Copper crimping: One of the most common ways of connecting PEX is with copper crimping rings, which require the use of a special PEX crimping tool. The copper ring slips over the end of the PEX tube, and a fitting is then inserted into the tube. The copper ring is then pushed to the end of the tube—over the fitting—and a PEX crimping tool is used to crimp the copper ring (and tube) tightly in place.
Expansion connections: The expansion method of connecting PEX involves using a special PEX expander tool to stretch the diameter of the PEX tube before inserting the end of a fitting. The PEX tube then shrinks back to its original size to create a watertight seal around the fitting.
Stainless steel clamps (SSC): The SSC method of connecting PEX involves using a ratchet clamping tool to tighten stainless steel rings around PEX connections. Similar to the copper crimping method, the steel ring is slipped over the PEX tube before the fitting is inserted. The ratchet clamping tool is then used to squeeze a tab on the ring, which tightens the ring securely around the tube and the fitting.
Compression fittings: This type of radiant compression PEX fitting involves slipping a threaded brass nut over the end of the PEX tube, followed by a tapered plastic compression ring. A hollow brass tube is then inserted into the end of the PEX tube. The whole thing is then inserted into the end of a threaded fitting, and the threaded brass nut is then screwed onto the end of the fitting. As the nut is tightened, it squeezes the plastic compression ring against the end of the brass fitting to create a seal.
Push-fit connections: The quickest way to connect PEX is with the push-fit method, which involves purchasing special push-fit fittings that “grab” the end of the PEX pipe when inserted over the end. No special tools are required to use push-fit fittings, but a special removal ring is needed to remove them from the end of the pipe once you’ve connected it. This method is also one of the easiest ways to connect PEX pipe to copper for retrofit installations.
FAQs
Q. What is the difference between PEX-A and PEX-B?
The main difference between PEX-A and PEX-B is the manufacturing process. PEX-A is made using the peroxide method, during which cross-linking occurs at the same time as the extrusion process. When PEX-B is manufactured, cross-linking occurs after the extrusion process using a silane catalyst and moisture, which is why the manufacturing process for PEX-B is referred to as the silane method. Beyond the manufacturing process, PEX-A tends to be more flexible and has better kink resistance, while PEX-B is more rigid but has better resistance to chlorine, as well as a higher burst pressure.
Q. Is PEX safe for hot water?
PEX plumbing lines are safe for use in hot water applications and are widely used for residential hot water distribution, as well as hydronic radiant heating systems. However, it is not generally recommended to connect PEX directly to a water heater, especially gas or tankless models, as these appliances can reach high temperatures that may exceed the typical limit of PEX piping, which is usually up to 180 degrees Fahrenheit (82°C).
Q. Is PEX pipe safe for drinking water?
At one point, PEX piping was a questionable option for residential plumbing, but PEX pipes are now typically tested and certified to NSF/ANSI Standard 61, which is the official standard for drinking water system components. This certification and testing process ensures the pipes don’t release harmful chemicals into the water at levels that could put human health at risk.
Q. Is PEX pipe insulated?
PEX pipe does have some natural insulation properties since it has a lower thermal conductivity rating than copper or other metal pipes, but this minor amount of natural insulation does not negate the need for proper pipe insulation to prevent heat loss and freezing. It is recommended to insulate PEX pipes, especially in homes located in colder climates.
Q. Are PEX pipes safer than copper pipes?
While there are differences between PEX pipes and copper pipes, neither is definitively safer than the other. PEX pipes are more flexible and resistant to freezing, but they can break down when exposed to direct UV radiation. Copper has a high level of durability and won’t break down when exposed to the sun, but this material is more likely to corrode over time and may crack or burst in freezing conditions.
Q. How is PEX pipe different from PVC?
PEX pipe is a flexible material that is relatively easy to install and can be used in both hot and cold water distribution systems. PVC piping is rigid and relatively cheap, and has a high level of durability that makes it ideal for drain-waste-vent applications. Typically, PEX pipe is used to distribute incoming cold and hot water throughout the home, while PVC pipe is the go-to material for ventilation and drainage systems. Both materials are highly useful, but because of their differences, the general purpose for each does not usually overlap.
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The type and size of plumbing pipe chosen for any application depends on how the material will be used, the water pressure needs of the home, the drainage requirements, the specific appliance or fixture, and the preference of the homeowner or installer. For instance, PVC and ABS pipes are preferred for drainage and waste systems, while copper, CPVC, and PEX are commonly used for hot and cold water lines, with PEX being a popular option for DIYers who are not comfortable using a blowtorch or soldering.
Cross-linked polyethylene (PEX) is a type of flexible plumbing pipe made out of plastic that makes for a great alternative to copper or galvanized steel. You’ve probably seen rolls of blue and red PEX water piping in the plumbing aisle of your local home improvement store, but you might still be wondering exactly what is PEX piping and what is PEX made of. Continue reading this guide to PEX pipe to better understand what PEX pipe is, how it can be used, and why it’s a good choice for DIYers.
