Green Building Forum - Plastic or copper?

Plastic or copper?

kristeva — Sun, 28 Aug 2022 08:36:24 +0100

Hi all

I'll be plumbing the bathroom soon and just wanted to canvass thoughts on the copper v plastic conundrum.

I've got a number options, push fit, copper and push fit joints, compression & copper, or even copper and solder although I'm not greatly experienced and bit nervous waving a blow torch around an old house in tight spaces!

All have there pros and cons, notching is less kind to joists, so many scare stories about plastic fittings (rodent attack / leaks, etc), if I use copper I'll have to get a pipe bender, more unseen joints with push fit.

Cheers

P

Plastic or copper?

WillInAberdeen — Sun, 28 Aug 2022 09:57:42 +0100

As a very amateur plumber, I sometimes find I assemble pipework but then have to disassemble it, eg to pop a fitting over the other end of the pipe, or to adjust the alignment. Push fit allows me to get away with that, and bendy plastic pipe requires less accuracy anyway.

The skill that pro plumbers have with copper pipe is partly the solder joints, but more importantly "getting everything right first time" as it is very difficult to disassemble if something turns out 3mm too long.

"Bathroom company" fitters seem to use pushfit plastic.

I actually find the waste pipes are the most difficult.

Plastic or copper?

Peter_in_Hungary — Sun, 28 Aug 2022 10:38:17 +0100

The por. plumbers dry fit a section of pipework together to a point where no further changes will be needed (including pipe clips) and then solder the whole lot in one go.
Soldering pipework is quite easy (after a bit of practice) the key is to properly clean both pipe and fittings before attempting any soldering. I use a fine grade wire wool to clean the pipe before fitting and soldering.
I now use a combined flux and solder paste e.g. Rosol 3 and then add a bit more solder when I see the solder contained within the flux appear at the joint end.
When soldering pipework use a soldering mat behind the joint to protect the surface.e.g.
https://www.screwfix.com/p/rothenberger-soldering-mat-195-x-250mm/54910
Plastic pipework will sag over time so not the best if it is on show for more than short lengths otherwise OK. I avoid push fit joints in locations that can't be seen.

Plastic or copper?

djh — Sun, 28 Aug 2022 10:51:23 +0100

We used plastic plumbing for all the long runs, so there are no joints hidden away. The plumber I used put short copper tails on the plastic just before we attached the flexible tails of the taps. There's also copper at the start of the plumbing, where's there's a kind of home-made manifold of isolation valves at the head end of all the long runs. Wastes are plastic everywhere, starting with push-fit and transitioning to solvent weld for the more serious stuff.

Plastic or copper?

Jeff B — Sun, 28 Aug 2022 13:20:03 +0100

Copper every time for me.

As Peter says, soldered joints are easy after a bit of practice. In my situation it was a case of "necessity being the mother of invention". I bought a house where the seller must have known there was a problem with leaks from C/H pipework taking place within the concrete screed but obviously said nothing. The cash deposit on the house meant we had little reserve funds to pay a plumber so we ended up re-piping the whole C/H system ourselves! In certain situations I will use compression fittings and always, always put in lots of service valves which plumbers seem very reluctant to do. They are so cheap and will make the job of isolating parts of any plumbing installation so much easier for maintenance purposes.

Plastic or copper?

djh — Sun, 28 Aug 2022 13:32:03 +0100

Posted By: Jeff Balways, always put in lots of service valves which plumbers seem very reluctant to do

I get the impression that omitting isolation valves is yet another British disease, but maybe I'm too kind to our continental neighbours? But anyway, they're definitely a good idea.

Plastic or copper?

philedge — Sun, 28 Aug 2022 16:55:22 +0100

For service valves always buy branded ones as youve got more chance of them not leaking a decade after install when you come to use them.

For soldering the 2 important things are clean/polished fitting and pipe end as PiH has mentioned. The second is dont play the flame on the joint. Play the cone of the flame on the pipe or centre of the fitting just to the side of the join and let the heat travel to the join.

An old 5ltr paint tin lid makes a good heat shield

Plastic or copper?

Cliff Pope — Sun, 28 Aug 2022 18:30:45 +0100

I agree about the usefulness of service valves, but have reservations about the kind that have a little rotating ball turned with a screwdriver. In my (bitter) experience they are liable to leak the first time you use one because the exposed surface of the ball has tarnished in the meantime and damages the seal when turned.
Also they do impose a restriction in the flow, which may not matter but can make them noisy as water whistles through.

The best I think are proper gate valves, but they are obviously a bit unsightly.

Plastic or copper?

