PEX & Copper: Install Compression Fittings Like a PRO!

Mastering Copper to PEX Compression Fittings: A Step-by-Step Guide

This guide provides a detailed walkthrough on how to properly install a "copper to pex compression fitting." We’ll cover the necessary tools, best practices, and potential pitfalls to ensure a leak-free and durable connection. This method allows you to join copper and PEX pipes without soldering, making it an ideal solution for DIYers and professionals alike.

Understanding Compression Fittings

Compression fittings offer a mechanical means of joining pipes. Instead of soldering, these fittings use pressure to create a tight seal. They consist of several components: the fitting body, a compression nut, and a compression ring (also known as a ferrule or olive). When the nut is tightened, the ring compresses against the pipe, forming a watertight seal.

Advantages of Compression Fittings

• No Soldering Required: Eliminates the need for heat, flux, and soldering skills.
• Easy Installation: Relatively simple to install with basic tools.
• Suitable for Tight Spaces: Can be used in areas where soldering is difficult or dangerous.
• Demountable: Can be disassembled and reassembled (though not recommended multiple times due to potential wear on the compression ring).

Disadvantages of Compression Fittings

• Potential for Leaks: If not installed correctly, compression fittings are more prone to leaks than soldered joints.
• Space Requirements: Compression fittings are often bulkier than soldered joints, requiring more space.
• Cost: Generally more expensive than soldering materials.

Tools and Materials Needed

Before you begin, gather the following tools and materials:

• Copper to PEX Compression Fitting(s): Ensure the fitting is the correct size for both your copper and PEX pipes.
• PEX Pipe Cutter: Provides a clean, square cut for PEX pipe. A rotary cutter is preferred.
• Copper Pipe Cutter: Necessary for cutting copper pipe, ensuring a clean, burr-free edge.
• Deburring Tool: Used to remove any burrs or sharp edges from the cut ends of both the copper and PEX pipes. This is CRUCIAL.
• Two Adjustable Wrenches: One to hold the fitting body steady, and the other to tighten the compression nut.
• Measuring Tape: For accurate measurements and pipe cutting.
• Pencil or Marker: For marking pipe lengths.
• Clean Rags: For cleaning pipe surfaces.
• Pipe Thread Sealant (optional): Can provide an extra layer of protection against leaks, especially on older copper pipes. Teflon tape or pipe dope is suitable.

Step-by-Step Installation Guide

Follow these steps carefully to ensure a secure and leak-free connection:

1. Prepare the Copper Pipe:
   • Measure and mark the desired length of copper pipe.
   • Use the copper pipe cutter to make a clean, square cut.
   • Use the deburring tool to remove any burrs from the inside and outside edges of the copper pipe.
   • Clean the copper pipe with a clean rag to remove any dirt or oxidation.
2. Prepare the PEX Pipe:
   • Measure and mark the desired length of PEX pipe.
   • Use the PEX pipe cutter to make a clean, square cut.
   • Use the deburring tool to remove any burrs from the inside and outside edges of the PEX pipe.
   • Ensure the PEX pipe is perfectly round. If it is ovalized, use a PEX reforming tool to restore its shape.
3. Assemble the Fitting:
   • Important: Refer to the specific instructions included with your fitting, as assembly order can vary slightly. This guide assumes the common assembly order.
   • Slide the compression nut onto the copper pipe.
   • Slide the compression ring (ferrule) onto the copper pipe, following the nut. Make sure it’s oriented correctly – the tapered side typically faces towards the fitting body.
   • Repeat the same steps for the PEX pipe.
4. Connect to the Fitting Body:
   • Insert the copper pipe into the designated side of the fitting body until it is fully seated.
   • Insert the PEX pipe into the designated side of the fitting body until it is fully seated.
5. Tighten the Compression Nuts:
   • By Hand: Carefully tighten the compression nuts by hand as much as possible.
   • With Wrenches: Use two adjustable wrenches. Place one wrench on the fitting body to hold it steady, and the other wrench on the compression nut.
   • Tighten the nut according to the manufacturer’s specifications. Over-tightening can damage the fitting and cause leaks. A good rule of thumb is to tighten the nut another one-half to three-quarters of a turn beyond hand-tight.
6. Testing for Leaks:
   • Slowly turn on the water supply.
   • Carefully inspect the fitting for leaks.
   • If you detect a leak, slightly tighten the compression nut (no more than a quarter turn at a time). Retest and repeat if necessary.
   • If the fitting continues to leak after several attempts, disassemble it and inspect the compression ring and pipe surfaces for damage. Consider replacing the fitting and re-doing the connection.

Troubleshooting

Problem	Possible Cause	Solution
Leaking Fitting	Loose nut	Tighten the nut slightly.
Leaking Fitting	Damaged compression ring	Replace the compression ring.
Leaking Fitting	Scratched or damaged pipe	Cut the pipe back to a clean section and try again.
Difficult to Tighten	Threads are damaged or dirty	Clean the threads or replace the fitting. Apply a small amount of pipe thread sealant to the threads.
Ovalized PEX Pipe	PEX pipe not properly rounded	Use a PEX reforming tool to restore the pipe’s shape.

Safety Precautions

• Always turn off the water supply before working on plumbing.
• Wear safety glasses to protect your eyes from debris.
• Use caution when working with tools.
• If you are unsure about any step of the installation process, consult a qualified plumber.

So, you’ve got the lowdown on using a copper to pex compression fitting! Pretty straightforward, right? Now get out there and tackle that plumbing project – you’ve got this!