Solder copper pipes: First timer with no leaks!

One way of connecting pipes

Because I got radiators of all different sizes I had to make some modifications to my fittings. There are three main ways to make copper connections. To solder copper pipes, using compression fittings and using Push fit. When it came to upgrading the central heating I actually ended up using all three methods. If I was to do it again, I would stick to push fit because the technology has moved on since old school plumbers have had nightmares of plastic parts. I’ll elaborate on that decision in a later post!

Safety first!

Before picking up the blow torch, have a look at where you will require to solder copper pipes. Some of my modifications were to existing pipes in between joists. Joists are of course made out of fires best friend: wood. This meant a lot of my preparation was securing the area and ensuring I wasn’t going to light the house up. When reading into dos and dont’s, I found horror stories of sites being engulfed due to lit embers starting a fire after the tradesmen left the property!

Make the connections at the workstation

If you’re able to, make the soldered connections on a workstation prior to fitting them under the flooring. This means you don’t have to work around cramped angles and you can work in an open environment with visuals to ensure you know where the heat is going.

Heat dissipation

If like me you want to make mods to an existing system, you can’t simply take it all out. What I did for some of these connections was to shield the wood work around me with scrap metal. The recommendation is to also use a soldering matt. My only concern was due to the size of these matts I didn’t feel 100% safe using only this as the heat barrier. When combined with scrap metal, I felt that it was truly insulating the work space.

Water

Another tip I found online was to have a bucket of water on standby. In case the worst happens and you catch something on fire, the last thing you want to do it leave it and run for the closest water source! By having this at hand you can deal with anything that may call for it. In addition to the bucket of water, you can have a damp cloth in it and wipe down the wood surrounding the pipes so that it’s too damp to actually catch alight.

Other than fire, what else can go wrong?

The main faff with soldered fittings is that if you don’t get a water tight seal. Once you’ve confirmed water is leaking out, you need to drain the system again. It’s not too hard to disassemble the fitting, albeit messy. But good luck trying to fix the mistake. Solder will not work if there’s any bit of water left over in the pipe! I’ve read of some old school methods plumbers have used including shoving bread up a pipe to absorb the water! It’s in your best interest to make sure it works right the first time. A compression fitting can be tightened. A push fit can be plugged back in.

Yorkshire fittings

Preparation is key

It’s the main reason I attribute to having zero leaks when I first repressurised the system. Whether it came to brand new fittings or refurbishing old pipes, to solder copper pipes they should end up looking the same before you start.

These are two examples of pipes I was working with

Solder copper pipe steps

Cutting the pipe

If you need to cut pipes, get a dedicated pipe cutter. I have cut pipes with hacksaws before and getting a clean cut is a nightmare. You also need to deburr your cut. Here is a good visualisation of what happens if you don’t deburr, much better than an explanation over text!

Remove dirt and paint

You can’t ensure a watertight seal when the surface has paint and other buildup on it. To remove the paint and dirt you need the copper to look brand new again. Using a mesh like this takes off all that paint and grime to start from a good base.

If you’re using new pipes you also need to do this. The smooth copper needs to have a rough surface for the flux to work. Once cleaned remove all dust trace.

Apply flux

I won’t get into the chemistry here. But you need flex on the edge of the pipe fittings where solder will meet. Without flux the solder cannot move up the pipe and will leave areas exposed for water ingress. You can apply too much as well! Too much flux will just burn off and compromise the fitting, also corroding it. You need to make sure there is enough covering the whole circumference and the copper isn’t bare.

This needs to be applied on with some sort of brush or tool. It’s nasty stuff you don’t want to get on your hands!

Connect the parts

Important thing to note here, if you have multiple connections on one fitting, you need to put these all in place. You can’t sequentially connect one pipe, join it and then add another. The heat on one side of the Yorkshire fitting will heat the solder in the rest of the fitting.

Once you’ve connected all the parts necessary you’re ready to solder copper pipes.

Heat it up!

You need a propane gas tank with a trigger. You can also use MAPP gas which reaches higher temperatures. This would enable you to solder copper pipes faster. For the one off DIYer propane is more than adequate, if you were to take up plumbing full time then MAPP would be worth taking up. As I was quite nervous doing this the first time I actually preferred using the slower variant.

When heating the part, you want to aim the tip of the brighter blue inner flame onto the fitting. This is the hottest part of the full flame. You need to aim the flame at the overall fitting and not just the connection. This will help even the heat spread and makes sure the solder is evenly heated and distributed. The copper will start to change colour and you’ll start seeing solder appear. As soon as you see a ring of solder appear at the end of the fitting you can remove it from heat. If you overdo this then you risk burning the solder out of the fitting.

Cool it!

You don’t need to actively cool it. In fact if you do, you can risk cracking the solder inside if the temperature differential is too quick. Just be patient and wait for it to come down on it’s own.

Clean it

If there is any excess flux around your pipes, now is the time to clean it off with a damp cloth. The problem with having excess flux left on the pipes is that it can corrode the pipes if left on. That should be it! Hopefully when you test the system there should be no leaks when you come to solder copper pipes.