rocketing out through the ceiling!
Or just going kaboom like a water bomb!

I have seen videos, it actually happens, haha!

 

[Jeff Handy]

Here is a good video.

 

[Diehard]

My interpretation is the air gap req't of #2 is applicable to #1.

#5 and # 10 clearly allow discharge to floor.

Many try to read more into it than it's actual intent. Some Inspectors included.

EDIT: One must look at each individual requirement and understand what's it's intent is.

In most cases it's prevention of contamination of the domestic water in the tank.

Then there's not to include anything in the discharge line that may negatively affect the or hamper the maximum potential discharge requirement of the P&T Relief valve.

Then there's personal safety against scalding when discharging.

Not be left with connections that can easily be altered.

 

[frodo]

YES

if you install another water heater and you pipe the T&P down to within 6'' of the floor then you can abandon
the piping going outside. if i were you. simply place a cap on the pipe. it does not have to be soldered
so the next guy can use the pipe if he wants to

 

[bartleyhs]

No need to apologize.

Very tricky wording in that code, as with most of them, grrrrr.....

They write them so that they can screw you no matter what you do, so it seemsI

Thanks Jeff,
I just found this in the UPC training manual.
801.2 Air Gap or Air Break Required.
Indirect waste piping shall discharge into the building drainage system through an air gap or air break as set forth in this code.

I thought I had heard it referred to as an air break, now I know I’m not crazy. Maybe it’s one of those things that is said differently depending on where you live in the country. I really try not to respond to posts since I’m no plumber (I read them because I learn so much from you guys), but since this was a section of code that is confusing to us non professionals, I thought I would explain what I had learned about it from a novice’s perspective. Sometimes I think it’s hard for you guys to explain it to the novice because it all makes so much sense to you, that you might not understand where or why we are getting confused by it if that makes sense.
Anyway, always appreciate your posts, you are one of the ones here that always gives good helpful advice.
Cheers

 

[bartleyhs]

Many try to read more into it than it's actual intent. Some Inspectors included.

This is the main thing I have had to learn while trying to decipher the codes. Many times they seem to contradict themselves, but this particular section of code is the one that taught me to separate the points from each other, because each is talking about something different. When it was explained to me as you said that 1&2 were one thing and 5 was something else, I had an aha moment that has helped when reading other parts of the code. I honestly think they make it confusing just to make sure professionals are the only ones who can understand it so we DIYers don’t even attempt it., which may be smart.

 

[Diehard]

There are formal interpretations available upon request of many of the codes. But as I recall, it typically comes with some sort of enrollment and/or cost. Commonly used by many engineering firms.

In fact as I recall they actually publish the questions and responses somewhere, for future reference.

Don't ask me for any details on the process. I've been retired too long now.

 

[frodo]

There is a difference in the terms air gap and air break

First image is an air break. the indirect drain 90 is turned down and is below the flood level

Second Image is a air gap, the indirect drain 90 is turned down and a 1'' minimum gap is between the bottom of the 90 and the flood level rim of the fixture.

So. To make this understandable in your situation. If you ran a pipe from the T&P on the floor to a floor drain
and turned into the FD. that would be a air break

If you ran a pipe from the T&P to the floor drain and it was elevated on a 2x4 or unistrut
when the 90 turned down and it is 1'' above the FD. That is a Air gap

 

[bartleyhs]

There is a difference in the terms air gap and air break

First image is an air break. the indirect drain 90 is turned down and is below the flood level

Second Image is a air gap, the indirect drain 90 is turned down and a 1'' minimum gap is between the bottom of the 90 and the flood level rim of the fixture.

So. To make this understandable in your situation. If you ran a pipe from the T&P on the floor to a floor drain
and turned into the FD. that would be a air break

If you ran a pipe from the T&P to the floor drain and it was elevated on a 2x4 or unistrut
when the 90 turned down and it is 1'' above the FD. That is a Air gap

Thanks Frodo, that makes sense (I always appreciate the visuals you provide)