PEX (crosslinked polyethylene) has become one of the most popular piping materials in modern plumbing systems. PEX's flexibility, corrosion resistance, and easy installation make it an ideal choice for both DIYers and professionals. However, proper installation is crucial to ensure PEX pipes meet their long lifespan potential while avoiding leaks or performance issues. This comprehensive guide will walk through the entire PEX installation process - from material selection to tools needed to step-by-step construction details. Follow these best practices to install efficient, durable PEX plumbing that will provide decades of reliable service.
Choosing Your PEX Piping Material
PEX piping comes in a variety of grades and specifications to suit different applications. The three main types are:
PEX-A: This pipe undergoes cold expansion to induce crosslinking. It offers the best freeze-crack and temperature resistance. PEX-A provides a lifespan beyond long-term durability according to standards. It is the premium grade for critical applications like potable plumbing.
PEX-B: Uses chemicals like silane to initiate cross-linking. PEX-B costs less but has reduced temperature ratings versus PEX-A. It still provides 25+ years of durability. PEX-B works for non-critical uses like radiant floor heating.
PEX-C: Crosslinking gets induced by electron beam radiation. PEX-C is also moderately priced but has lowered freeze resistance. It serves low-pressure applications like hydronic distribution tubes.
Additional factors like pipe dimensions, pressure ratings, and 3rd party certifications should also be considered when selecting PEX piping to ensure it meets applicable building codes. Consult manufacturer specifications to choose the ideal PEX material for your plumbing application.
Essential Tools for PEX Installation
Installing PEX piping properly requires having the right tools on hand. While some basic DIY tools may suffice, specialized PEX installation tools are recommended to complete connections correctly. Essential PEX tools include:
- Tubing Cutter: A PEX tubing cutter makes straight, burr-free cuts through the tubing quickly.
- Crimp Tools: PEX crimp tools securely clamp crimp rings to join tubing and fittings. Avoid using regular pliers.
- Pipe Deburring Tool: Used after cutting to smooth PEX edges before fitting connections.
- Depth Gauge: Allows proper setting of the pipe inserts fittings into the PEX tubing.
- PEX Jaw Pliers: Designed to accurately close clamps on PEX barb fittings without damage.
- Expansion Tools: For cold-expansion style PEX connections. Includes hand-held and battery-powered versions.
- Manifolds: Pre-fitted port blocks to connect multiple PEX lines in parallel.
Having these purpose-built PEX tools on hand will make installations much easier and help achieve reliable joints.
Prep Work: Sizing, Planning, and Pre-Assembly
Careful planning and preparation are key before physically installing PEX lines. Always follow these steps:
1. Calculate Demand: Estimate the water demand for each fixture to size supply lines properly.
2. Create a Rough Plumbing Plan: Sketch proposed pipe routing from supply origin to endpoints.
3. Choose Fittings: Select the required elbows, tees, adapters, and other fittings to execute your plan.
4. Size the PEX Tubing: Use tubing of the appropriate diameter for each pipe run based on peak demand.
5. Pre-assemble Components: Join any assemblies like manifolds ahead of time for efficient installation.
6. Set Supports: Install hangers, braces, and supports where needed to hold pipe routes in place.
7. Review Plans: Double-check all measurements and fitting selections before starting.
Advance planning and dry fits will make the actual PEX installation much smoother.
Installing PEX Water Supply Lines
With materials and plans ready, now we walk through actually installing PEX piping for water delivery throughout a building:
1. Shut Off Water: Turn off the main water supply and open taps to depressurize lines.
2. Start at Supply: Plan the PEX routing beginning from the main water supply line. Run lines to each fixture.
3. Anchor PEX: Secure piping along framing with hangers every 32 inches and within 8 inches of each junction.
4. Make Connections: Use proper tools to connect PEX tubing and fittings at each junction point. Follow manufacturer instructions.
5. Maintain Support: Continue anchoring the PEX along the entire route to prevent sagging and strain on joints.
6. Attach Fixtures: Use flexible tubing or valves to connect the PEX piping to plumbing fixtures.
7. Pressure Test: Cap all endpoints. Slowly turn on the water and check for leaks up to 150 PSI maximum test pressure.
8. Insulate if Needed: For hot water lines or pipes in uninsulated areas, wrap PEX in foam tubing to minimize heat loss.
Following this disciplined process will yield reliable PEX plumbing free of leaks, bursts or crimp failures over decades of operational life.
Installing PEX for Radiant Floor Heating
In addition to water supply plumbing, PEX tubing is also ideally suited for in-floor radiant heating systems thanks to its flexibility and heat resistance:
1. Plan the Layout: Sketch a looped piping layout to evenly distribute heat across the entire floor area.
2. Select a Manifold: Choose a PEX manifold with enough ports for the required number of heating loops.
3. Anchor Manifold: Mount the manifold assembly on brackets close to the future boiler connection point.
4. Lay the Loops: Use PEX-A or PEX-B tubing to lay continuous loops across the floor area per the plan.
5. Regulate Flow: Install balancers on each manifold outlet to evenly distribute hot water between loops.
6. Cover Pipes: After pressure testing, cover the tubing with thin-set cement or a gypsum layer. Avoid sharp objects.
7. Finish Flooring: Apply chosen finished floor surface over the tubing, like tile, laminate, or carpeting. Follow flooring instructions.
8. Control Temperature: Connect a thermostat with thermocouple sensors to actively regulate the boiler water temperature.
