How to Join Copper Pipe: Solder, Compression, and Push-Fit Fittings Explained

Copper pipe remains the material of choice for central heating and hot water systems in the UK. It handles high temperatures, lasts decades, and is supported by a wide range of fittings. The question most plumbers and keen DIYers ask — especially when they haven't done much pipework — is: which type of joint should I use? This guide covers the three main methods for joining copper pipe: soldered (end feed and Yorkshire), compression, and push-fit. We'll explain how each works, when to use it, and the common mistakes to avoid.

The Three Ways to Join Copper Pipe

Each jointing method uses a different mechanism to create a watertight seal:

• Solder fittings (end feed and Yorkshire/integral solder ring) — the copper fitting is silver-soldered or brazed to the pipe using heat and solder, creating a permanent metal-to-metal bond
• Compression fittings — a brass olive is compressed between the fitting body and cap nut, gripping the pipe and sealing it without heat
• Push-fit fittings (e.g. Speedfit, Hep2O) — a grab ring and O-ring inside the fitting seal and retain the pipe on insertion, requiring no tools beyond a pipe cutter

Soldered Copper Fittings

End Feed vs Yorkshire (Integral Solder)

Both are capillary fittings — they work by drawing molten solder into the tiny gap between fitting and pipe by capillary action. The difference is where the solder comes from:

• End feed fittings have no pre-loaded solder. You apply solder wire to the lip of the fitting as you heat it, and the solder flows in by capillary action. Cheaper per fitting, but requires good solder technique.
• Yorkshire fittings (also called integral solder ring fittings) have a ring of solder pre-loaded inside the fitting. When you heat the fitting correctly, you see a ring of bright solder appear at the lip — this tells you the joint is made. No separate solder wire required.

When to Use Solder

Soldered joints are the right choice for:

• Permanent installations in walls, floors, or ceiling voids — slim profile, no access needed once installed
• Central heating pipework (the joint withstands system temperature and pressure indefinitely)
• Where a compression fitting is too bulky to fit in a tight space
• High-volume work where fitting cost matters — end feed fittings cost a fraction of compression

How to Make a Solder Joint

1. Cut the pipe square. Use a pipe slice or hacksaw. Deburr the inside edge with a reamer or file — a burr causes turbulence and traps flux, which leads to pinhole leaks.
2. Clean the pipe end and fitting socket. Use wire wool or emery cloth until the copper is bright. This is non-negotiable — oxide on copper prevents solder bonding.
3. Apply flux. Use a plumber's flux (paste or liquid) rated for copper and lead-free solder. Coat the pipe end and the inside of the fitting socket. Flux prevents re-oxidation during heating and helps solder flow.
4. Assemble and support the joint. Push the pipe fully into the fitting socket. Make sure the pipe is supported — a joint that moves while the solder is molten will fail.
5. Heat evenly. Use a blowtorch (propane or MAPP gas). Heat the body of the fitting, not the pipe — the pipe conducts heat back to the fitting. For Yorkshire fittings, stop heating when you see the solder ring appear at the lip. For end feed, touch solder wire to the lip gap — when it flows in and fills, stop.
6. Wipe and cool. Wipe excess flux with a damp cloth while the joint is still warm. Allow to cool before pressurising — never quench with water.

Fire safety: Always use a fire mat or heat guard behind the fitting when soldering near timber joists or plasterboard. The Building Regulations and insurance requirements apply regardless of how quick the job seems.

Lead-Free Solder

All copper pipework in domestic water installations must use lead-free solder (regulation since 1987, reinforced under WRAS and Water Regulations 1999). Look for solder wire and fittings marked as WRAS-approved for potable water use.

Compression Fittings

How They Work

A compression fitting has three components: the body, the olive (a soft brass or copper ring), and the cap nut. When the cap nut is tightened, it compresses the olive around the pipe, creating a grip and a seal simultaneously. No heat, no flux, no solder.

