PEX Plumbing: Frequently Asked Questions

Written by Ashley Petersen 2017-01-19

PEX Plumbing

PEX is a flexible piping system used primarily for domestic water and radiant heating applications. The word "PEX" stands for cross-linked polyethylene. By a chemical or electron beam process, ties are created at the molecular level which improves the durability of the pipe. PEX was invented in the 1960's and has been used in Europe and the US for decades. Below are some frequently asked questions about the NIBCO® PEX flexible piping system.


Why is PEX a good product for plumbing?

NIBCO PEX is flexible, meaning it can make gentle curves behind the wall and thus reduce the number of joints. It also insulates better than copper meaning water noise is reduced. It is less conductive of heat and does not conduct electricity. No torches or solvent cements are used in its joining. NIBCO PEX is resistant to corrosive water and chemicals found in the plumbing environment. It is also freeze damage resistant. 

Does NIBCO offer a warranty on PEX?

NIBCO offers a 25 year system warranty on PEX when used as part of a NIBCO system. You can view details related to the limited warranty on page 38 of the NIBCO® PEX Piping Systems Catalog

Is NIBCO PEX safe for drinking water?

PEX is manufactured and tested according to stringent national consensus standards: ASTM F 876, F 877, AWWA C904 and CSA B137.5. NIBCO and independent third party testing agencies conduct routine quality control and quality assurance evaluations to ensure the product meets ASTM, ANSI/NSF International and CSA Standards. Compliance with the standards ensures the end user of safety and quality. Additionally, PEX is included in all of the major model plumbing codes used in the United States and Canada; NPC, UPC, IPC and NSPC, and approved by HUD for hot- and cold-potable water plumbing use.

Can PEX be used aboveground?

No. NIBCO PEX is tested for up to 6 months UV exposure, but this is only to provide protection during the installation phase. PEX should not be used outside because of UV exposure.

Can PEX be frozen?

NIBCO PEX is freeze-damage resistant. It should be treated like any other plumbing system - meaning it should be insulated against freezing. However, during power outages or other problems, if the tubing becomes frozen, in most cases it will expand to accommodate the frozen water and not leak when thawed.

How soon after installation can you pressure test NIBCO PEX?

Unlike some other PEX systems, NIBCO PEX can be tested immediately after installation is complete.

Can PEX be used in a hot water recirculation system?

Yes, NIBCO PEX can be used in a recirculating system. NIBCO recommends timed recirculation during demand periods as per the model energy codes. If the system must have continuous recirculating systems, use NIBCO PEX-b.

Can PEX be used under the slab?

Yes. The availability of long coil lengths means NIBCO PEX can be used under a slab without joints. PEX is not affected by concrete but should be sleeved for protection where it enters and exits the slab.

What are the temperature and pressure limitations for PEX?

PEX tubing is listed for operating conditions of 180°F at 100 psi. If the water is chlorinated like in almost all municipal water systems, these limits are 80 psi at 140° as per ASTM F2023 test conditions.

Can you use solvent cement to join NIBCO PEX?

No. PEX is joined with poly or metal insert fittings and crimp rings or sleeves using hand tools or power crimpers. 


Want to learn more about PEX plumbing? Check out this free and handy quick reference guide:
Download the Essential PEX Quick Reference Guide!

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