Can I Use PEX for Shower Valve? The Complete Expert Guide

As a home renovation specialist, I‘ve installed dozens of shower valves over the years. While old-school copper pipes get the job done, I‘ve found PEX to be a far superior plumbing material in most cases. In this comprehensive guide, I‘ll draw on my experience to walk you through everything you need to know about using PEX for shower valves.

An Expert Overview of PEX Tubing

PEX (cross-linked polyethylene) pipe has been around since the 1960s, but only gained widespread usage in the 1980s once improved manufacturing processes lowered costs.

Here‘s a quick rundown of the PEX varieties you‘ll encounter and their differences:

• PEX-a: Created using the Engel method, PEX-a is highly flexible and durable. It‘s the most resistant to freezing and ideal for tight bends.

• PEX-b: Uses the Silane method to offer moderate flexibility. More affordable but not as bendable as PEX-a.

• PEX-c: Manufactured via electron beam processing, PEX-c is rigid piping that is easy to install but can‘t handle tight bends.

I generally recommend PEX-a or PEX-b for shower valves since they can fit in cramped spaces behind walls and maneuver around obstacles. The bend radius for PEX-a can be as tight as 5-6 times the outside diameter of the tubing.

Below are some of the top reasons I choose PEX over copper or other rigid pipe materials:

Benefits of Using PEX for Shower Valves

• Corrosion proof: PEX won‘t corrode from water exposure or minerals like copper does

• Damage resistant: PEX can expand and contract without bursting. It withstands freezing better than metal.

• Flexible: Easier to route PEX lines than rigid copper or CPVC pipes.

• Fewer connections: Long PEX runs require fewer fittings and potential leak points.

• Ease of install: PEX doesn‘t require soldering. Push-fit fittings make DIY projects simpler.

• Cost savings: PEX tubing is around $2-$4 per foot compared to $10-$15 for copper. Installs also take less time.

According to studies by Brunel University, PEX pipes have an average lifespan of 50-70 years. That‘s 1.5 to 2.5 times longer than copper pipe systems. When installed properly, PEX is extremely durable in shower applications.

Now let‘s get into the specifics on how to install a shower valve using PEX…

Step-by-Step PEX Shower Valve Installation

Replacing a shower valve requires care to get right. Here are the step-by-step instructions I use for flawless installs:

Necessary Tools and Materials

• PEX tubing (PEX-a or PEX-b recommended)
• PEX elbows, tees, adapters, etc.
• PEX crimp rings + crimp ring pliers
• Pipe cutter
• Adjustable wrench
• Emery cloth/pipe brush

Step 1: Turn Off Water Supply

Always start by shutting off the hot and cold water lines feeding the shower valve via the angle stops. This lets you work safely without flooding.

Step 2: Remove Old Valve and Lines

Take out the handle trim and cover plates from the worn out shower valve. Remove the valve mounting screws or nuts and take it out. Also detach the supply lines and shower arm piping.

Step 3: Clean and Sand Fittings

Use emery cloth or a wire pipe brush to clean and scuff up the existing fittings you‘llreconnect the new PEX lines to. This helps create a watertight seal.

Step 4: Install New Shower Valve

Place the replacement shower valve into the wall opening and secure it per the manufacturer instructions. Most use mounting screws or retaining nuts.

Step 5: Run PEX Supply Lines

Measure and cut segments of PEX to run from the angle stops to the inlet ports on the new valve. Use elbow fittings to angle the tubing. Slip on crimp rings and use crimp ring pliers to attach.

Step 6: Connect Outlet to Shower Arm

In the same way, measure and cut a length of PEX to run from the new valve‘s outlet to the existing shower arm piping. Attach with a tee or elbow fitting and crimp ring.

Step 7: Insulate, Test and Finish Up

Wrap any exposed PEX with foam insulation to prevent heat loss and condensation. Turn the water back on and check for leaks. Replace all trim and handles when complete.

Pro Tip: Preventing Pressure Spikes

Installing a whole house water pressure regulator is wise to avoid spikes over 80 PSI that could damage PEX over time.

And that‘s all there is to it! The flexibility of the PEX tubing lets you easily route the plumbing lines. The push-fit fittings simplify the connections. In an afternoon, even a DIYer can transform their shower with a new valve.

Next, let‘s look at…

PEX Size and Specs for Shower Valves

Choosing the right size PEX is critical for proper water flow while avoiding leaks:

Supply Lines

• 1/2 inch PEX tubing is the minimum recommended size for adequate flow to the shower valve.

