PEX, or cross-linked polyethylene tubing, has become a popular option for plumbing in recent years. With its flexibility, resistance to temperature extremes, and other benefits, PEX has replaced copper piping in many homes. However, there is some debate around whether PEX can be used for all plumbing applications, including shower valves. In this article, we’ll examine the key considerations in using PEX for shower valves.
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What is PEX?
PEX stands for cross-linked polyethylene. It is a flexible plastic tubing that is used for water supply lines in residential and commercial buildings. Here are some key characteristics of PEX:
- Made from polyethylene plastic resin that has been cross-linked through chemical bonds
- Available in red, blue and white colors for hot, cold and recycled water lines
- Flexible and bendable – can make tight turns without joints
- Withstands freezing temperatures without bursting
- Resistant to scale buildup and chlorine corrosion
- Simple push-fit or crimp connections
- Typically 1/2″ to 1″ in diameter for residential use
The cross-linking process strengthens the molecular structure of PEX and makes it more durable and heat resistant compared to standard polyethylene tubing. PEX tubing is now commonplace in newly constructed homes, though some plumbers still prefer copper pipes.
Benefits of PEX for Plumbing
PEX offers a range of benefits that have made it a top choice for residential water supply lines:
Flexible – PEX tubing is flexible and bendable, which makes installation easier. There is no need for elbow joints to turn corners. This also reduces potential leak points.
Freeze resistant – PEX can expand and contract with water pressure changes. It can withstand freezing temperatures without bursting or cracking.
Corrosion proof – PEX is resistant to chlorine and mineral deposits that can corrode metal pipes. The smooth inner wall helps reduce scale buildup.
Simple connections – PEX tubing uses simple push-fit or crimp style fittings. No soldering or gluing is needed during installation.
Durable – PEX can last over 50 years without failure or leakage issues. The cross-linked structure makes it very strong and durable.
Noise reduction – PEX dampens vibrations and water hammer. This leads to quieter operation compared to metal pipes.
With these advantages, PEX has become a top choice for plumbers and homeowners looking to replace or install new water lines. The flexibility, leak resistance, and longevity of PEX make it an ideal solution for home water supply plumbing.
Potential Concerns with PEX
While PEX has many positive attributes, there are also some areas of concern to consider:
UV light degradation – PEX tubing can become brittle and crack over time when exposed to UV rays. Manufacturers recommend keeping PEX out of direct sunlight.
Rodent damage – Unlike metal, PEX tubing can be chewed through by rodents. Keeping lines protected is important in rodent-prone areas.
Unsuitable for very hot water – PEX has a maximum service temperature of 200°F. It cannot safely handle scalding hot water temperatures above this point.
Difficult repairs – PEX cannot be spliced or welded if damaged. The entire damaged section would need replacement.
Chemical sensitivity – Oil-based lubricants, solvents, and caustic cleaning agents can cause PEX to crack or deform.
While most of these concerns are minor or easily managed, they are important to keep in mind if considering PEX plumbing. Proper installation and care is needed to maximize its advantages while avoiding potential problems.
Using PEX for Shower Valves
When it comes to shower valves and mixing valves, PEX has some limitations to consider:
High temperature rating – Shower valves mix hot and cold water, so the plumbing must handle hot water straight from the water heater, often 120°F to 140°F . PEX is only rated for a maximum temperature of 200°F.
Pressure balances – Shower valves have pressure balance devices that compensate for pressure changes between hot and cold water supply. PEX’s flexibility may interfere with the valves’ ability to properly balance pressure.
Wall support – Shower valves require solid anchoring to the wall structure. The flexibility of PEX may make proper wall support difficult compared to rigid copper pipes.
Difficult fittings – The small spaces behind shower walls can make it hard to properly install PEX push-fit or crimp fittings. Copper pipes allow for soldering even in tight spaces.
While some plumbers argue PEX can be carefully used on shower valves, others recommend against it due to the high temperatures and pressure balancing concerns. Using a rigid pipe like copper or CPVC may be preferable for the short branch lines to shower valves. PEX could then be used for the main water supply lines in the walls or ceiling.
Best Practices for PEX Shower Valves
If you do decide to use PEX for shower valve supply lines, here are some best practices to follow:
– Keep hot water lines as short as possible, and insulate lines to protect PEX from excessive heat.
– Use commercially rated valve boxes or blocking in walls to properly anchor valves.
– Support PEX lines to prevent sagging and maintain pitch for drainage.
– Use angle stops valves and integrated supply line fittings to simplify connections.
– Ensure a professional crimp or tight push-fit connection – no loose fittings.
– Carefully test for leaks under full pressure before closing up walls.
– Only use PEX tubing rated for 200°F hot water supply.
– Consider using metal supply lines for the final 2-3 feet into the valve.
PEX-Compatible Shower Valves
Certain shower valve models may be better suited for use with PEX supply lines. When selecting a PEX-compatible shower valve, look for these features:
– 200°F or higher temperature rating.
– Reinforced inlets and outlets to prevent crushing.
– Ball-style inlets for flexible, kink-free connections.
– Pressure balance cartridge or thermostatic mixing valve.
– Integrated service stops or angle stop valve connections.
– Compact single-body design to allow tight mounting.
Some shower valve brands that are commonly used with PEX include:
- Moen – Many PosiTemp models
- Delta – R10000 series, Monitor series
- Kohler – K-304 models
- Grohe – Several thermostatic mixing valves
- Hansgrohe – Axor thermostatic valves
- American Standard – Reliant 3 models
Always check the manufacturer’s specifications and installation guidelines when using PEX supply lines. Some high-end designer faucets may not specify PEX compatibility.
Conclusion
PEX tubing can potentially be used for shower valve supply lines in some circumstances. However, it is not an ideal application for PEX due to the high water temperatures and need for stable wall support. PEX limitations may also affect pressure balancing performance in some shower valves.
While careful installation using short supply lines and proper fittings may allow PEX to function on some shower valves, copper or CPVC pipes are generally a better choice. Consult the shower valve manufacturer’s instructions to confirm compatibility with PEX. With careful planning and execution, PEX plumbing can work successfully throughout the home, even for demanding applications like shower valves.
| Material | Benefits | Limitations |
|---|---|---|
| PEX |
|
|
| Copper |
|
|
Key Takeaways
- PEX has temperature limits that may impact use on shower valves
- Copper pipes may provide better support for shower valves
- Short PEX lines with proper fittings may work in some cases
- Always consult manufacturer instructions for PEX compatibility
- Careful installation is required when using PEX for shower valves