New build Plumbing

The plumber my daughter employed for installing central heating and reversing the hot water flow used copper pipes and copper pushfit, with occasional soldering.

I expect they use pushfit because it's quicker. There may also be a ban on hot work on site to reduce paperwork, especially where stud walls are involved.

There's also copper pressfit. About as quick as pushfit but more compact in boiler rooms etc. Also in larger sizes (28mm etc) pushfit gets expensive.

Theo

No; if it's your build. do what you like. But I dare say some building sites insist on no "hot works" for RAMS/insurance reasons ...

I've used a few copper pushfit at radiator valve elbows, mainly for appearance as they're on show. Seem unlikely but so far they've held.

They look good but IIUC they do need an expensive tool (£1000+) for installation, and a fair bit of space around the fitting to use it.

That said, if I could solder I would. Looks better, cheaper, and at least seems as if it would be more reliable than push or press fit.

They have a long rated life like 50 years.

There are manual pressfit tools, basically a hand pumped hydraulic press, for ~£50 on Aliexpress, and battery ones for ~£300. But you do need the space for access. For a pro on a building site pressfit is quicker, the space is often still open (no plasterboard yet) and the official tool price is not a problem.

If you're fixing a central heating pipe under the floorboards, hot work is more risky. Then other methods are more attractive.

The other thing about solder is things need to be perfectly dry. In a new build they are, but in a DIY scenario it may be more annoying to achieve.

I've been working on some 50 year old soldered copper this week. The copper looks sound, the solder joints have oxidised to a manky green, but otherwise it appears to be in good order. I'm not sure whether I'd trust the EPDM seals in push/pressfit to be good at that point - and 'tear apart the bathroom to get at the leaking joint' is not a nice thing to have to do at any age. Even if you redo the bathroom more frequently, are you going to be remaking every single joint?

If not soldered, compression at least has metal to metal contact so there should be no dependence on a rubber seal.

(To avoid hot work inside, I've been assembling and soldering my pipework outside and then compression-fitting it to the existing pipes. That way I have only a handful of compression joints and the rest is soldered. Solder ring fittings plus a dab of extra solder for insurance purposes.)

Theo

On low end house builds it will be plastic, as it is cheap, easy to do, can be ran in non-straight lines and pretty much idiot proof connections. It is s**te. On better quality new builds, it will be crimped copper connections. Far better quality, far more expensive, and look better. Yes, gas torches have been banned from many sites now. It's mainly insurance based, my own liability insurance forbids the use of heat guns/gas torches in a premises. Even grinders are now banned inside on many sites. The only people using soldered pipe connections now are small companies who are stuck in their ways, and their insurance still allows gas torches for soldering. The way forward is definitely crimped copper, and yes, it can be used for gas.

A plumber I was getting quotes from says he has moved to "multilayer composite pipe (MLCP) " from normal PEX as a result of working on new builds. Sounds good stuff but I would suspect diy modifications or even work by another plumber on it later may be problematic as non-standard ?

I believe the "manky green oxide" might be caused by the residue from the flux not being cleaned off ?

(not that its of any practical use whatever :-\ )

Possibly, or maybe a reaction product of tin and/or copper in the presence of water? (mains water feed so naturally colder than ambient and attracts condensation)

I should clean it up, but I imagine whatever acidic properties it once had have gone over the past 50 years.

Theo

As I said .... of any practical use whatever

Yes. Its something like copper carbonate.

Nope.