• For high water pressure, large rain shower heads, or long supply line runs, 3/4 inch PEX is a better choice.

• Match the size of the connectors on your shut-off valves (usually 1/2" or 3/4" FIP or sweat).

Outlet Line to Shower Head

• Standard shower arms are typically 1/2" male NPT threads. Size the PEX accordingly.

• Some rain shower heads use a larger 3/4" outlet line. Verify your model.

Underground Lines

• For PEX lines over 50 feet or supplying multiple fixtures, use 3/4" or 1" tubing.

• Insulate underground PEX to guard against temperature fluctuations.

Pressure and Temperature Ratings

• PEX tubing has a maximum pressure of 160 PSI at 73°F and 100 PSI at 180°F.

• PEX can handle hot water up to 200°F but aims for a max of 180°F.

Always refer to the manufacturer‘s specs for the PEX variety you choose. Using improper tubing can lead to catastrophic failures.

Connecting PEX to Shower Valves and Arms

While PEX is great for runs of tubing, you need metal fittings for shower valves and arms:

• Use a PEX-to-male threaded adapter to connect to shower valve inlets.

• A PEX-to-female threaded adapter fits a shower arm outlet.

• Ensure any chrome-finished fittings use the rigid PEX-c piping for a seamless look.

• For tub spouts, utilize a PEX-to-male threaded adapter in most cases.

Take care to follow the manufacturer‘s instructions for these mixed material connections. Improper assembly can lead to dangerous leaks.

PEX for Full Shower Plumbing Systems

Beyond just the shower valve itself, PEX works extremely well for:

• Hot and cold water supply lines running to the valve.

• The shower arm and piping leading to the shower head.

• Drain lines using larger diameter PEX.

• Bathtub fill valves and piping.

Using PEX for the entire plumbing system allows simplicity and flexibility. Continuous homerun manifolds reduce connections versus trunk and branch.

Proper hangers and strapping are crucial to support long uninterrupted PEX runs. I recommend hangers every 32" for maximum stability.

The Expert Verdict: PEX vs. Copper

While copper is a tried and true standard, PEX offers major benefits:

PEX Pros

• Easier DIY installation. No torches for soldering!

• Bends around obstacles in tight spaces.

• Less prone to flow loss from mineral deposits.

• Lower cost. Around $2 per foot compared to $10 for copper.

Copper Pros

• Familiar material for plumbers. Universally approved by codes.

• Can withstand very high water pressures over 160 PSI.

• Neater appearance, especially for chrome finished valves.

• Excellent long term performance with few failures when installed correctly.

The Bottom Line

In my professional opinion, PEX is the best solution for most shower valve replacements. The huge time and cost savings outweigh the minor pros of copper. Combining short sections of copper with PEX runs gives you the best of both worlds.

Step-by-Step: Replacing a Bathtub Valve with PEX

Replacing a tub valve works very similarly to a shower valve using PEX:

1. Turn off the water supply and remove the old fill valve.

2. Clean and prepare the opening and existing pipes.

3. Install the new tub fill valve and mount it securely.

4. Connect PEX supply lines from the valve to the 1/2" angle stops.

5. Run a PEX outlet line using an adapter to the tub spout.

6. Insulate lines as needed and test for leaks before finishing.

The main difference is utilizing a PEX-to-male threaded adapter to connect to the tub spout outlet. Make sure to use Teflon tape on the adapter threads for a watertight seal.

Maintaining Your PEX Shower Valves

PEX will easily outlast the valve itself, but simple maintenance helps:

• Inspect annually for leaks, bulges or dripping lines.

• Check water pressure and install a regulator if over 80 PSI.

• Replace worn shower heads causing spikes. Use low-flow models.

• Keep lines away from chemicals like paint strippers that can degrade PEX.

• Insulate properly to prevent cold weather damage.

Catching minor issues early prevents big headaches down the road. Overall, you can expect decades of reliable service from a PEX plumbing system with simple periodic maintenance.

Conclusion: Why I Recommend PEX for Shower Valves

In sum, as an experienced home improvement pro, I strongly recommend using PEX for shower valve replacements. The flexibility, safety, and cost savings versus copper make PEX the superior choice in most residential settings.

By following the detailed steps provided and using quality fittings, you can tackle a shower valve install yourself and save hundreds compared to hiring a plumber. Or, share this guide with your contractor so they can take advantage of PEX for faster, easier shower upgrades.

I hope you found the information helpful. Let me know if you have any other plumbing questions!

Sincerely,

Lillie Gabler
Home Improvement Expert