Plumbing: compression vs solder fittings

With a little know-how and the right tools, DIY plumbing jobs don’t need to be scary.

It’s amazing how many DIY enthusiasts remain nervous of attempting small DIY plumbing jobs around their home. To give you a hand and hopefully make plumbing less scary, here is some useful information on two of the more common fitting types – solder and compression fittings.

The term ‘solder’ refers to a metal alloy with a low melting point, usually lead and tin, that is used to join metals with higher melting points. The solder flux is melted using a heat gun, blowtorch or a soldering iron and can be used to join copper plumbing pipes. While it does take a bit of practice, it’s quite simple once you’ve got the hang of it. The pipes do need to be empty of water before you try to solder them, though, so you will need to drain the pipes before working on them.

When fitting a solder join, first give the end of the pipe a clean and a light sanding to roughen it up and make it easier for the solder to adhere to it. Apply a light coat of flux (which helps the solder to stick to the pipe), slip the fitting onto the pipe and turn it to make sure the flux is covering the area to be soldered. Wipe off any excess flux. Heat up the joint with a blowtorch until the solder melts when it touches the pipe. When it is hot enough, touch the solder wire to the pipe so that it melts and runs into the joint. Leave it to cool.

Soldering is quick and can be fun and can even be used to create art or things like lamps.

Compression fittings are made of polycop plastic, and comprise of a body, ferrules and an outer nut. They can obviously be used with polycop piping, and they can also be used with copper piping. Unfortunately, they are not certified for hot water pipes and so should be reserved for cold water plumbing. In addition to being used in joints, there are also compression fittings such as stop valves and taps.

Compression fittings are extremely easy to use and require no special skills or tools – just a shifting spanner or plumber’s wrench. To fit one, first switch off the water supply. Loosen the nut on the compression fitting so that the ferrule moves freely inside the housing, then slip it into place on the pipe, making sure the pipe goes all the way in. Now tighten the nut, which will compress the ferrule around the pipe and create a watertight seal. It does need to be quite tightly fastened.

Both types of fittings have advantages and disadvantages over the other: compression fittings are easier to use than solder fittings and it is simple to make a reliable seal. The solder join, on the other hand, can cope better with pipe movement, is sturdy and will last for years.

Both fitting types are available in a variety of bends, angles, cross overs and more, although ball-o-stop valves and taps are usually limited to compression-type fittings.

Now that you know what you need and how to use it, we hope that you’ve got the confidence to tackle that plumbing job yourself. All it takes is a bit of practice and planning, and your DIY partner – Builders.