Compression vs Capillary Fittings

Choosing the right type of fitting is essential for the success of any plumbing or heating installation. Compression fittings and Capillary fittings are two of the most traditional methods around and offer distinct benefits depending on the application.

Understanding their differences, strengths, and use cases can help you make the best decision for your project. This guide provides an in-depth comparison of Compression and Capillary fittings, covering their features, benefits, installation processes, and ideal uses.

What Are Capillary Fittings?

Capillary Fittings, also known as Soldered Fittings, are the most traditional plumbing connectors that use capillary action to form a secure bond between the fitting and the pipe. These fittings are made of copper, brass or bronze, and require soldering to seal the joint. Capillary fittings are commonly used in domestic and commercial plumbing, heating, and cooling systems.

Capillary

Flowflex Capillary fittings are designed for precision and reliability in copper pipe connections. Featuring a capillary action for secure, leak-free joints, they ensure ease of installation and longevity. Ideal for domestic and commercial applications, these fittings provide a neat, robust, and corrosion-resistant solution for HVAC systems.

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Key Features of a Capillary Connection

• Fitting Body: Made of copper or brass, designed to fit snugly around copper pipe manufactured to BS EN 1057 standards.

• Copper Pipe: Copper tube manufactured to BS EN 1057 standards.

• Solder: A metal alloy used to bond the fitting and pipe together when heated.

• Flux: A chemical cleaning agent applied to the joint before soldering to prevent oxidation and ensure a strong and clean bond.

Advantages of Capillary Connections

• Strong, Permanent Joints
  Soldered joints create a durable, leak-proof seal that can withstand high pressure and temperature changes.

• Can Support Higher Pressures
  Depending on the choice of solder, Capillary Fittings can reach pressure ratings of PN25.

• Environmentally Friendly Material
  Copper is a sustainable and recyclable material, making capillary fittings an environmentally friendly option.

• Compact Design
  Soldered fittings are sleek and low-profile, making them ideal for exposed installations where aesthetics matter or tight spaces where access is limited.

• Cost-Effective
  Generally cheaper than other types of fittings, making them popular for large installations.

• Highly Reliable
  Minimal risk of leaks when installed correctly due to the solid bond between the fitting and the pipe.

Disadvantages of Capillary Connections

• Requires Open Flame
  The use of a torch introduces safety risks, particularly in areas where flammable materials are present or where heat is restricted.

• Higher Skill Level Required
  Proper soldering technique is crucial; poor preparation or overheating can result in weak joints or leaks.

What Are Compression Fittings?

Compression fittings are widely used in plumbing, heating, and gas installations because of their simplicity and reliability. They consist of three main components: a compression nut, a compression ring (also known as an olive), and a fitting body. The olive compresses against the pipe and the fitting body as the nut is tightened, forming a watertight seal.

Compression

Flowflex Compression fittings, including Type A, Type B, PEX, and Large Bronze Flange Fittings, offer secure, leak-free connections, easy installation, and durability. They ensure flexibility in plumbing, are corrosion-resistant, and provide robust performance, enhancing the efficiency and reliability of HVAC systems.

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Key Components of Compression Connection

• Compression Nut: A threaded nut that tightens over the fitting body.

• Compression Ring (or Olive): A metal ring that compresses between the nut and fitting body to form a seal.

• Fitting Body: The main part of the fitting that connects to the pipe.

• Pipework: Copper, Plastic or Steel Pipe.

How Compression Fittings Work

When the compression nut is tightened, the olive compresses between the pipe and the fitting body, creating a leak-proof seal. The seal is formed by metal-on-metal contact, making it robust and durable without the need for heat or solder.

Advantages of Compression Fittings

1. Heat-Free Connections
   Compression fittings do not require soldering or welding, making them ideal for construction sites where hot works are restricted or where open flames are not safe.

2. Ease of Assembly
   Compression joints are easy to understand and install, making them suitable for both DIYers and professionals. Simply slide the pipe into the fitting, add the olive, and tighten the nut.

3. No Special Tools Needed
   Only basic tools, like adjustable spanners, are required to install compression fittings - no expensive or specialised equipment necessary.

4. Easy to Disassemble
   If maintenance or disassembly is needed, compression fittings can be undone and reassembled without damaging the connection.

5. Reusable Components
   Compression fittings can be reused in future installations. Simply replace the olive with a new one from the same manufacturer, as the old olive remains fixed to the original pipe.

6. Installation in Wet Conditions
   These fittings can be installed in wet environments, speeding up repair times and making them ideal for leak fixes.

7. Environmentally Friendly Materials
   Copper alloys are sustainable and recyclable materials, making Compression Fittings an environmentally friendly option.

8. Compatible With Multiple Types of Pipe
   Compression fittings are not limited to copper; they work with plastic, carbon steel, and stainless steel pipes, making them adaptable to multiple systems.

Best Use Cases For Compression Fittings

1. Demountable Installations
   Compression fittings are ideal for installations that may need to be disassembled occasionally or even frequently, offering a reliable and easy to connect/disconnect solution.

2. Mixed Material Connections
   Compression fittings are versatile and can connect copper, plastic, and steel pipework, making them an excellent choice when you need to mix different materials within your installation.

3. Heat Free Installations
   Compression fittings are a great option for installations where open flames are prohibited, providing a safe and efficient connection without the need for soldering.

4. Low Skilled Installations
   Compression fittings are perfect for both DIY home projects and commercial applications that require less specialised skills. Their ease of use, straightforward connections, and minimal tooling make them an ideal choice for a wide range of users.

Comparing Compression Fittings and Capillary Fittings

Which One Should You Choose?

Choosing between Compression and Capillary fittings depends on your project’s specific needs, skill level, and the installation environment:

Choose Compression Fittings if:

• You need a quick, flame-free installation that’s easy to manage.

• The project involves connecting mixed materials or requires reusability.

• You prefer a straightforward, tool-based installation with minimal skill requirements.

Choose Capillary Fittings if:

• You want a cost-effective, traditional approach and have the skills for proper soldering.

• The project allows for more time and demands precision with soldering techniques.

• You need to achieve higher pressure ratings.

Conclusion

Both Compression and Capillary fittings bring distinct advantages to plumbing and heating installations. Compression fittings offer a versatile, reusable, and flame-free solution, making them ideal for quick repairs and connecting different materials. Capillary fittings, on the other hand, provide a traditional, reliable, and cost-effective option that can achieve higher pressure ratings, perfect for those with the skills to handle soldering techniques.

By understanding the strengths and limitations of each fitting type, you can make the best choice for your next project, ensuring a secure, efficient, and professional installation.

Compression

Capillary