If you are planning a plumbing renovation or installing a new radiant
heating system, you will inevitably face a choice between plastic piping
materials. While copper was once the standard, flexible plastic pipes have taken
over the market.
The two main contenders are PEX and PERT. While they look similar,
understanding the difference between PEX and PERT pipe is crucial for the
longevity and efficiency of your system.
This guide breaks down the molecular differences, cost implications, and
ideal use cases for both.
What is PEX Pipe?
PEX stands for Cross-linked Polyethylene. It has been the dominant player
in the flexible piping market in North America for decades.
The "X" stands for cross-linking. During manufacturing, the polymer chains
in the plastic are chemically or physically linked together. This creates a
dense, three-dimensional network that makes the pipe incredibly strong and
resistant to extreme temperatures and chemical attack.
There are three main types of PEX (A, B, and C), classified by how the
cross-linking is achieved, but they all share similar high-performance
characteristics.
Best for: Potable water lines, high-temperature heating, and freezing
climates.
What is PERT Pipe?
PERT stands for Polyethylene of Raised Temperature Resistance.
Unlike PEX, PERT is not cross-linked. Instead, it achieves its strength
through a unique molecular structure and the use of special additives that
stabilize the polyethylene. Because it does not require the cross-linking
process (which takes time and energy), it is often cheaper to manufacture.
PERT has been popular in Europe for many years and is rapidly gaining
traction in the US market, specifically for radiant floor heating.
Best for: Radiant floor heating, low-pressure plumbing, and green building
projects (it is recyclable).
The Core Differences: PEX vs. PERT
To choose the right material, you must look at how they perform under
stress. Here is the detailed breakdown of the difference between PEX and PERT
pipe.
1. Temperature and Pressure Ratings
This is the most significant technical difference.
PEX: Because of the cross-linking, PEX can withstand higher temperatures
and higher pressures simultaneously. It generally has a higher burst pressure
than PERT.
PERT: While "RT" stands for Raised Temperature, PERT generally has lower
maximum temperature ceilings compared to PEX. It performs excellently at
standard heating temperatures (up to 140°F - 160°F), but PEX is superior for
extreme heat (up to 180°F - 200°F).
2. Environmental Impact and Recyclability
If sustainability is a priority for your build, this is a key
differentiator.
PEX: Because it is cross-linked, the molecular structure is permanently
changed. PEX cannot be melted down and recycled into new pipe.
PERT: Since it is not cross-linked, PERT is fully recyclable. It can be
melted down and repurposed, making it a greener choice.
3. Flexibility and Kinking
PEX: Flexibility varies by type (PEX-A is very flexible; PEX-B is stiffer).
However, PEX has "memory," meaning it wants to return to its original shape.
PERT: Generally very flexible and easy to lay out. It is often softer than
PEX-B, making it easier for installers to bend around corners in radiant heat
grids.
4. Installation and Fittings
The good news is that the hardware is often interchangeable.
Most PERT pipe is approved for use with standard PEX fittings (crimp rings,
cinch clamps).
Note: Always check the manufacturer's specifications. While PEX fittings
usually fit PERT, expansion fittings (typically used with PEX-A) may not be
compatible with all PERT pipes.
Quick Comparison Table
For a quick scan, here is how the two materials stack up against each
other.
Which Should You Choose?
The decision ultimately depends on your specific application.
Choose PEX if:
You are plumbing a whole house for drinking water. PEX has a longer track
record in North America for potable water and higher resistance to chlorine.
You live in a freezing climate. PEX has incredible expansion capabilities,
making it less likely to burst if water freezes inside the pipe compared to
rigid pipes (though no pipe is freeze-proof).
You need high-temperature performance. If your hydronic system runs very
hot (baseboard heaters), PEX is the safer bet.
Choose PERT if:
You are installing radiant floor heating. This is the "sweet spot" for
PERT. Because radiant floors run at lower temperatures and pressures, PERT
handles the job perfectly at a lower cost.
You want an eco-friendly option. The ability to recycle scrap pipe is a
major benefit for green construction.
Budget is the main constraint. For large-scale radiant projects, the cost
savings of PERT over thousands of feet of pipe can be substantial.
Conclusion
Both PEX and PERT are excellent, durable, and corrosion-resistant
materials. The main difference between PEX and PERT pipe lies in the molecular
structure: PEX is cross-linked for maximum strength and heat resistance, while
PERT uses stabilizers for flexibility and recyclability.
For general plumbing and high-stress environments, PEX remains the gold
standard. For radiant heating and eco-conscious projects, PERT is the smart,
cost-effective alternative.
Frequently Asked Questions (FAQ)
Can I mix PEX and PERT pipe? Yes, in many cases you can connect them using
standard crimp or clamp fittings, provided the pipe sizes are the same (e.g.,
1/2 inch). However, never mix the pipes in a way that exceeds the temperature
rating of the PERT pipe.
Is PERT cheaper than PEX? Generally, yes. Because PERT does not undergo the
expensive cross-linking manufacturing process, it is usually less expensive per
foot than PEX.
Does PERT last as long as PEX? When used within its temperature and
pressure ratings, PERT has a predicted lifespan similar to PEX (typically 50+
years). However, PEX has a longer proven track record in the North American
market.
