Plastic vs copper pipework

[DHutch]

The main part of my CH system is copper because it was what was used 20 years ago, the additional pipework that I have been adding over the last week or so is plastic Price/convenience/minimum joints in a run.

 

Our boats domestic plumbing was plumbed in original Hep20 25 years ago, launched spring 1991!

 

As said its faster, requires no real tools and not a lot of fixing down, integrates perfectly with copper and appears to be able to last. It also provides an amount of insulation, so hot pipe stay warm longer, and a very small amount more protection is given for short frosts.

 

That said, when you get a lot of joints, the need for tight bends, or for runs that are on show such as radiator tails, most then switch back.

 

Or engine has the water pipes go back to copper, due to the amount things above 100deg in the steam plant, and I have seen rat/mouse damage in a farmhouse plumbed in plastic. Neither are likely to effect most boats.

 

The radiator pipe work is again on show, and hence in copper for aesthetics, im not sure the larger 28mm size was in plastic at the time either.

 

 

 

Daniel

[DHutch]

Bugger I have used plastic inserts on some compression joints they havent leaked yet..................................

My house had compression onto no inserts in places, not that I recommend it. I understand the metal inserts should be used with compression fittings.

 

JG also have insets with o-rings on them, which provides a secondary seal using the inside of the pipe, marketed as being more robust, I think its mainly a work around for rough fitting damaging the outer wall of pipes.

 

I'm not certain (and if I'm wrong I am sure someone will be along to correct) I believe the modern plastic pipe is three layers of different plastics....one of which at least is XLPE (cross linked polyetheline) which is extremely tough and stable

 

Certainly most now appear to be multi-layer which I expect might not always have been the case, some are not also a lot more flexible than the older systems. Some also do semi-rigid pipe I think too.

 

 

 

Daniel

[bag 'o' bones]

As a plumber of a certain age, might I say I detest platic pipe with a passion.

It is for DIYers and people who cant solder properly.

What did I use on my boat? Plastic pipe and pushfit fitings it is a no-brainer, just use loads of clips and hide as much as you can.

Bit of a sweeping statement!

 

Try telling that to a brewery dispense technician!

[Chewbacka]

My house had compression onto no inserts in places, not that I recommend it. I understand the metal inserts should be used with compression fittings.

 

JG also have insets with o-rings on them, which provides a secondary seal using the inside of the pipe, marketed as being more robust, I think its mainly a work around for rough fitting damaging the outer wall of pipes.

 

 

Certainly most now appear to be multi-layer which I expect might not always have been the case, some are not also a lot more flexible than the older systems. Some also do semi-rigid pipe I think too.

 

 

 

Daniel

If I remember correctly the thin barrier layer was introduced to reduce Oxygen permeability for recirculating heating pipes to reduce corrosion of radiators etc.

[Dave Payne]

On this subject, i have plastic pipes, one side of the boat i want to replace the whole run from stern door to bathroom with something a bit better, not keen on copper but was thinking stainless supported by brackets off the floor.

 

Is this feasible?

[the barnacle]

I have just been plubbing out outbuilding, Copper with slim copper pushfit are a much neater job -

 

plastic pushfit are bulky, - i think both have advantages depending on area of use. but plastic pipe comes in when you want to weave a long length through bendy areas without having joints.

[DHutch]

Yeah, the copper push fits don't look half so bad do they.

If I remember correctly the thin barrier layer was introduced to reduce Oxygen permeability for recirculating heating pipes to reduce corrosion of radiators etc.

I'm not sure if I am honest. Certainly while it was Grey all the way through, now most of its white with blue in the middle. More than that I cannot say!

 

 

Daniel

[Graham.m]

I've looked around a number of used narrowboats recently with a view to buying one in due course should our forthcoming week's holiday prove successful.

 

I've noticed that most of them have their water and central heating pipework in plastic (PolyPipe, Speedfit or similar) rather than the traditional copper, and wondered if this was for a particular reason.

 

I thought perhaps it was because there was less chance of vibration fracturing plastic pipes, but having had what I hope is a thorough search on here, I've not found an answer. Can anyone help please?

 

Apologies if it's been covered before, but thanks for any replies folks.

 

Suspect it is related to cost price of copper went very high. Plastic does have some advantages of its own, less likely to burst in a freeze, easier to work, less prone to vibration damage oh and cheaper.

[MtB]

 

Suspect it is related to cost price of copper went very high. Plastic does have some advantages of its own, less likely to burst in a freeze, easier to work, less prone to vibration damage oh and cheaper.

 

 

Please don't start on the plumbing threads as well now!!

[nicknorman]

Please don't start on the plumbing threads as well now!!

We're doomed, I tell you!

 

Mind you, gas is yet to come, be grateful for small mercies!

Edited December 15, 2015 by nicknorman

[MtB]

We're doomed, I tell you!

 

Mind you, gas is yet to come, be grateful for small mercies!