What is PEX pipe?
In 1968, German scientist Thomas Engel discovered a way to cross-link common plastic (polyethylene) through radiation to produce a much suppler form of the material. The new plastic, fashioned into flexible PEX pipe (also known as PEX tubing), arrived in the U.S. in the 1980s, initially for radiant floor heating systems. Today, PEX is used in more than 60 percent of new construction residential water supply systems.
Despite the popularity of the product, what is PEX tubing is still a common question, especially for DIYers who may not have a lot of plumbing experience. In essence, PEX tubing is a type of flexible plastic plumbing pipe used for hot and cold water lines as a substitute for copper.
There are several PEX pipe sizes, from ¼ inch to 2 inches, to accommodate a range of applications, and the flexibility of this product makes it an appealing option for retrofitting existing plumbing systems. However, it should be noted that PEX is vulnerable to UV radiation, so it must be stored and installed indoors and away from sunny windows to prevent premature degradation.
When to Use PEX Pipe
Photo: Elena Popova via Getty Images
PEX has a distinct advantage over copper and galvanized steel plumbing because of its flexibility, which allows one end of PEX pipe to connect to a PEX manifold (the main water control system) and then wind through walls and floors—uninterrupted—all the way to an individual fixture.
PEX piping is also less susceptible to temperature changes, making it a good choice for homes that may be at risk of frozen pipes since the PEX will expand, rather than crack. PEX can be used for both hot and cold water lines, as well as connections to various water-using appliances and radiant heating applications. If you’re trying to compare PEX pipe to PVC, note that these materials are usually used for different purposes. While PEX is typically for incoming water lines, PVC is generally used for drain lines, so there is no real overlap in use.
Types of PEX Pipe
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The different types of PEX material are also important to consider when answering the question, “What is PEX plumbing?” The three types of PEX—PEX-A, PEX-B, and PEX-C—are classified not by PEX pipe pressure rating or PEX pipe specifications, but instead, by manufacturing method.
PEX-A is manufactured using peroxide. It’s the most flexible of the three types and is suitable for use in all home water-supply plumbing needs. It expands to the greatest degree when subjected to cold, so it’s the most resistant to cracking in frigid temperatures. It’s easy to work with, but more expensive than B or C. Other than flexibility, PEX-A has no significant benefit over PEX-B.
PEX-B is manufactured using a moisture-cure method. It is slightly stiffer than PEX-A and has a distinct coil “memory” that makes the tubing want to return to its original coiled state. The coil memory, however, is not a hurdle to installation, and PEX-B is often the tubing of choice for residential plumbing because, while it also expands to resist cracking when water freezes, it is less expensive than PEX-A. PEX-B also features an increased resistance to chlorine, making it a good choice in areas where water is highly chlorinated.
PEX-C is manufactured via an irradiation method. Because it’s the stiffest version, PEX-C is the most difficult to work with; this stiffness also makes it the most prone to kinking and susceptible to cracking when water freezes. These undesirable traits make PEX-C best suited for short repairs where bending around sharp corners isn’t necessary. PEX-C is the most economical choice.
PEX Particulars
PEX is available in a variety of lengths, from short 10-foot pieces for small repairs to rolls over 500 feet long, which are used for installing a home’s entire water supply system. On average, PEX pipe costs about $0.40 to $4 per linear foot, which is around the same cost as CPVC, which runs about $0.50 to $3 per linear foot. Both PEX and CPVC cost less than copper piping, which has an average cost of $2 to $12 per linear foot. PEX pipe ranges from 3/8 to 1 inch in diameter, and its color-coding makes it a snap to identify what a specific pipe is used for.
PEX Pipe Color
PEX Pipe Function
Red
Carries hot water
Blue
Carries cold water
White
Carries either hot or cold
Gray
Carries either hot or cold
Pros and Cons of PEX Pipe
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As with any home-building product, there are both pros and cons to consider before deciding if PEX piping is right for your project. Check out the benefits and drawbacks of PEX to determine if PEX is a good choice for your home.
Pros
Installing PEX does not require soldering, while installing copper and galvanized steel does.
PEX expands, making it more resistant to freeze-cracking than either copper or steel.
PEX does not corrode, which can happen with both copper and steel pipes, leading to leaks and contamination of the water supply.
Water flows silently through PEX, eliminating the “water hammer” noise associated with metal piping.
Color coding (red and blue) makes it simple to distinguish hot and cold supply lines.
PEX can be connected to existing metal supply lines with the correct fittings.
Cons
PEX is not suitable for outdoor use. Ultraviolet rays cause PEX to break down quickly; tubing left outdoors can harden and crack within a couple of months.
