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Water Heater T & P Valve Drain Line

504.6 # 6.....6. Discharge in a manner that does not cause personal

injury or structural damage.

If you use PEX (flexible) then it would be possible for the pressure relief valve to cause personal injury if not secured.

Still looking about the rigid stuff............
 
* * * *

Agree on Item #6, from Section 504.6 [ `06 IPC ], ...unfortunately,

in most cases, the plumber that did the install is not around to incurr

those [ possible ] personal injuries, and most homeowners and a lot

of inspectors are not aware of the fastening requirements and the

amount of potential damage / injury that is possible with a fully

discharging T & P valve line.

In days gone by, it used to be common practice to install a 3/4"

copper [ rigid ] drain line on the T & P valves.

& & & &
 
1) In years past the plumbing code said all pipe sizes are inside diameter (I.D.)

2) 3/4 pipe is 3/4 pipe regardless of the material

3) Refer to strapping requirements from Chapter 3 (pex every 32") small screw in water heater jacket

Burn your energy on Chapters 4, 7, and 9

Just my thoughts.............
 
skipharper said:
1) In years past the plumbing code said all pipe sizes are inside diameter (I.D.)2) 3/4 pipe is 3/4 pipe regardless of the material

3) Refer to strapping requirements from Chapter 3 (pex every 32") small screw in water heater jacket

Burn your energy on Chapters 4, 7, and 9

Just my thoughts.............
Click to expand...
Skip,

By reading this is it my understanding that you allow PEX to be used on T&P drains?

It would be interesting to see how many others allow PEX.
 
Based on the water distribution table and the fact that my staff only enforces the language of the code (no what if's allowed) leaves no choice.
 
& & & &

Mule,

Our AHJ allows pex also, but we require the minimum inside diameter to

be at least 3/4"......That typically means that 1" sized pex, with the

"inserted type" of fitings to be installed.....As Skip has stated, pex is

allowed by the IPC code.

& & & &
 
Last edited by a moderator:
We allow it also. However there are jurisdictions around ours that do not.

We allow the 3/4" pex because somewhere I remember something about the fitting being "nominal" sized. Which inmy opinion if it is a 3/4 fitting then it's 3/4".

Also ..... which don't make any sense .... the opening for the actual valve on the inside is only about a 1/4" in diameter. So why would a fitting smaller than 3/4" make any difference? Volume?

Also for some reason I seem to remember something about pex not being allowed within 18" of the valve because of ????????? Or am I having flashbacks of the 70's?

Skip, A screw in the jacket? Would that void the manufactuers warranty? Just throwing out some thoughts.
 
They say if you remember the 70's you weren't there!!! I do not believe the screw (small naturally) is an issue. I wonder how many folks require a 1" pex to a 3/4" hose bibb? I think the coke used to say nominal Mule however at 56, I have many strange flashbacks!!!
 
Don't have the code section handy, but in the '09 UPC, pex is not allowed to be installed within 18" of the water heater.

Therefore, I do not approve pex as a T&P line, or as a direct connection for the water supply or output.

Has anyone ever checked the listing of the pex in this regard?
 
From a pex website. http://www.ppfahome.org/pex/faqpex.html

What are temperature limitations for PEX?

PEX tubing can be used up to 200° Fahrenheit for heating applications. For plumbing, PEX is limited to 180° F. Temperature limitations are always noted on the print line of the PEX tubing.. PEX systems are tested to and can be used with standard T and P relief valves that operate at 210” F and 150 psi.

To me this doesn't make sense. PEX is limited to 180° F but can be used with standard T&P that operate at 210°. They do indicate that it HAS been tested though....
 
& & & &

Glennman ( and others ),



Wonder why the IPC allows it and the UPC does not? :confused:

& & & &
 
To me this doesn't make sense. PEX is limited to 180° F but can be used with standard T&P that operate at 210°. They do indicate that it HAS been tested though....
Click to expand...
The 180 degrees would be sustained use. When a T&P goes off at 210 it will discharge the hot water/steam for a short period of time. A 3/4" water line will flow about 25 GPM's at 60 PSI. Therfore the pex would not be subject to high temps for prolong periods of time.

JFYI we do not allow it here based on the UPC as glenman pointed out
 
Good find North Star--the concern is with the B Vent from gas water heaters. I think this holds true with any plastic water distribution tubing for obvious reasons. The relief line is allowed to be pex per the instructions which match the plumbing code. The only issue left would be the pipe size which to me, if it's 3/4", its 3/4".
 
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Skip,

What is the actual inside diameter of 3/4" pex tubing / piping...

Also, what is the inside diameter of the "inserted type" fittings

installed inside of the 3/4" pex tubing / piping?

Has the "diameter of the valve" served been reduced by the

use of 3/4" pex.......Our forum friend "Mule" stated that he

thinks that that valve is 1/4" in dimension.

Your thoughts...

* * * *

 
While I have never measured these it is quite obvious to me that the inside diameter is smaller than 3/4". I simply use the rule of thumb that if you go into a supply house and ask for a pex male adapter in 3/4" thats what you will get. My personal opinion is if indeed the water heater relief line is blowing off due to pressure, and you use a 3/4 T & P with 3/4 pex x MIP adapter the intent of the code is met. In years past you could have seen a 1/2" sweat x 3/4" MIP adapter and that to me is what the code is trying to avoid. I do realize that in essance that is what has been created using pex however I lean on just reading the code book to my staff and do not add design thoughts, etc. to the code language. The books are already thick enough!!
 
The terms PEX pipe and PEX tube have been used interchangeably, however some manufacturers distinguish beween the two by manufacturing to different inside/outside diameters. For example, PEX pipe may be manufactured to IPS-ID (iron pipe size, inside diameter controlled) sizes with varying thickness to meet pressure requirements, while PEX tube may be manufactured to CTS-OD (copper tubing size, outside diameter controlled) sizes, commonly with a standard thickness of SDR-9 (standard dimension ratio).

What is the concern you have? The code allows copper or schedule 40 pipe which have different ID's which PEX uses the same national standard sizes.
 
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mtlogcabin,

If the question is being posed to me, my concern is that the

smaller sized pipe / tubing does not meet the letter or the

intent of Section 506.4, #3, `06 IPC.....That a "bottle neck"

[ if you will ] is created by installing a smaller diameter

piping......From the angry plumbers in this AHJ, they believe

that they are compliant by installing the 3/4" pex tubing with

the insertable type fittings......I would like to know which is

the compliant installation.

Glennman CBO,

From the WattsPEX web site, see Page 6: Water Heaters

and Boilers......This particular manufacturer requires the 18"

separation from water heaters.



http://media.wattswater.com/IS-WaterPEX.pdf



* * * *
 
north star said:
* * * *mtlogcabin,

If the question is being posed to me, my concern is that the

smaller sized pipe / tubing does not meet the letter or the

intent of Section 506.4, #3, `06 IPC.....That a "bottle neck"

[ if you will ] is created by installing a smaller diameter

piping......From the angry plumbers in this AHJ, they believe

that they are compliant by installing the 3/4" pex tubing with

the insertable type fittings......I would like to know which is

the compliant installation.

* * * *
Click to expand...
It would not be a smaller diameter under the code according to 506.4 #13

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.
 
* * * *

mtlogcabin,

Sorry, wrong code section listed.....Shoulda been Section 504.6, #3,

`06 IPC.

Skip,

So if a plumber installs a 3/4" Watts [ brand ] PEX, 3/4" tubing,

you would approve it as compliant, ...even though they require the

18" separation?

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