Plumbing pipes - copper v plastic, different sized pipes

[Porthole]

Hello

 

Please can someone tell me if it matters if different types and sizes of pipes are used to plumb the house? We have all manner of stuff being used - didn't know if it affected pressure or anything. Is plastic just as good as copper these days? I've never come across it - we've always had copper pipes installed by the plumbers in the past. 

In one bathroom, they have used copper to connect to the shower valve, in the other it is plastic. I asked why and they just said it was what was available. 

 

Be grateful for your thoughts.

 

Thanks again

 

 

[Conor]

Looks exactly same as us. Plastic push fit is generally used on long runs from source to outlet. We used copper for the last few bends and connections to outlets as you need straight pipes to it to be a neat job. 22mm coiled plastic pipe is hard to use in tight spaces as you can never pull it straight. Also most taps etc use compression fittings, so copper is best. Same at the other end at the manifolds / tanks / pumps etc. Our build has everything from 10mm plastic push fit, to 1" hand soldered copper via everything in between.

[Ajn]

Having had a couple of failures of the O ring with push fit to copper after five to seven years.  I would only use compression joints on the plastic to copper. On inspection some form of crystallization had taken place over a long period within the joints and caused failure of the O ring. The two joints were different. One was an inline connector (copper copper) and the other was a copper to flexible.

The flexible (7 years) had a very positive drip and the inline connector (five ish years) was damp at both ends. These were the only two we had in the house at the time. Our current build has lots of plactic plastic push fit but no plastic copper push fit .

 

Just my personal experiance.

Edited February 8, 2022 by Ajn

[PeterW]

20 minutes ago, Ajn said:

Having had a couple of failures of the O ring with push fit to copper after five to seven years. 

Which brand of fitting failed ..?

[Ajn]

2 minutes ago, PeterW said:

Which brand of fitting failed ..?

it was atleast five years ago so a few sleeps since then. Likely to have been local building supplier so no idea. The inline one looked like the speedfit ones.

[PeterW]

JG should be marked, the standard grey nondescript ones I never trust ..! 

[jayc89]

I plan to do exactly the same with our extension. Our plumber used copper everywhere for the original house renovation and we get so much knocking/banging as the heating comes on/off it's unreal. I should get him back but I really don't fancy pulling the new carpets etc up to get it fixed. We'll have to live with it for now.

 

The majority of the runs being plaster and just the bits on show being copper should reduce the vast majority of this problem.

[Porthole]

4 hours ago, Conor said:

Looks exactly same as us. Plastic push fit is generally used on long runs from source to outlet. We used copper for the last few bends and connections to outlets as you need straight pipes to it to be a neat job. 22mm coiled plastic pipe is hard to use in tight spaces as you can never pull it straight. Also most taps etc use compression fittings, so copper is best. Same at the other end at the manifolds / tanks / pumps etc. Our build has everything from 10mm plastic push fit, to 1" hand soldered copper via everything in btween.

Thanks - good to have an explanation for why different pipes are used. Some plastic ones are thinner than the others though and just wondered if that matters from pressure etc point of view. If that is ok, should the only issue be the connections between the different pipes?

Thanks

[PeterW]

1 hour ago, Porthole said:

Some plastic ones are thinner than the others though and just wondered if that matters from pressure

diameter affects flow usually rather than pressure when pipes are long. 

[hb1982]

Good quality plastic if installed properly should last as long as copper. When installing plastic:

 

1. Use as few fittings as possible. use cold form bend fitting where possible.

2. Support and clip pipe as per instruction, usually every 800 to 1000mm

3. Only use pipe and fittings from the same manufacturer

4. Remind to install one size bigger in plastic installation. e.g. 15mm copper is (I.D. 13.6mm); Plastic 15mm (nominal) - I.D. is 11.3mm.

5. Press fit is better than push fit but not usually available in domestic contractors

6. PEX pipe is far better than grey PB pipe. 

 

 

[MJNewton]

7. Always use inserts!