CH system, copper v's plastic piping

ChrisR · 27 Jul 2006

I don't mind plastic pipe too much though it's nearly always badly installed on the ground floor, due to the difficulty of clipping insulated pipe. So it goes uninsulated or scuds about in the grot on the ground below the house. Then it often comes up at a wierd angle to strain a joint. If (as I thnk ChrisH is saying) you bend/add to the copper rad tail you can make life easy for the plastic

What's the horizontal clipping distance for 15mm hep pipe - got a feeling it's 300mm and pex is 600.

I also prefer compression to push-fit, I don't trust the O rings long term (in those strained joints) and have seen too many leaks.

chrishutt · 27 Jul 2006

ChrisR said:
What's the horizontal clipping distance for 15mm hep pipe - got a feeling it's 300mm and pex is 600.

That's really only applicable for heating pipe where it gets very soft. Cold water supplies don't need anything like that amount of clipping. One way of supporting long straightish runs is to stick the 15mm down the inside of some cheap overflow or plastic electrical conduit (20mm OD, 16mm bore, neat fit). Also gives extra protection against gnawing!

plumberstool · 27 Jul 2006

been plumbing since 1976, out and out brought up on copper and copper only, just done a farmhouse conversion, fully fitted out with polyplumb, tested it as required, had one problem where i tried to save a fitting and did not push fitting on properly, so one number fitting in a five bathroom and kitchen not bad , we also could have not got the access with copper as we have with the plastic, also installed 2400 mts of plastic underfloor heating, not one problem, but then used it on an extension job, buider reported leak kept showing found it to be a scratch on pipe which made a groove and would not seal properly, if this was copper solder would have sealed this. but we must move forwards and surely the manufacturers would not spend fortunes on a product if it was going to cause problems on a massive scale. but if so there will be plenty of work for us copper trained plumbers. just a thought how many of you would not touch a combi boiler when they first came out, look at their rise in the heating market as i said is it time to move forwards

doitall · 27 Jul 2006

plumberstool said:
as i said is it time to move forwards

Move forward or lower the standards

.

Because thats whats happening like it or not, the new kids on the block are rubbish as far as quality is concerned.

Onetap · 28 Jul 2006

tartansand said:
The last claims that barrier plastic pipe still allows oxygen to penetrate plus the push fit joints also allow oxygen into the system. Reckons he's seen plastic piped systems where the rads have corroded within 5 years or less. He proposes using pipe which is a combination of plastic outer and copper inner. He called it some name but can't remember it and I can't find anytrhing on the web relating to it.

The pipe is PEX-Al-PEX.
PEX is cross-linked polyethylene, preferable to polybutylene, IMHO.
PEX-AL-PEX is an aluminium tube sandwiched in PEX, as the name suggests. The aluminium is the oxygen barrier and also allows the tube to be bent and retain the bent shape. PEX alone will try to straighten itself, it's a pig to get it to stay put if it's not fixed as you unroll it.

The oxygen barrier limits the oxygen absorption through the wall of the tube. You will still get some oxygen absorption. In fact you will get some oxygen absortion with any heating system. The oxygen will corrode the inner surface of the radiators, IF (big if here) it's not prevented. It is prevented by the use of chemical inhibitors which contain a component called an oxygen scavenger. This chemical combines with the oxygen before the oxygen corrodes anything.

In commercial system you would measure the concentration of the oxygen scavenger with the appropriate test kit. The depletion of the level of the oxygen scavenger would indicate the amount of oxygen entering the system. Domestic inhibitor makers won't tell what chemicals they use, so most people just bung in a fresh bottle every couple of years or when they drain it.

tartansand said:
Any truth in the last one's claims?
If do, will inhibitor prevent the corrosion

Yes, a little, and yes. He's got half the facts.

doitall · 28 Jul 2006

Unipipe is the name Onetap, but no doubt others make a similar stuff.

A competely different product to pushfit, and 100% better.

Nige F · 28 Jul 2006

plumberstool said:
been plumbing since 1976,

does that include apprentice time ?........started mine in 72

tartansand · 28 Jul 2006

My thanks to all contributors.
You've helped make a muddy picture a little clearer!

corgiman · 28 Jul 2006

sheesh

bet you lot got upset when they banned the use of lead

"lead was good enough when i was a lad but get on with this new fangled copper and its end feed solder fittings its bound to fail"

At the end of the day Poly is easy to install and if done right (like copper, cos if you aint done that right it will leak) will do you a treat for ages.

The choice tartan is yours to make

By the way do you know what the collective noun for a group of plumbers is?.......................

A quarrel

chrishutt · 28 Jul 2006

corgiman said:
By the way do you know what the collective noun for a group of plumbers is?.......................A quarrel

Are you sure it's not a flood, or a flush?

corgiman · 29 Jul 2006

could be

a row
a bi tch
a whinge
a whine
a stubborn
a arrogance (no wait thats for sparkies)

I could go on

but for the sake of everyone losing the will to live I wont

ChrisR · 29 Jul 2006

Could it be an
an ahbut
an objection
or
a
ssssththththth?

Onetap · 29 Jul 2006

corgiman said:
could be

a arrogance (no wait thats for sparkies)

No, no, Corgiman. It's a shower of sparks. Or is it a shower of plumbers?

Unipipe is the Wirsbo/Uponor version of PEX. Rehau also make a crimp fittings; they do an installers course, during which they test a 15mm joint to destruction with a tension machine. I think it fails at something like 400 lb force. It's the PEX that eventually fails, not the joint. If there's that much force on one of your joints, I think you probably haven't followed the manufacturer's instructions.

http://www.heatinghelp.com/newsletter.cfm?Id=18

Most/all of the manufacturers offer PEX-AL-PEX, Speedfit is PEX-AL-PEX. I think Rehau and Wirsbo/Unipipe are the only ones who offer PEX-A.

ChrisR · 29 Jul 2006

I'm sure you're adrift there, onetap. The aluminium layer makes the pipe a different animal - it stays bent where you put it, and they're not the same size as standard (ie 16, 20mm etc). The speedfit pex, and the other 15mm ones, don't have any aluminium in. The barrier layer in those is some other plastic.

doitall · 29 Jul 2006

ChrisR said:
I'm sure you're adrift there, onetap. The aluminium layer makes the pipe a different animal - it stays bent where you put it, and they're not the same size as standard (ie 16, 20mm etc). The speedfit pex, and the other 15mm ones, don't have any aluminium in. The barrier layer in those is some other plastic.

Correct Chris, Unipipe is far superior to any of the plastic barrier pipes.

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CH system, copper v's plastic piping

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