PEX-AL-PEX pipes

[kan.izh]

Hi all,

I need to reroute few hot/cold water and heating pipes in my house.

At the moment all pipes are copper. For a small DIY job I see that a composite (plastic+metal) PEX-AL-PEX pipe is much easier to use - the ads look very convincing - easy to bend, easy to fit, require less joints, etc.

However, I wonder why is it so unpopular? Is it just something new and have not widely adopted yet or is it bad alternative? What do ads keep in secret?

 

[SandyLyon]

Most Multilayer pipes are European sizes (16mm, 20mm and 25mm) so you would need adaptors to UK sizes, most Multilayer systems are designed to be used with "crimp" type fittings (some do compression and push fit).
Therefore you would be adding additional cost to the project by the extra adaptors and hiring or purchase of a crimping tool.
If you want to use a plastic system I would recommend using a Polybutylene pipe with pushfit fittings such as Hep2o

 

[kan.izh]

Yes, I think I would choose compression fittings, probably it would be more expensive but not noticeable, as I don't need many of them.
Also as I know there are different type of fittings, e.g. they could connect old copper pipe with the new pipe, so there is no extra adaptors.

As I heard plastic-only pipes are not applicable for heating, because they could conduct oxygen, and PEX-AL-PEX pipes are ok as aluminium layer protects against the oxygen. Is it true?

Another question I'm thinking about. Currently the copper pipes are all connected to ground by yellow-green earth wires. If I replace segment of a pipeline, do I need to connect wires somehow?

I still don't understand why composite pipes are not used in UK. Any ideas? Is it just tradition?

 

[SandyLyon]

Polybutylene Barrier pipe is fine with central heating as the chemical barrier prevents the ingress of oxygen into the system.
Read up on Earth bonding it may be possible to "bridge" the plastic with earth cable.
Multilayered pipe is widely used in the UK but more so in commercial / industrial sector where the price of large dia copper tube is astronomical.
As far as its use in domestic situations the main drawbacks are mixing euro and UK sizes as most fittings, showers, taps, valves etc are 1/2" / 15mm and cost.

 

[kan.izh]

Ok, thanks. I'll read about earth bonding.

That's the thing, I cannot have UK sizes for the pipe. Does commercial/industrial sector use Euro sizes? Or they don't care about mixing?

Internet says horrible things about PB pipes, e.g. http://www.propex.com/C_f_env_polybu.htm . So, I am convinced that it is a bad choice. Is it true?

 

[MJGas]

http://tectite.co.uk/En/FlexibleMetal

 

[kan.izh]

"Tectite Tube - World's first Flexible Metal Tube in 15 and 22mm." Wow, sounds promising, but as I see it could be a challenge to buy it as a non-trader for a small DIY project...