Pex A vs Pex B: The Ultimate Comparison

Last Updated On July 14, 2024

Updated on August 31, 2023



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PEX A vs. PEX B Know the difference

Wondering if you should choose PEX A or PEX B for your plumbing project? Curious how to identify the differences, and if it really matters? This article is for you!

Most homeowners have no clue which type of PEX to pick. Selecting the right type of PEX piping for your next home plumbing project isn’t as difficult as it might seem.

We used our plumbing expertise to put together this “PEX A vs Pex B Guide” – with the help of a licensed plumber, to give you a little help for your next PEX plumbing project.

Once you understand the differences – PEX A vs PEX B – and how to identify them…you’ll be able to make the easy choice for your plumbing project. 

What's In This Guide?

      How to Identify Pex A vs. Pex B

      The main distinction lies in the manufacturing process and resulting physical properties of these two common PEX pipe types. 

      Here is a quick way to identify the difference between the two PEX types if not labeled. 

      PEX A is more flexible, and will quickly return to its previous shape. PEX B can “crimp,” is more coil bound and is less flexible. 

      When you compare PEX tubing – PEX-A with PEX-B, some key differences emerge:

      PEX A, formed through the Engel method, is more flexible than its counterpart. This flexibility makes it easier to install around corners without needing elbow joints.

      In contrast, PEX-B pipe, created via Silane or moisture cure method, has a stiffer structure but boasts greater burst resistance due to its molecular makeup.

      Easily Identifiable Differences Between Other PEX Types

      • PEX-A has higher flexibility compared to other types which makes it easier to install around corners without needing elbow joints.
      • The ability of this type of piping system allows users to use expansion fittings which are more reliable than crimp rings found on PEX-B.

      Watch: Video Highlighting the practical differences between PEX A & B.

      What Do Real Users Say About PEX A vs. PEX B?

      Some real users in the field report PEX A being “more foolproof” than PEX B, meaning it’s easier to work with due to its flexibility. 

      PEX A is less likely to freeze if used in colder conditions, and can also handle higher water pressure up to 500 PSI. 

      That said, most plumbing professionals don’t make a distinction between the type of PEX pipes used. Users often don’t feel the differences are important enough to fuss over for most projects. 

      Pex A vs Pex B – Advantages & Disadvantages

      PEX piping has grown in popularity due to its flexible properties in new construction, its longevity, and low-cost advantages compared to copper pipes

      We have written extensively about PEX elsewhere. We cover common questions such as using it in freezing temps, how to cut it, and a few of its disadvantages.

      But you’re probably not here for that. 

      Not many people understand a PEX A and PEX B even exist, or how to identify the differences.

      Let’s get deeper into this…

      List of Pros and Cons of PEX-A

      The main distinction lies in how manufacturers form PEX-A. The process involves peroxide (also known as “Engel method“) to create strong cross-links between molecules during manufacturing.

      The Engel method is known as the PEX-A method because it produces PEX pipes with the highest degree of cross-linking (around 85%) and the highest flexibility among the three types of PEX (A, B, and C). 

      PEX-A pipes can be easily bent and reshaped using a heat gun, and they have better resistance to stress cracking and chlorine degradation than PEX-B or PEX-C pipes.

      This results in a flexible and resilient material that can withstand high temperatures and pressures without losing its shape – indeed, even when bent or stretched, the interior size doesn’t change.

      PEX-A is known for its flexibility, making installation easier compared to other forms. This makes it easier to work with, and install in tight spaces.

      PEX A has expansion and contraction properties. This allows the user to expand the end of the pipe with an expansion tool so that an expansion fitting can be inserted directly into the tubing itself without needing clamps or a crimp ring. 

      PEX A will shrink back down to its original size, forming a water tight fit over the connector. Depending on the temperature, this sealing process can take more time, but applying heat to the material will shorten the process.

      Pro Tip: PEX A can be joined using PEX B fittings, but PEX B can’t be joined using expansion fittings. 

      However, PEX A requires special tools which may not always be readily available and cost quite a bit more.

