Cross-linked polyethylene, widely known as PEX, is a type of plastic that is currently the preferred material of many industries over traditional galvanized steel and copper for water supply in new construction and renovation projects.
Let’s find out why.
A. What Is PEX?
PEX plays an integral role in a water supply system. It is known to offer more advantages compared to metal pipes, like lead, copper and iron, and rigid plastic pipes, like ABS, PVC, and CPVC.
PEX pipes are made from cross-linked high-density polyethylene or HDPE polymer. The crosslinking of HDPE makes bridges among each polyethylene molecule. The resulting material is more stable under extreme temperatures, chemical attacks, and better resistance to creep deformation. The HDPE polymer is melted and continually squeezed into the tube.
You may have noticed different colors of the pipes. However, these do not indicate the distinctions of each. The main purpose of these colors is to make it easy for installers to determine if the line is carrying hot water or cold.
- Red PEX pipes carry hot water.
- Blue PEX pipes carry cold water.
- White PEX pipes can either be used for cold or hot water.
- There are also gray PEX pipes that serve the same function as the white ones.
It comes in varying lengths. It can come in 10-ft. pieces for minor repairs and over 500-ft. long for residential water supply installation. PEX pipes range from ⅜ to an inch in diameter and their color coding make it easy to determine the function of a particular pipe.
B. Are There Different Types of PEX?
There are three types of PEX. They differ in what manufacturing process was used in making them. When buying PEX, you’ll notice labeling with either A, B, or C. Choose the pipe that will meet your requirements best.
PEX-A is made using peroxide. Among the three types, it is the most flexible. This makes it ideal for residential water supply lines. It can expand to an immense degree when exposed to freezing water. This means it has the highest resistance to cracking in extreme temperatures.
It’s simple to work with. However, it’s the most expensive among the types. Except for its flexibility, PEX-A has no other important advantage over PEX-B.
PEX-B is made through the use of a moisture-cure technique. It is a bit stiffer compared to type A. It has a specific “coil memory” that will make the pipes want to go back to their initial coiled state.
This memory, however, is not an issue when installing. This type is a common choice for home plumbing. It’s cheaper compared to type A and can also expand to withstand cracking in freezing water.
PEX-B is also highly resistant to chlorine, making it suitable for areas that have highly-chlorinated water.
PEX-C is made through an irradiation procedure. It’s the most challenging to work with as it’s the stiffest among the three. Its stiffness makes this type most prone to kinking and cracking in freezing water.
These downsides make the type C most suitable for minor repairs and replacements wherein bending around the sharp corners is not needed. The good thing about this type is it’s the most affordable.
Here is an informative video that will give you more insights into the different types of PEX pipes.
C. What Are the Applications?
Due to its strength, flexibility, and resistance to harsh temperatures, PEX is ideal for the following applications:
- Hot and cold water plumbing systems
- Hydronic cooling and heating systems
- Service lines
- Residential fire sprinkler systems
- Snow melting utilization
- Outdoor lawn conditioning
- Permafrost protection under chilled warehouses
- Systems in ice rinks
D. What Are the Advantages?
PEX is known to possess a lot of advantages. Here are some of them below.
A main advantage of PEX is its flexibility. This allows PEX pipes to connect their ends to PEX manifolds, otherwise known as the main water control system. Then, they will wind through floors and walls to the individual fixtures without any interruptions.
Widely known as the “home run plumbing,” this setup uses one length of PEX for both cold and hot water supply fixtures in residential buildings. This will greatly reduce the risks of leaks in numerous connection sites.
PEX pipes don’t corrode, which is common in both steel and copper pipes. Corroded pipes will potentially lead to leaks and water contamination.
Since it is resistant to corrosion, there is no longer a need for protective layers and finishes. This will help save expenses.
PEX installation doesn’t require soldering.
Through PEX, water flows quietly. This prevents the “water hammer noise,” which is connected with metal pipes.
PEX can expand. This means it has high resistance to freeze-cracking compared to steel and copper.
Through the proper fittings, PEX pipes can connect to an existing metal supply line.
The color-coding makes it easier to identify the cold and hot water supply lines.
E. What Are the Disadvantages?
While PEX is a top choice for water supply lines, it still comes with it a few disadvantages.
Even though DIY installation is possible, special tools and connectors are still needed.
PEX is not ideal for outdoor use. Ultraviolet (UV) rays can lead PEX pipes to break down right away. Exposed pipelines could harden and will potentially crack in just a few months.
As for now, PEX is not recyclable as it can’t melt like the other recyclable types of plastic. The good news is since the demand for PEX is continually increasing, the effort to find a way for recycling it will surely increase.