How To Protect PEX Pipe From UV Light (Here Are the Details)

Sean Jarvis
by Sean Jarvis
PEX pipes are some of the most durable, useful, and versatile construction materials, but they are easily damaged by UV lighting. The heat that UV lights put off can damage PEX pipes, but you can protect them in several ways including latex paint. Whether it be location, storage, or installation, let’s take a look at how you can protect PEX pipes from UV lighting.

Copper pipe has been the go-to for plumbing because of its many great qualities. Then about 25 years ago PEX pipe started to become more popular in the US, thanks to its ability to withstand pressures and temperature changes in domestic hot and cold systems.

To protect your PEX pipe from UV light, you need to shield it with a UV-blocking material. You can do this by purchasing a pre-sheathed pipe from a manufacturer. Or, if you already have the PEX pipe, you can coat it with a layer of latex paint to protect it from the UV rays.

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What is PEX Pipe?

PEX is a flexible tubing that comes in long rolls and has several advantages over more traditional piping.

You can use it for long, continuous runs through your house, thanks to its ability to bend without needing elbows and joints. This means that you can easily work it through joists and studs and around corners without needed to take the time to weld or glue on extra pieces.

PEX doesn’t sweat under high humidity conditions, nor does it burst even when water lines freeze solid. This flexibility offers a wide array of uses and makes it great for very cold climates.

If you need to add joints to the PEX pipe, you connect these fittings by crimping metal rings over the barbed fittings. These metal rings are smaller and cheaper and eliminate the need to buy specifically sized parts for other types of piping.

Why Does UV Light Cause PEX to Degrade?

When PEX piping is exposed to UV light, it consumes the chlorine-inhibiting antioxidants which protect the pipe. As they get consumed, PEX pipe is left vulnerable to degradation thanks to the chlorine in the water.

UV light itself isn’t the sole reason for failures in PEX piping. What sunlight and fluorescent lighting does is speed up the damage caused by chlorine in the water. This damage still would have occurred but over a much longer time period.

It isn’t only UV rays from the sun that cause a speeding up of degradation. Fluorescent lights happen to be the main cause, as most PEX piping is installed indoors.

A study found that 8 hours of exposure from a fluorescent light is equal to one minute of sun exposure. This is why many PEX manufacturers installation instructions state “Do not install.. within 5 ft of direct view from fluorescent and LED lighting without protection.”

Signs that your PEX piping is degrading are ‘popcorning’ of the pipe surface. This is noticed by white lines along the PEX pipe that look like small scratches.

This is the reason that PEX suppliers and plumbers must store PEX pipe away from sunlight before installation. Sunlight not only aids in degradation but will also experience loss of flexibility and elasticity.

Protecting PEX Piping

PEX will contract and expand depending on the temperature. This helps it not burst when the water inside freezes, though it causes the pipes to move back and forth and will need to be protected against abrasive surfaces.

Keep your PEX piping away from hot appliances, such as the water heater. Common building codes require PEX to be at least 18 inches away from water heaters to protect the plastic piping from melting.

It’s important to protect your PEX with pipe insulation, abrasion clips, or enclosed in a larger pipe. This will stop any friction from happening which, over the years, can cause holes in the PEX.

If your pipe is enclosed in concrete or running through wood studs and joists, use an abrasion clip or suspension clip. Pay attention to places where the pipe bends in areas it passes through and protect these sections of PEX.

Using PEX Piping

Deciding on whether or not to use PEX pipe depends on a number of factors.

What will the application be?

  • Domestic potable hot and cold water?
  • Heating systems?

What kind of liquid will be carried by the PEX pipes?

  • Clean, soft water?
  • Hard, acidic water?
  • Chlorinated water?

Where will the system be located?

  • Hidden behind walls?
  • Inside a structure, but not in a heated area?
  • Underground?

In order to determine if PEX piping is the best solution for you, over copper, steel, and CPVC, you need to consider all of these aspects in regard to your piping system.

One thing that stands above all others if you decide to move forward with PEX pipes, is to make sure that the PEX manufacturer follows the plumbing codes necessary for safe transport of liquids.

In the U.S., that means PEX piping that is tested and rated to NSF/ANSI 61 by ASTM International. This will help you determine which system will work best for you.

If you are unsure, contact a licensed plumber who has experience with PEX piping.

Connecting PEX Piping and Joints

What sets PEX piping apart from others is the barbed fitting/crimping ring combination. This eliminates the need for solder, glue, or pipe wrenches. The only tools you need is a PEX Cutter and the Cinch Clamp.

To connect PEX fittings you can use Stab-In fittings or Cinch Clamps.

Stab-In Fittings are used when you have access to the joint. They don’t require any special tools, you just push the PEX pipe into the openings and press the outer ring into onto the fitting to tighter the connection.

With Cinch Clamps, you need a cinch clamp tool, which will tighten the clamp. The clamps come in different widths and you adjust the tension with the clamp tool, allowing it to fit many sizes of PEX tubing.

Adding PEX to an Existing System

If you are adding PEX to an existing system that has other types of pipes, there are a number of different fittings that will attach the PEX to them.

Purchase the special transition fitting needed to connect your existing copper, CPVC or steel pipes to the PEX. You will need to solder, glue, or thread on the fitting, then push the other end into the PEX pipe and put a crimp clamp around it to hold it into place.

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Related Questions

Can I Mix and Match PEX Piping and Parts from Different Manufacturers?

While there are several different manufacturers of PEX, you run the risk of voiding your warranty or failing inspection if you do not use parts from the same source.Because there is so much variety within PEX piping, you should always use the products from the same source to safeguard against leaks and water damage.

My PEX Pipe Has a Kink, What Now?

If you find a kink in your PEX line, you can repair this temporarily with a heat gun but the PEX tends to re-kink in the same spot. If you don’t want to cut the kink out because it is in the middle of a long, straight run.  Use a heat gun to and then cover the area with a hanger or abrasion clip.

Is PEX Safe to Use for Drinking Water?

There have been numerous studies to show that there are no health risks associated with drinking water from a PEX piping system. Though a few types of PEX-pipe may cause prolonged undesirable taste and odor if the water remains in pipes over time, there are no adverse health effects associated with this.

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Sean Jarvis
Sean Jarvis

Sean Jarvis is an interior decorator, writer, and expert handyman. Well versed in everything home improvement, he is a savant at manipulating words and spaces and upgrading everything around him. Sean specializes in writing concise guides about appliance repair and installation, home and lifestyle, and other residential projects.

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