Plastic pipes, push fit vs copper

diystarter7

Hi
Silly question to some but grateful for an answer.
Do plastic pipes freeze as easily as copper, I doubt it. If I am correct, is they a big different, EG copper would certainly freeze in an area same tp and no lagging vs a plastic pipe in the same area no lagging, ie net to each other both cold water pipes

Thanks

ThisIsWeird

Plastic pipes are less likely to freeze in the first place as they are naturally better insulated (plastic wall being thicker and a less good conductor than copper), and are also less likely to burst when they do freeze (the fittings are often an exception - they are made of a harder, more brittle, thermoplastic, and can (do...) split along their side seams).

diystarter7

ThisIsWeird said:

Plastic pipes are less likely to freeze in the first place as they are naturally better insulated (plastic wall being thicker and a less good conductor than copper), and are also less likely to burst when they do freeze (the fittings are often an exception - they are made of a harder, more brittle, thermoplastic, and can (do...) split along their side seams).

As suspected and thanks for confirming.
Last question, the push-fit connector, if properly fitted, is still a weak point plastic to plastic and or plastic to copper?
Thanks in advance

grumbler

So, is it  plastic vs copper? What does push-fit have to do with this?

If water doesn't flow, plasitc pipes will freeze as easily as copper ones.

If water flows, plastic pipes can be marginally better because plastic is worse heat conductor than copper.

And my feeling is that plastic pipes (not waste ones) are less likely to burst when freezing. Don't take my word for it.

Section62

diystarter7 said:

Hi
Silly question to some but grateful for an answer.
Do plastic pipes freeze as easily as copper, I doubt it. If I am correct, is they a big different, EG copper would certainly freeze in an area same tp and no lagging vs a plastic pipe in the same area no lagging, ie net to each other both cold water pipes

Thanks

If a pipe is going to freeze then it will probably freeze whether it is plastic or copper.  Plastic has a marginally better thermal insulation performance, but not enough to make a  practical difference. (else it wouldn't be recommended to freeze food in plastic containers)

What does make a difference is that plastic push-fit fittings generally don't have the same mechanical strength compared to well-made soldered or compression joints.  So if the pipe does freeze, a push-fit joint is likely to be the place where the pipe fails first.

So if someone is intent on saving money by not using proper insultation on a pipe which is potentially exposed to freezing temperatures then there is possibly a marginal benefit by using copper and either soldered or compression fittings.

But it would make much more sense to spend money on decent pipe insulation, rather than speculating whether plastic pipe will perform better than copper.

diystarter7

grumbler said:

So, is it  plastic vs copper? What does push-fit have to do with this?

I'm a bit taken aback you asked.

https://www.professionalbuildingsupplies.co.uk/plumbing/can-you-use-push-fit-on-copper-pipes

Thanks for trying to help, appreciated it.

grumbler

Push-fit is not only for plastic pipes. And compression joints are not only for copper.

And there are push-fit fittings specially for copper pipes. Not sure if they work for plastic ones.

stuart45

The one above is really designed for DIY for copper pipes which can be seen. They look similar to a soldered joint. You can't get them in the plumbers merchants, but places like B&Q sell them.  You need a special tool to disconnect them.

diystarter7

Thanks all, I got all the info I need.

ThisIsWeird

diystarter7 said:

As suspected and thanks for confirming.
Last question, the push-fit connector, if properly fitted, is still a weak point plastic to plastic and or plastic to copper?
Thanks in advance

Push-fits are only weak points in general if not done correctly. But they are also more vulnerable to failing if frozen (I'm basing that on the first of its type - Bartol 'Acorn').

I don't recall ever having had a push-fit connection fail, either on copper or plastic pipe, provided it was done correctly. By 'correctly', I mean that there were no 'burrs' on the end of the pipes that could damage the O rings, no stupidly-deep grooves or scratches on the pipe surface, support inserts of the correct type were always used on the plastic pipe, the pipes were inserted the correct - full - depth, and the fittings were undamaged (they can be reused, but you best know their provenance).

I have seen things go wrong - including for me - when one of the above was not observed, always 'accidentally'...

I trust you are not considering using plastic pipes and fittings in order to save on lagging? But, if I had a situation where the freezing of pipes was a known risk, or the consequences of it happening serious (eg pipes buried in the ground, or in a loft where water damage would be more serious), then I would choose plastic over copper every single day, but obviously also lag it. I repeat - it is significantly less likely to freeze in the first place, and less likely to fail should it freeze. Plastic is a much better insulator than copper*, and the wall thickness must be at least twice that of copper, perhaps x 3?

* hold a 6" piece of plastic pipe in one hand, and a matching piece of copper in the other. Stick both ends in a blow torch flame.

diystarter7

ThisIsWeird said:

diystarter7 said:

As suspected and thanks for confirming.
Last question, the push-fit connector, if properly fitted, is still a weak point plastic to plastic and or plastic to copper?
Thanks in advance

Push-fits are only weak points in general if not done correctly. But they are also more vulnerable to failing if frozen (I'm basing that on the first of its type - Bartol 'Acorn').

I don't recall ever having had a push-fit connection fail, either on copper or plastic pipe, provided it was done correctly. By 'correctly', I mean that there were no 'burrs' on the end of the pipes that could damage the O rings, no stupidly-deep grooves or scratches on the pipe surface, support inserts of the correct type were always used on the plastic pipe, the pipes were inserted the correct - full - depth, and the fittings were undamaged (they can be reused, but you best know their provenance).

I have seen things go wrong - including for me - when one of the above was not observed, always 'accidentally'...

I trust you are not considering using plastic pipes and fittings in order to save on lagging? But, if I had a situation where the freezing of pipes was a known risk, or the consequences of it happening serious (eg pipes buried in the ground, or in a loft where water damage would be more serious), then I would choose plastic over copper every single day, but obviously also lag it. I repeat - it is significantly less likely to freeze in the first place, and less likely to fail should it freeze. Plastic is a much better insulator than copper*, and the wall thickness must be at least twice that of copper, perhaps x 3?

* hold a 6" piece of plastic pipe in one hand, and a matching piece of copper in the other. Stick both ends in a blow torch flame.

Hi
Many thanks for the detailed response, appreciated.
From memory one of the rentals, not had a look for a few years and will check, the bathroom and ensuite had a bit of plastic piping in the loft and exposed chrome pipe leading to both showers. I can't recall if the joints were properly covered or the bit of the patic about 2/3 meters in total length from mem. We did remove the water tank from loft.