The result is a comfortable in-floor heating system with steady, even warmth and high energy efficiency.
Cold Climate PEX Installation Tips
In cold regions, PEX's flexibility makes it well-suited for freeze-resistant plumbing. However, proper installation is vital to avoid winter damage:
- Insulate All Pipes: Fully wrap PEX lines in heated spaces to minimize heat loss and prevent exterior freezing.
- Pitch Horizontal Pipes: Slope horizontal lines ≥ 0.5 cm per meter to allow drainage to avoid freeze expansion damage.
- No Exposed Pipes: Any pipes in unheated areas must be buried below the frost line or actively heat traced.
- Deeply Bury Underground: Outdoor burial depth should exceed the deepest freeze penetration zone for the climate.
- Allow Movement: Anchor lines to ceilings or walls using elastic suspension hardware to accommodate winter movement.
- Install Shutoffs: Shutoff valves inside before pipes exit a heated space allow isolation if freezing occurs.
- Upgrade to PEX-A: For extremely low temperatures, use PEX-A for its superior freeze-crack resistance.
Adhering to these cold climate recommendations helps prevent the risky and costly damage associated with frozen, burst plumbing systems.
Common PEX Plumbing Joints
Several techniques exist for connecting PEX tubing to itself or to fittings and fixtures. The most popular options are:
Crimp Ring Joints
- Cut tubing squarely and deburr the edge. Slip a crimp ring over the end.
- Fully insert the tubing into the fitting until it bottoms out.
- Position the ring 1/8" from the end and use PEX crimping pliers to tightly compress it.
Compression Joints
- Slide a compression sleeve over the end of the PEX pipe.
- Insert tubing into the compression fitting until fully seated.
- Tighten the nut on the fitting until snug per manufacturer specs.
Cold Expansion Joints
- Mark the insertion depth on the PEX tubing.
- Use an expander tool to simultaneously stretch the pipe mouth and form an indentation.
- Quickly push the expanded end into the fitting to create a tight interference fit.
Clamp Joints
- For barb fittings, slide a hose clamp over the end of the pipe.
- Fully insert the tubing until it stops.
- Position and close the hose clamp over the barbed section with pliers.
Proper joint installation is vital - always follow manufacturer guidelines and use appropriate tools to create secure, leak-free connections that will last.
Troubleshooting Common PEX Installation Mistakes
Despite its overall ease, some common pitfalls can undermine successful PEX plumbing:
Overheating: PEX can be damaged above 180°F. Ensure hot water heaters are set properly.
Undercutting Tubing: Cutting PEX too short prevents full fitting insertion causing leaks.
Forgetting to Deburr: Jagged PEX edges after cutting will damage seals. Always smooth ends.
Not Fully Inserting: The pipe must reach the fitting stop to create a flush junction.
Misaligned Crimp Rings: Rings must be perfectly centered over the joint for an even seal.
Incorrect Tools: Using pliers instead of PEX crimp tools can distort connections.
Over-Tightening Clamps: Excessive torque weakens the tube and causes flow restriction.
Insufficient Support: Anchors are needed every 32” to avoid pipe stress and joint separation.
Avoiding these mistakes during PEX installations will prevent headaches down the road and ensure your plumbing functions smoothly for decades to come.
Maintenance Best Practices
While PEX tubing is highly durable, some periodic maintenance helps identify any potential issues:
- Check fittings and valves for leaks during routine operation and prior to periods of heavy use.
- Flush pipes regularly to clear out any sediment, particularly in hard water areas.
- Periodically disinfect pipes using chlorine if water quality degrades over time.
- Evaluate pipe condition for any damage during renovations or basement upgrades.
- Ensure pumps and pressure-reducing valves are operating properly to avoid surges.
- Test and reset temperature and pressure relief valves annually as a safety precaution.
Properly installed PEX can last 50+ years. But periodically inspecting and maintaining your plumbing helps maximize this potential lifetime.
Re-PIPING with PEX
For outdated metal pipe systems, consider re-piping with PEX when renovating or remodeling:
1. Review Scope: Inspect the full plumbing system to determine the feasibility and scope of re-piping.
2. Design Plan: Create a complete plumbing layout maximizing PEX for water delivery and drainage.
3. Reroute Utilities: Temporarily relocate any utilities crossing future PEX routes.
4. Remove Old Piping: Dismantle existing plumbing and clear debris.
5. Install New PEX: Follow the earlier installation process to replace with efficient PEX plumbing.
6. Update Fixtures: Replace outdated plumbing fixtures and appliances with modern water-saving versions.
7. Reconnect Utilities: Securely reinstall any previously displaced utilities.
8. Confirm Performance: Thoroughly test the new PEX system across pressure, temperature, and flow extremes.
Re-PIPING provides an opportunity to refresh entire plumbing systems with flexible, maintenance-free PEX piping that saves energy and avoids corrosion.
PEX tubing makes plumbing repairs, renovations, and new construction much simpler thanks to its lightweight flexibility, corrosion resistance, and reduced joint connections versus rigid metal piping. By following the material selection, tools, installation, and maintenance best practices outlined in this guide, both DIY and professional plumbers can implement efficient and durable PEX plumbing systems. Taking the time to properly plan, prepare and install PEX using appropriate techniques will ensure leaks, bursts, and blockages become a thing of the past. Your PEX plumbing will continue providing high flows and low maintenance operations for decades to come.
