Mar. 4, 2024

PEX-a vs. PEX-b: Choosing the Right Plumbing Solution 

by Alex Gross

In the realm of modern plumbing, two contenders stand out: PEX-a and PEX-b. Both are revolutionary advancements from the traditional copper and metal pipes of decades past. However, they differ in their composition, installation methods, and suitability for various applications. Let's delve deeper into the distinctions between PEX-a and PEX-b to help you make an informed decision for your next plumbing project.

What to know about PEX-a

PEX-a offers exceptional flexibility and resilience. The flexibility allows for the tightest bend radius to eliminate unnecessary fittings with each change in direction. Its elasticity allows for the use of larger-diameter expansion-style fittings, helping to ensure a secure connection. Additionally, in the rare instance of a kink, the thermal memory of PEX-a allows kink repairs with a simple shot of heat from a heat gun.

The benefits of PEX-a include a tight bend radius, thermal memory for easy kink repairs, and superior flow characteristics due to matching pipe and fitting diameters with expansion fittings. The only con is connections in cold climates. Expansion fittings may delay contraction to the original size, necessitating the use of a heat gun.

What to know about PEX-b

While PEX-b claims to be approved for use with expansion fittings, the pipe does not have the same elasticity as PEX-a and can therefore experience microcracks when expanding. Hence, PEX-b typically works best with smaller-diameter insert-style fittings that are secured by a crimp tool. The downside with insert crimp fittings is the restricted flow and lower system performance.

The limited flexibility of PEX-b (in comparison to PEX-a) makes repairs challenging in the case of kinks. PEX-b cannot be kink-repaired, so a coupling must be installed. This can pose issues if the installation is in a slab because some jurisdictions do not allow connections within a slab.

While both PEX-a and PEX-b exhibit resistance to corrosion, pitting, and scale buildup, there are notable benefits to PEX-a in relation to system performance and reliability. For example, the elasticity of PEX-a makes it more resilient in climates where freezing can occur. While no pipe is completely freeze-proof, PEX-a offers exceptional resiliency in freeze/thaw cycles.

Whether you opt for PEX-a or PEX-b, both alternatives offer advantages over traditional rigid piping materials, such as copper and CPVC. As the plumbing industry continues to evolve, innovations and applications for PEX will grow, reaffirming its position as a versatile and reliable solution for modern plumbing applications.