1: Start off with LEAD solder, not lead-free. It has a lower melting point and is more ductile. Toolstation et al sell it for plumbing. It is not suitable for potable water, although there must be many millions of joints made all over the planet using it.
1a: Don't even think about butane (from the DIY sheds). Use propane, or if bold MAPP gas (hotter), with a decent torch head - Rothenberger are excellent, so are Primus Sievert (although recently not popular). Both the latter gases will boil off any water drips in pipes you cannot fully dry beforehand, but butane will not, meaning your joint stubbornly stays at 100 C, and the solder doesn't melt properly, and you get a failing joint or none at all.
2: I recommend LaCo brand flux. I've used it for four decades. You don't need much more than a smear on both surfaces (and dip about 3/4" of the solder wire before applying it to the joint. It does sting on the fingers though - I keep a jam jar of water and a roll paper towel handy, as it's just too convenient to use a pinkie to get flux into the fittings. Yes, I know of "flux brushes" too!
3. If you can, clean with wire wool. There are stiff wire brushes, and even perforated emery cloths available, and branded as pipe cleaning tools: they work, but unless the pipe and fittings are really badly oxidised or corroded, they are unnecessary and leave nasty scratches - you want reasonable smoothness for good capilliary action, taking the solder right into the joint.
4. Get a pipe cutter. This saves time, and makes a far neater cut than any hacksaw, Dremel tool, Goldfinger laser or whatever. I like the "Pipeslice" type, but the traditional ones that advance the cutting disc with a screwthread (adjusted by hand) work just as well. keep it clean and slightly lubricated - the flux will deal with tiny traces of oil, but the device will cut better. They are more awkward and won't work in confined spaces (Pipeslices will), but one size will do several sizes of pipe.
Pipeslice type:
Traditional type:
I have and use both styles above. The lower one uses the "tighten a little, twist a bit, repeat" method.
The fold-out "spike" in the side is to de-burr the ends of the pipe after the cut. Pipeslices usually leave a neater cut for some reason, so I rarely bother when using them, unless non-turbulent flow is really important. If you do attempt cutting with a hacksaw, your fingers only have you to blame, and you will probably need a fairly fine cut rat's tail file to clean up afterwards. The good news is that fittings don't really need a perfectly square end to the pipe, but don't be silly about it, and you must remove all swarf from inside the pipe, or expect valves and taps, etc. to leak or fail.
5. Learn on end-feed fittings - the ones with NO solder pre-fitted into them. This is for several reasons: (a.) you'll get more confidence - it's a lot easier than it looks, (b.) they are cheaper than any other sort of joint, (c) you can even do one end of the fitting and the second (or third) connection separately. You will also get a feel for how much solder you need to apply.
6. Heat the pipe(s) first and mostly, NOT the fitting. Heat is transferred to the fitting very well by copper, but if you heat the fitting you will likely overheat it and burn away the flux, giving a "dry" joint, i.e. a potential failure. Just play the flame over the fitting for a couple of seconds occasionally while you mostly heat the pipe(s), say a 1:4 ratio in time or even smaller than that.
7. Turn your blowlamp down fairly low, at least to start with. With a Rothenberger head running propane, I struggle to get it as cool as I'd like (yet still keep it lit). Low heat gives you time to get everything just so. You will see the flux clean the pipe and fizz a bit, after that happens count to 5 slowly, take the blowlamp away for a sec, then wipe the end of the solder around the end of the fitting to see if it leaves a silver trail behind - if so, you are nearly there - little more heat and solder together will make the joint. Wipe the solder roughly 2/3 - 3/4 round the pipe. gravity and capilliary action will close up the solder ring.
8. You almost certainly need much less solder than you think you do (beginner's mistake), but you do need heat - once the solder liquefies and flows, keep heating for a few seconds longer. It's partly to ensure any flux residue clears from the joint, leaving only solder all round. The solder won't all fall to the bottom side under gravity - don't worry about horizontal joints, and when doing the underside of vertical ones, relax - the solder will flow up to where it needs to be.
8a. Why does flux residue matter? If you use a lot of flux and solder, but insufficient heat, you can make joints that fail. It's rare but you get an incomplete ring of solder, with a narrow plug of burned flux filling the gap. Flux is intended to be water soluble, so it can be cleaned from the inside of the pipework. So you make your joints and check them and they are fine. two days after you fill the system with water you have a pinhole leak! But don't be fooled: "pinhole" is a comic term used to make the plumber really embarrassed as they stand there with mop and bucket - it will leak a LOT of water under pressure!