PEX is difficult to recycle, but no longer impossible, so it’s often better to repurpose PEX rather than recycle the material.
Though installation is DIY-friendly, working with PEX requires special connectors and tools. Find a list of the necessary tools and connectors below.
PEX piping is susceptible to rodent damage, so it’s important that any homes using PEX are free of rodents and other pests that may damage the piping.
PEX Tool and Supplies
Photo: Glenda Taylor for Bob Vila
To make watertight connections with PEX pipe, you’ll need the right tools, fittings, and connectors. The following five methods are used for making the connections in PEX plumbing.
Copper crimping: One of the most common ways of connecting PEX is with copper crimping rings, which require the use of a special PEX crimping tool. The copper ring slips over the end of the PEX tube, and a fitting is then inserted into the tube. The copper ring is then pushed to the end of the tube—over the fitting—and a PEX crimping tool is used to crimp the copper ring (and tube) tightly in place.
Expansion connections: The expansion method of connecting PEX involves using a special PEX expander tool to stretch the diameter of the PEX tube before inserting the end of a fitting. The PEX tube then shrinks back to its original size to create a watertight seal around the fitting.
Stainless steel clamps (SSC): The SSC method of connecting PEX involves using a ratchet clamping tool to tighten stainless steel rings around PEX connections. Similar to the copper crimping method, the steel ring is slipped over the PEX tube before the fitting is inserted. The ratchet clamping tool is then used to squeeze a tab on the ring, which tightens the ring securely around the tube and the fitting.
Compression fittings: This type of radiant compression PEX fitting involves slipping a threaded brass nut over the end of the PEX tube, followed by a tapered plastic compression ring. A hollow brass tube is then inserted into the end of the PEX tube. The whole thing is then inserted into the end of a threaded fitting, and the threaded brass nut is then screwed onto the end of the fitting. As the nut is tightened, it squeezes the plastic compression ring against the end of the brass fitting to create a seal.
Push-fit connections: The quickest way to connect PEX is with the push-fit method, which involves purchasing special push-fit fittings that “grab” the end of the PEX pipe when inserted over the end. No special tools are required to use push-fit fittings, but a special removal ring is needed to remove them from the end of the pipe once you’ve connected it. This method is also one of the easiest ways to connect PEX pipe to copper for retrofit installations.
FAQs
Q. What is the difference between PEX-A and PEX-B?
The main difference between PEX-A and PEX-B is the manufacturing process. PEX-A is made using the peroxide method, during which cross-linking occurs at the same time as the extrusion process. When PEX-B is manufactured, cross-linking occurs after the extrusion process using a silane catalyst and moisture, which is why the manufacturing process for PEX-B is referred to as the silane method. Beyond the manufacturing process, PEX-A tends to be more flexible and has better kink resistance, while PEX-B is more rigid but has better resistance to chlorine, as well as a higher burst pressure.
Q. Is PEX safe for hot water?
PEX plumbing lines are safe for use in hot water applications and are widely used for residential hot water distribution, as well as hydronic radiant heating systems. However, it is not generally recommended to connect PEX directly to a water heater, especially gas or tankless models, as these appliances can reach high temperatures that may exceed the typical limit of PEX piping, which is usually up to 180 degrees Fahrenheit (82°C).
Q. Is PEX pipe safe for drinking water?
At one point, PEX piping was a questionable option for residential plumbing, but PEX pipes are now typically tested and certified to NSF/ANSI Standard 61, which is the official standard for drinking water system components. This certification and testing process ensures the pipes don’t release harmful chemicals into the water at levels that could put human health at risk.
Q. Is PEX pipe insulated?
PEX pipe does have some natural insulation properties since it has a lower thermal conductivity rating than copper or other metal pipes, but this minor amount of natural insulation does not negate the need for proper pipe insulation to prevent heat loss and freezing. It is recommended to insulate PEX pipes, especially in homes located in colder climates.
Q. Are PEX pipes safer than copper pipes?
While there are differences between PEX pipes and copper pipes, neither is definitively safer than the other. PEX pipes are more flexible and resistant to freezing, but they can break down when exposed to direct UV radiation. Copper has a high level of durability and won’t break down when exposed to the sun, but this material is more likely to corrode over time and may crack or burst in freezing conditions.
Q. How is PEX pipe different from PVC?
PEX pipe is a flexible material that is relatively easy to install and can be used in both hot and cold water distribution systems. PVC piping is rigid and relatively cheap, and has a high level of durability that makes it ideal for drain-waste-vent applications. Typically, PEX pipe is used to distribute incoming cold and hot water throughout the home, while PVC pipe is the go-to material for ventilation and drainage systems. Both materials are highly useful, but because of their differences, the general purpose for each does not usually overlap.
All You Need to Care for Your Lawn & Garden
Keeping your grass green and your plants thriving doesn’t just take a green thumb—it starts with the right tools and supplies.