Peter_in_Hungary — Sun, 28 Aug 2022 19:27:58 +0100

Posted By: philedgeAn old 5ltr paint tin lid makes a good heat shield

With limitations, it will smell wonderful if there is ANY paint left on it and perhaps more importantly enough heat can be radiated from the back to blister any paint too close whereas the soldering mat that I use the back never gets too hot to touch.

Plastic or copper?

tony — Sun, 28 Aug 2022 19:39:48 +0100

I like plastic pipes and fittings

Plastic or copper?

kristeva — Sun, 28 Aug 2022 22:02:21 +0100

thanks for all the comments, as I anticipated a mixture of opinions.

Plastic or copper?

Artiglio — Sun, 28 Aug 2022 22:08:38 +0100

If thereâ€™s a chance of mice/rats/squirrels then copper, if not then plastic is so much easier. Isolation valves are handy but the â€œballofixâ€ type will likely leak when used 5 years later. Proper lever valves at suitable locations ( to isolate chunks of the system rather than every tap etc) you can soon cap a connection if you need to go and get a fitting etc.

Plastic or copper?

revor — Mon, 29 Aug 2022 08:59:38 +0100

I use both, plastic to run pipes through awkward areas and to avoid joints underfloor or in partitions etc. I like to have easy access to every joint. For pipe runs involving heating systems to and from cylinders boiler etc I prefer copper solder joints less bulky than compression fittings. When I was doing our build insurance conditions stipulated that I could not do flame work in the house so assembled pipework in situ and marked up the positions with pencil reassembled in workshop and did flamework there. Assembling then in the house with compression fittings. Most H&C pipes run from a manifold in the "plant room" negating use of local ballofix valves.

Plastic or copper?

Mike1 — Mon, 29 Aug 2022 18:09:15 +0100

Posted By: philedgeFor service valves always buy branded ones as youve got more chance of them not leaking a decade after install when you come to use them.

+1. However a good idea to turn them each year to keep them usable.

Posted By: revorI use both, plastic to run pipes through awkward areas and to avoid joints underfloor or in partitions etc. I like to have easy access to every joint. For pipe runs involving heating systems to and from cylinders boiler etc I prefer copper solder joints less bulky than compression fittings.

More-or-less what I do too.

Posted By: djhThe plumber I used put short copper tails on the plastic just before we attached the flexible tails of the taps.

Avoid flexible pipes wherever possible, and only use them where you can easily get at them to replace them. They have a limited lifespan and can (and do) burst after 10-20 years.

Plastic or copper?

wholaa — Wed, 31 Aug 2022 05:36:23 +0100

Copper is meant to require less energy to move water through. It does require careful design to minimise bends, which are more erosion-prone and energy costing.

Plastic or copper?

borpin — Wed, 31 Aug 2022 06:59:52 +0100

I'm definitely a plastic advocate, but I will often use the Pegler/Yorkshire Tectite fittings (the pro ones).

I use flexible tails with an integrated valve and push fit.

You can easily just use 10mm to basins and toilets.

If you have a risk of mice, beware. They love plastic pipe!

Stand the pipes off the wall more than the normal clips so you can get thick insulation on. Round the tank etc, again, think of insulation - plumbers leave the bare minimum of a gap often making insulation problematic. I use a double layer of black EPDM insulation so need a bigger gap around each pipe.

I have seen a growing used of crimped copper fittings.

Plastic or copper?

Cliff Pope — Wed, 31 Aug 2022 08:53:02 +0100

Posted By: borpin

If you have a risk of mice, beware. They love plastic pipe!

.

And pipe insulation! They seem to eat the plastic stuff and drag the fabric back to their nests for bedding.

Plastic or copper?

Simon Still — Wed, 31 Aug 2022 09:41:36 +0100

Posted By: Artiglio Isolation valves are handy but the â€œballofixâ€ type will likely leak when used 5 years later. Proper lever valves at suitable locations ( to isolate chunks of the system rather than every tap etc) you can soon cap a connection if you need to go and get a fitting etc.

This has always been my experience - crappy isolation valves that don't actually work and need to be replaced at the same time as the thing you're trying to isolate. Turning off the whole system briefly is little more effort and you can cap a pipe with a push fit end if it needs to stay off for a while

I used central manifolds and plastic everywhere (but none of it is visible). Whenever the manifolds are exposed (they're behind a built in bookcase) I turn them all off and on, but I'm pretty convinced they'll stiffen up to be useless, or leak, by the time I actually need to use them 'in anger'.

Plastic or copper?

Peter_in_Hungary — Wed, 31 Aug 2022 09:47:24 +0100

When we talk of plastic pipes can I assume we are talking plastic and not pex?

Plastic or copper?

Mike1 — Wed, 31 Aug 2022 13:17:11 +0100

Posted By: Peter_in_HungaryWhen we talk of plastic pipes can I assume we are talking plastic and not pex?