8b: Buy an inspection mirror, and use a small torch (I mostly use a bike LED headlight). Wipe the finished joint clean with a damp cloth then have a good look. As long as you are sure you can see a complete ring of solder, it's probably fine. Rectangular inspection mirrors are probably more useful than round ones, incidentally - I often get frustrated as I can't
quite see the bit of the joint I need to. But relax - if you experiment by doing just one end of a straight capilliary coupler you will easily see how well the solder "wicks" right down to the end of the pipe in the fitting - it's a lot more robust than you may think initially.
9: Neat plumbing starts with neat pencil lines on the wall marking the centrelines of the pipes, followed by pipe clips. Dry-fit stuff together before doing anything else, to ensure you don't wrongly measure something then embarrass yourself. DAMHIKT!
10: one of the best things about end-feed fittings (apart from neatness) is the ability to pre-assemble sections of pipework. I use an old school-chemistry retort stand and clamps to hold stuff together at the easiest angle for soldering, and make the joints out in the back yard (anywhere convenient). home-made wooden clamps would do just as well (15mm and 22mm are outside diameters, for the purpose of clamp making). This also lets you wash off, wash out, and generally clean the assembled section before you fit it. As I said, you can solder any two ends of a Tee-piece, thus ensuring those joints are good, before doing the third end. It takes a little practice, but heating mostly the pipe and rarely the fitting gets it done well and neatly.
11: the time will come when you have to solder a pipe that has to be clipped in place first. Copper conducts heat really well, and you can melt pipe clips if incautious. I try to avoid joints closer than around 3" from clips, but in the extreme, GENTLY clamp a mole wrench between fitting and clip, next to the clip, to act as a heatsink. Works a treat.
12: This is the next step: pipe bending lets you do stuff for which no fittings are available, and gives quieter pipework as bends are radiused. It's neat if it's done carefully. You have a choice of springs or pipe benders for 15 and 22mm. Both stop the tube collapsing. Springs go inside the pipe, benders fit onto it. Sizes smaller than 15mm have springs that go over the pipe. When using springs, bend slightly more than the angle you need, then back to the correct bend. This frees the spring from the pipe (otherwise good luck with getting it out/off!). I prefer a pipe bender for 15 & 22mm, and external springs for smaller pipe sizes (small benders are usually rubbish in my experience). As supplied, fresh tube is slightly work-hardened. Copper anneals very easily though, so heat the length you intend to bend with your blowlamp and let it cool, then you'll find the bend is far easier, and probably neater. Don't go nuts, for 15mm, the tightest bend you can reasonably make is probably about 60-80mm radius. Too tight risks the pipe wrinkling or collapsing (good luck recovering the spring at that point!). It's not an issue with a pipe bender, but they do need lubrication and to be kept clean to avoid wrinkles on the inside of the bend. Also protect the straight former that comes with the tool - damage to the edges of it also causes wrinkles.
13: when we went metric way back in the 1970s, 15mm replaced 1/2" pipe and 22mm replaced 3/4". But the way of measuring changed, too: 1/2" is the
]inside diameter of the pipe, 15mm is the
outside diameter. Same with 3/4" and 22mm, but 22mm is significantly bigger and the difference is obvious. With 15mm and 1/2" it is VERY, annoyingly, close (1/2" OD is 15.88mm I think). Using compression fittings ("Conex", "olives", "spannered", whatever), you can just about fit either sort of pipe in (if the olives compress properly), but you cannot do this with soldered joints - they can sometimes be forced together, but 15mm is too loose in an old fitting and 1/2" too tight in a modern one. The solution is to use emery cloth to reduce the outside diameter of 1/2" pipe until it fits. It takes a while!
Why mention this at all? Recently, I was surprised to find a length of 1/2" pipe had been used in our solar heating installation, installed in the late 1990s. I think the plumber, working in our attic, had found a gash length of 1/2" pipe I was keeping (for a very rainy day), and used it. All the joints were compression fittings, so it didn't matter back then. I expect 1/2" in old properties, but I thought I'd long ago removed the last of it in this house, and never expected it in a recent installation! If in doubt measure, it rather than getting stuck in with the flux etc. only to find it won't fit!
Way too much info as usual. But some might be helpful...
E.
PS: I am old-fashioned. I won't have plastic pipework in the house, other than for waste pipes. That may mark me out as a Luddite, but I have seen quite a few leaks (elsewhere) when it hasn't been done properly. Your mileage, etc.
