Tpr Discharge line is PEX

Just wanted to know is pex line acceptable for use as the tpr discharge line on a water heater.
My thought is no because it is flexable. What are your thoughts please.:shock:

Can it handle 200 degrees?

Check search we just did this one)

From the Plastic Pipe and Fittings Association (PPFA)

**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.

Thanks Shephen I figured the temp was ok just not sure if the hot water made the PEX line like a garden hose and would spray everywhere instead of down. And the fitting on the picture is reduced in size and on any other application you cannot reduce the size less than 3/4.

Per the IRC, any pipe approved for water distribution is approved for the TPR discharge, for the 14,000th time.


I must have told you a million times Joe, stop exaggerating. ;):cool:

Nice chart by the way, thanx.:smiley:

Is the inside diameter of the elbow the same as the inside diameter of the pex? If not I would think this would not be allowed.

Paul this is not in response to your post

The fitting goes inside of the pex line so it would be smaller. So if its inside diameter of the fitting meets the requirments than it would be ok but it does not seem that anyone here seems to know.
I understand the pipe is ok for the temp that is why it is installed in the house on the hot water side of the plumbing. But the graph, chart or diagram does not show if the pipe will flex under high pressure spraying everybody that is in its path and with the elbow fitting being smaller that will help to increase the steam and high pressure water as it is coming out and spraying. have you ever seen a fire hose under pressure out of control and it isn’t hot water. I under stand that the pex pipe is ok temp wise. But they dont show installation insturctions for the fly by night contractors that use what ever they have left over to save money. Ie In some timelines outlets were not grounded, wires were covered with cloth, afci were not heard of. Just because it states that pex is ok to be used with tpr discharge lines does not tell me that the set up is ok and proper or safe for that matter.

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Why would it not be in response to my post? If the elbow is a smaller diameter then it would not be correct…in my opinion.

Pex is ok if its rated for that purpose but should be continious to the exterior without restrictive fittings I would think.

Not to mention the connection methods

Did it terminate within 4-6" of the ground in a downward fashion? Did they put a pvc or copper elbow at the end?

No it had no fitting at the end and was tucked under the earthquake straps.

I think it is not allowed to exit the wall to the exterior. It specifically states it cannot be used in contact with sunlight on most of the pipe I have seen, and is always broken off where the contractor has used it anyway. I would think it must have a copper elbow on the end that extends inside the wall to prevent sunlight from coming incontact with the PEX.

You are mistaken. Please post a copy of some literature from a manufacturer of pex that says it should not be exposed to daylight.

There is nothing in the IRC that prohibits fittings. Can’t speak for the UBC, but it’s probably the same.

From Uponor, manufacturer of Wirsbo PEX.

Storage and Protection: Store materials protected from exposure to harmful environmental conditions and at temperature and humidity conditions recommended by the manufacturer.
Store PEX tubing in cartons or under cover to avoid dirt or foreign material from being introduced into the tubing.
Do not expose PEX tubing to direct sunlight for more than 30 days. If construction delays are encountered, provide cover to portions of tubing exposed to direct sunlight.

From Vanguard site.

Q - Can CANPEX™ tubing be used for outdoor applications?**

                A - No. PEX is designed for indoor and buried applications                      only and is not recommended for outdoor use. Short exposures                      to sunlight are permissible, not to exceed 30 - 60 days. When                      storing CANPEX™ tubing, it must be stored under cover, shielded                      from direct sunlight.

Thanks. Learn something new every day. But I’m not going to get bent out of shape for 3" of a dry pipe hanging out of a wall. If it deteriorates after 10 years, replacing it is part of the joys of home ownership, called maintenance.

Most, if not all of the builders up here would install it and then paint it the same color as the house / trim. That would take care of the issue.

I think we are dealing with nominal pipe diameters here. Also, the tubing is stretched over the fitting barb. IMO: the inner diameter of the fitting is not an issue.

I have yet to see PEX used on a TPR and do quite a few new homes. There must be a good reason, besides sunlight, they are not using it all the time. It is so much easier to install than any other material. Any of the TX guys seen it and if so which builder?