PEX is a plastic (cross-linked polyethylene).

Plastic or copper?

Peter_in_Hungary — Wed, 31 Aug 2022 14:15:29 +0100

And then there is alpex

Plastic or copper?

WillInAberdeen — Wed, 31 Aug 2022 15:18:45 +0100

We haven't mentioned Supplementary Bonding. Some electricians IMI insist on there being green/yellow electrical connections clamped to anything in the bathroom which is not visibly piped in plastic (eg where a copper tail above floor level, transitions to plastic below the floor, where it cannot be seen by the electrician).

One sparky in particular was very awkward about signing off some completely unrelated work elsewhere in the house, because of the missing green/yellow clamps in the bathroom.

There are exemptions in the wiring regs where supplementary bonding is not required to copper-piped fittings, but some expert interpretation is required and the sparky might find it easier to insist on you bonding everything. It's one of the areas of the wiring regs where sparkies like to disagree.

If you plumb in plastic then the issue doesn't arrise. Worth avoiding a mix of plastic and copper I think.

Plastic or copper?

Mike1 — Wed, 31 Aug 2022 16:50:06 +0100

Posted By: WillInAberdeenWe haven't mentioned Supplementary Bonding.

Since the 18th edition of the standard, supplementary bonding can be omitted in a bath or shower room if the _whole-house_ electrical installation meets certain criteria - main protective bonding is in place everywhere _and_ there are 30mA RCDs on all circuits _and_ all extraneous-conductive parts are bonded.

See
https://electrical.theiet.org/wiring-matters/years/2019/77-september-2019/bs-76712018-frequently-asked-questions/

https://electrical.theiet.org/wiring-matters/years/2019/76-july-2019/protective-bonding-habits/

Plastic or copper?

WillInAberdeen — Wed, 31 Aug 2022 22:17:25 +0100

Yep, the issue for the sparky I mentioned was that he could only see copper pipework tails in the bathroom without any supplementary bonding, and copper pipe near the mains water supply without main bonding. I knew it was all plastic pipe below the floor and the blue plastic supply wasn't extraneous-conductive, but that wasn't visible to him without ripping up the floor, so he assumed the worst case.

If doing another bathroom or kitchen, I'd bring the plastic pipe above floor level to avoid causing anyone doubts.

Plastic or copper?

tony — Wed, 31 Aug 2022 22:22:22 +0100

We once earth bonded our electricians knife, fork and spoon together at our Christmas meal

Plastic or copper?

WillInAberdeen — Wed, 07 Sep 2022 22:16:00 +0100

Posted By: Simon StillPosted By: Artiglio Isolation valves are handy but the â€œballofixâ€ type will likely leak when used 5 years later. Proper lever valves at suitable locations ( to isolate chunks of the system rather than every tap etc) you can soon cap a connection if you need to go and get a fitting etc.
This has always been my experience - crappy isolation valves that don't actually work and need to be replaced at the same time as the thing you're trying to isolate. Turning off the whole system briefly is little more effort and you can cap a pipe with a push fit end if it needs to stay off for a while

So exactly that happened tonight, after a leak in the washing machine. The isolation ballvalve was jammed and useless. But the house mains stop valve was only six feet further away, and I know it works because I use it whenever we go away. It was so little effort to turn off the house supply, disconnect and cap the washing machine feed, that I'm not going to bother trying to remove the seized isolation valve to replace it.

Plastic or copper?

LF — Fri, 09 Sep 2022 12:45:05 +0100

Will, I have suffered the same with crap isolation valves on taps and appliances and agree with your sentiments.

With no cold header tanks and only combi mains hot water it is simple to drain everything.

You have to fit the ball valves the right way around for washing machines or they leak as well.
They are jointed so can leak on fitting where they join to the pipe

I plan to put an second isolation on main cold feed when we start house refurb, one of the leak remote shut off switches.

Plastic or copper?

wookey — Fri, 07 Oct 2022 12:36:18 +0100

I've mostly switched to plastic from copper. And would also echo the comments on cheap ball valves being almost as much of a pain as they are useful, over the long term. Spend some money on decent ones.

The best use of plastic pipe is if you can thread it all without joints. Ideally the modern manifold-style plumbing where you know there are no joints in each run.

To be fair I've not done this (because it's usually only practical in new-build) and just do conventional plumbing with corners and fittings (JG) and have not had any joint failures, but then I've only been in this house for 17 years. My oldest (Hep2O) piping is in the previous house and must be ~29 years old now. I could go round sometime and ask if it's leaked yet :-) It was fine for the 12 years it was installed there. Plastic is just less faff than bending and soldering, and is easy to change around later.