Non-metalic Water Heater Discharge Pipe?

3/12/2010

8 Comments

 
Q: Is cross-linked polyethylene (PEX) tubing an approved material for water heater pressure and temperature relief valve discharge piping?
8 Comments
Steve
3/12/2010 03:15:18 am

A: Yes, unless explicitly prohibited by the manufacturer of the PTRV or the PEX tubing. Section 504.6, Item 13, specifies that the piping must be of a material listed in Section 605.4, which references Table 605.4 (or conforms to ASME A112.4.1). PEX tubing is listed in Table 605.4 and therefore approved. The installation of the tubing must also comply with the other items in Section 504.6. For example, the tubing must be adequately anchored in place so it will discharge in a manner that does not cause personal injury, flow by gravity to the discharge location and not create a trap. In addition, Section 605.4 prescribes a minimum pressure rating of 100 psi at 180 degrees Fahrenheit for hot water distribution piping. Although the PTRV discharge piping is not hot water distribution piping, this provision typically is interpreted to apply to the discharge piping.

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Steve
3/12/2010 03:32:30 am

Note that the referenced sections are from the 2009 IPC. Corresponding requirements occur in 2009 IRC Section P2803.6.1.

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rick coffman link
3/12/2010 04:01:45 am

Can you reduce the drain size of a relief valve? I believe that all PEX fittings are insert fittings and will reduce the drain size so unless it is a listed relief vale tube PEX wouldn't be allowed.

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Mark
3/12/2010 04:04:15 am

Its difficult to get the tubing to hang straight down. I've only seen it two times, but would discourage it. It looks sloppy and unprofessional to have duct tape wrapped around a WH holding the tube in place.

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Ron
3/12/2010 05:40:34 am

Rick, how about using one inch PEX on a 3/4" valve? I don't think there is such a thing as a listed relief valve tube.

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rick coffman link
3/12/2010 05:59:37 am

Ron
They do make a listed relief valve tube, we use them in CF all the time, the max BTU rating is written on the tubing.
As far as using 1" PEX, if they had a 3/4 in nipple to a 1x3/4 in red coupling with a 1" PEX male adaptor in it I would look at it. The main thing is that if that relief valve goes to a full dump you don't have any restrictions!!
Rick

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air conditioning service and repairs link
2/17/2015 02:08:18 pm

Although the PTRV discharge piping is not hot water distribution piping, this provision typically is interpreted to apply to the discharge piping.

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