Embrass Peerless 12mm compression equal tee — part of our full compression fittings range

When to Use Compression

• Anywhere you might need to undo the joint in future — stop valves, service valves, connections to appliances
• Where you cannot safely use a torch (e.g., near gas pipes, in a confined loft space, over floorboards you can't protect)
• Mixing copper with chrome-plated pipe (compression fittings grip chrome pipe; solder does not bond to chrome)
• When the pipe is wet — solder won't take on a wet joint; compression will

Making a Compression Joint

1. Cut the pipe square and deburr.
2. Slide the cap nut onto the pipe, thread-end first, then slide on the olive.
3. Push the pipe fully into the fitting body until it bottoms out.
4. Hand-tighten the cap nut, then use two spanners — one to hold the fitting body, one to turn the cap nut. Tighten 1¼ to 1½ turns past hand-tight. No more.

Common mistake: Over-tightening. Crushing the olive past its design limits can split the fitting body or distort the olive so badly it no longer seals. If a compression joint leaks after initial tightening, a quarter-turn more is the fix — not half a turn.

Do not use PTFE tape on compression fittings. The olive provides the seal. Tape on the olive prevents it seating correctly.

Push-Fit Fittings

How They Work

Push-fit fittings (Speedfit, Hep2O, JG Speedfit, and own-brand equivalents) use a stainless steel grab ring to grip the pipe and an EPDM O-ring to seal it. The pipe is inserted until it clicks — no tools needed beyond cutting the pipe to length.

When to Use Push-Fit

• Temporary connections or joints that may need re-making (push-fit can be dismantled with a disconnect clip)
• Connecting to polybutylene or plastic barrier pipe as well as copper
• Where speed is the priority — push-fit is significantly faster than soldering or compression
• First-fix connections in new builds where pipe runs will be pressure-tested before plastering

Push-Fit on Copper Pipe

Always use a pipe insert (stiffener) when using push-fit fittings on copper pipe. Without an insert, the grab ring can distort the soft copper under system pressure. Inserts are usually included with quality fittings but check before installing — the fitting will appear to seal and then weep over time without one.

Temperature Ratings

Standard push-fit fittings are rated to 95°C at working pressure — sufficient for central heating systems. Check the fitting's temperature rating before using in high-temperature applications such as solar thermal or commercial heating.

Comparison at a Glance

Pipe Sizes: 15mm, 22mm, and 28mm

UK copper pipe comes in three main domestic sizes:

• 15mm — hot and cold water branches, radiator connections, most domestic hot/cold distribution
• 22mm — main hot/cold feeds, boiler primaries, high-flow circuits
• 28mm — large-bore central heating mains in bigger properties, high-output boiler primaries

All three sizes are available in end feed, Yorkshire, compression, and push-fit fittings. Reducers and adaptors are widely available for all common size transitions.

Copper Fittings and Pipe at APM Electricals, Acton

We stock a full range of copper fittings — end feed (Embrass Peerless and own-brand), Yorkshire integral solder, and compression — plus 15mm, 22mm, and 28mm copper pipe by the length. Same-day collection from our Acton trade counter, no minimum order.

If you're on the tools in West London, we're at 24 Western Avenue, Acton, London W3 7TZ. Open Monday to Saturday. Call ahead on 020 8702 8080 to check stock on specific items, or browse our plumbing range at apmi.uk.

Copper Pipe Jointing: Quick Reference

• Concealed permanent joints → end feed or Yorkshire solder
• Accessible joints, service valves, wet joints → compression
• Speed, temporary, plastic/copper mix → push-fit
• Always deburr before soldering or push-fit
• Clean to bright copper before soldering — no oxide, no joint
• Compression: 1¼ turns past hand-tight, no PTFE on olive
• Push-fit on copper: always fit a pipe insert/stiffener
• Use lead-free WRAS-approved solder for potable water

More trade guides on the APM trade blog, or visit us in Acton.