 

 

When we get around to gas I'm sure I'll find out loads of new stuff I didn't know...

[system 4-50]

 

 

When we get around to gas I'm sure I'll find out loads of new stuff I didn't know...

Tee Hee!

[Keeping Up]

On our previous boat the central-heating circuit was plumbed in copper. The radiator at the far end of the boat used to move by about an inch as the system warmed up (and leaked terribly at first because the previous owner hadn't allowed enough room for the expansion). Plastic doesn't have that problem,.

[Graham.m]

 

 

When we get around to gas I'm sure I'll find out loads of new stuff I didn't know...

That I doubt you don't try and push it down peoples throats.

[jonathanA]

I have just been plubbing out outbuilding, Copper with slim copper pushfit are a much neater job -

 

plastic pushfit are bulky, - i think both have advantages depending on area of use. but plastic pipe comes in when you want to weave a long length through bendy areas without having joints.

 

Yep just been snagging a new build toilet/shower facility and was quite surprised to see copper push fit in use in commercial install. The architects were quite happy with it and I had to look twice to convince myself they weren't soldered.... Presumably the time saving makes up for the extra cost

[Guest]

Yep just been snagging a new build toilet/shower facility and was quite surprised to see copper push fit in use in commercial install. The architects were quite happy with it and I had to look twice to convince myself they weren't soldered.... Presumably the time saving makes up for the extra cost

Funny thing about soldered joints in that I was always brought up to believe they were the "proper job." However the soldered copper joints in the school where I used to work were failing at an alarming rate due to some kind of reaction at the joints causing "pinholing" of the copper pipework. Compression fittings and suchlike went up in my opinion (based on very limited knowledge of plumbing!)

[Joe the plumber]

That might have been the type of flux used, or possibly it hadn't been cleaned off afterwards. Or a dodgy batch of copper pipe or fittings.

 

I've never had that happen (so far....)

[John V]

I seem to remember my old man saying something, about how they used to make their own flux. (He was a journeyman coppersmith) spirit of salts ?

Maybe it was a badly made batch ?

[Joe the plumber]

It could be. I use self-cleaning flux and it will turn a copper pipe green overnight if you leave it on.

[Joe the plumber]

I found we had a wet floor on the boat yesterday. It turned out to be one of the wonderful nine year old Speedfit plastic elbows that had decided, untouched, to give up the ghost on the cold water feed to the wash basin. I was able to stop it dripping by turning the pipe in the fitting (yet another Joe the Plumber 'bodge' - I can imagine the keyboards being fired up even now...) and will attend to it properly shortly. It's not done much for my opinion of the stuff though.

 

I finished and pressure tested my new (copper piped) central heating system today and was pleased to find no leaks (soapy water on every joint, and 30psi happily maintained for about half an hour). Our car's footpump (and my legs) got a bit hot though!

 

If I can fathom out the electrics (the instructions are, er, concise), we may have some heating soon....

[system 4-50]

On 15/12/2015 at 20:18, Keeping Up said:

On our previous boat the central-heating circuit was plumbed in copper. The radiator at the far end of the boat used to move by about an inch as the system warmed up (and leaked terribly at first because the previous owner hadn't allowed enough room for the expansion). Plastic doesn't have that problem,.

Searching the forum I found this which is a disappointment.  I have just plumbed in my radiators in SpeedFit with a 13M run down the length of the boat.  When I heated them up, I expected a little expansion but I got a lot, with the pipes wiggling 6" away from the wall. I thought I might redo them in copper but this post says there is a problem with this too.  Are there any techniques for dealing with expansion that are not obvious? How do other people manage?

[Tony Brooks]

I just put extra pipe fixings in and then gave up and boxed the plastic pipework in.

[nicknorman]

You could build an expansion zig zag thing in - ie take the pipe through 90 degrees, down a bit, 90 degrees, along a bit, 90 degrees, up a bit, 90 degrees. Then when it expands it will just push the vertical bits out of the vertical. 

[system 4-50]

Expansion [mm/m °C]

steel. 0.0120

stainless steel. 0.0166

copper. 0.0168  

aluminium. 0.0232.

PE. 0.1800.

PVC. 0.2000. 

 

I've found the above data which I think means I have to accommodate ~13mm if I redo it in copper rather than ~156mm for plastics, which is much more manageable.  I'll also connect the furthest rad via rubber tubing which should help.

[Jen-in-Wellies]

5 minutes ago, system 4-50 said:

Expansion [mm/m °C]

steel. 0.0120

stainless steel. 0.0166

copper. 0.0168  

aluminium. 0.0232.

PE. 0.1800.

PVC. 0.2000. 

 

I've found the above data which I think means I have to accommodate ~13mm if I redo it in copper rather than ~156mm for plastics, which is much more manageable.  I'll also connect the furthest rad via rubber tubing which should help.

You think right. Better than an order of magnitude less thermal expansion with copper, compared with plastics.

Jen