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Pex A  Vs  Pex B Fittings : Everything You Need to Know

Over the years, PEX has been replacing cooper and other piping materials in residential plumbing and domestic piping. The main reason for this is the high durability of PEX, cheap installation costs and its flexibility. This means that every plumber or homeowner who likes handling their projects needs to know as much as they can about PEX.

The common PEX pipes in the market today are PEX-A and PEX-B pipes.  The two dominant brands have their unique features and differences that you need to know. Uponor is a popular manufacturer of PEX-A While Zurn manufactures PEX-B. The two piping’s have different joining methods hence require different fittings.

First things first; what is the Main difference between PEX-A and PEX-B fittings? Unfortunately there are no universal fittings to fit both PEX-A and PEX-B. PEX-A works perfectly with expansion fittings while PEX-B uses insert style fittings.

PEX-A Vs PEX-B Fittings

There are different fittings in the market today that are used to connect PEX pipes.

There are crimp fittings that are used to connect PEX pipes with crimping tools. The crimping tools are used to fasten the crimp rings on the pipes to create a leak proof connection.

There are press fittings that are similar to the crimp fittings. However the press fittings don’t use crimp rings. The press fittings are inserted in the PEX pipes and compressed to give a secure leak proof connection.

For piping’s that experience high levels of expansion and contractions, expansion fittings are recommended.


There are push fittings too that are easy to install as they can be pushed in the PEX pipes without special tools.

You will need to know the different properties of the PEX pipe you are using before determining the type of fitting to use.


When you look with your naked eye, you will see that both PEX A and PEX B are almost the same size. There are however distinct differences in their flow restriction.


Expansion fittings are recommended for PEX A connections. The expansion fittings are made with a larger diameter and they require an expansion tool to fit them. The expansion tool helps you to enlarge the pipe and its sleeve which allows you to slide in the fitting. Considering that PEX A is expandable, the process is very easy and soon after the material shrinks back to its original shape giving the connection a snugly tight connection around the fitting.


The expansion fitting does not cause flow restrictions since the fitting is the same diameter with the pipe. The expansion fitting works perfectly for tight spaces making it very practical in hard to reach spaces like a joist-bay.


When expanding in cold regions or during a cold season, the expanded sleeve may take more than normal time to shrink back to its original size. To remedy this, it is advisable to have a heat gun that you can use to speed up the process by warming up the fitting.


The most recommended fittings for PEX B is the insert style fittings. Once you have inserted the correct fitting into the pipe, you use a copper sleeve to fasten it in place with a crimp tool.


The joining is faster and easier compared to the expansion style.

You do not need to worry about the weather being hot or cold as it does not affect the connection.



The connections cause a flow resistance in the piping system due to the smaller diameter of the fittings. This can cause a decrease in the amount of water received by the fixtures in our household.

You need to be careful not to crimp crooked joints as this can easily cause a leak making this fittings hard to fit in tight spaces as the crimping tool is not square to the sleeve.


Final Words

When settling on the fittings you will use on your piping project, you will need to first consider the type of PEX pipes you are using.

Most Crimps, Press and Push to fit fittings will work perfectly with both PEX A and PEX B pipes. However the expansion fittings work only with the PEX A due to its ability to expand and contract.

Read More: Which is Better for PEX Crimp or Cinch?