      Also, PEX A has less chlorine resistance than PEX-B, particularly with hot water. 

      Hot chlorinated water causes the material to break down over time which can lead to leaks. 

      So you might want to consider another material for those applications such as hot water hoses.

      Both type A and B leach chemicals into the drinking water. But type A has a much higher leach rate than PEX B. Both are approved for use in plumbing for drinking water.

      List of Pros and Cons of PEX-B

      PEX B is also cross-linked polyethylene but represents one of the most readily available to DIY’ers. It’s manufactured using a process known as the “Silane” or “Moisture Cure” method.

      The crosslinking occurs after the extrusion process by placing the tubing in a hot water bath or steam sauna. The degree of crosslinking for PEX-B is typically around 65 to 70%, which is not as evenly crosslinked as PEX-a tubing.

      This form of PEX stands out due to its high resistance to chlorine and excellent burst strength. These characteristics make it an ideal choice for residential water supply lines (though it will also degrade from hot chlorinated water, but at a much slower rate). 

      It has a lower cost than its counterpart. But when you add in the higher cost for fittings, the cost between the two becomes less important. 

      The greater savings is in the tools required. They cost much less and are more readily available.

      The main distinction in using them lies in how you join PEX tubing. PEX B doesn’t expand, so you need fittings that have a smaller opening, creating a flow restriction. 

      A crimp ring must be positioned correctly, or it will leak at the connection.

      When sizing for PEX-B, you should use a larger diameter pipe to compensate for the narrower fittings. For example, a typical ½-inch waterline pipe should upsize to ¾-inch.

      Also, more recently, a few PEX- B pipe manufacturers have offered expansion fittings.

      PEX-B lacks flexibility when compared with PEX-A. 

      This can make it more difficult to run it in tight spaces or where tight bends are needed. 

      And if it crimps, it won’t go back to its original shape. Once PEX-B kinks, you have to cut it and use a coupler to connect it.

      Pictured: PEX pipe being used for water supply lines to a sink.

      Pex A vs. Pex B – Wait, Back it up. What is Pex?

      In general, PEX stands for cross-linked polyethylene, a type of flexible plastic used extensively in modern plumbing systems. It has gained popularity in the building trades due to lower costs and ease of installation.

      PEX is an alternative to polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and copper tubing. Though its long-term viability has not yet been established.

      Final Thoughts On Pex A vs. Pex B

      Deciphering the puzzle of PEX A vs. PEX B isn’t as complex as it seems.

      Once you learn about their unique characteristics, uses, and how to identify them in your plumbing system, you’ll be in a better position to decide which PEX type is right for you.

      PEX A brings flexibility and resilience while PEX B offers cost-effectiveness and resistance to chlorine.

      The choice between the two often boils down to specific project requirements and personal preferences. However…

      It is advisable to use only one type of PEX throughout your entire building or project. Mixing PEX-A and PEX-B may cause headaches during future maintenance.

      If you need further assistance, Plumbing Navigator is here for all your plumbing needs!

      Remember: Knowledgeable decisions lead to smarter solutions!

      FAQs Related To Pex A vs. Pex B

      Do I want PEX A or PEX B? 

      The choice between these two depends on your specific needs. While both are reliable options, they have easily identifiable differences that may influence your decision.

      PEX A is more flexible but slightly costlier than its counterpart; whereas, PEX B offers excellent durability at a lower price point. If you need more flexibility, choose PEX A. 

      Do PEX A and PEX B use the same fittings?

      PEX A and PEX B use different fittings. PEX A pipe uses an expansion fitting that doesn’t reduce the opening size. PEX B pipe uses a fitting that will reduce the diameter and slow the flow of water.

      Does PEX A leach more than PEX B?

      No significant differences have been found in terms of leaching between the two types of PEX piping. Both meet safe drinking water standards when installed correctly.

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      About Plumbing Navigator

      We write about "all things plumbing," helping you navigate common questions, repairs, and the best plumbing products on the market.

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      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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