Copper & Plastic plumbing - freely mixing and matching?

[Frank Stacey]

For various reasons I find that a plumbing job on which I have embarked involves using plastic (HEP) pipe for various awkward runs with copper at either end. Am I right to assume this can be done without restriction?

In some places I am using straight metal compression couplers between copper and plastic with an insert in the plastic pipe. In other places I have plastic elbows with plastic on one branch and copper or chrome plated copper on the other. Are there any gotchas I should know about?

Excuse the paranoia, but once completed most of this stuff is going to be under the floor of a small bathroom and very inaccessible. I dread having to rip out my carefully installed fittings as water seeps through the ceiling below!!

Frank [the tentative plumber]

[R Taylor]

you can mix copper and plastic tube, no probs. fwiw, I wouldnt waste time with potentialy problematic compression fittings, I'd use speedfit throughout.

fit and forget.

RT

[Andy Hall]

Check with the manufacturers, but generally push fit fittings for plastic are OK with copper, but not with chrome plated copper where they are apparently prone to slide off.

If you have to use chrome plated pipe, then it is better to transition via a compression fitting and short length of plain copper tube to the push fit fitting.

It's also important to follow the manufacturer's recommendation and use a proper pipe cutter for the plastic and not a hack saw.

[Set Square]

That'll work fine. Just make sure that all pipes - whether copper or plastic are pushed home fully into the fittings. (make a mark on the pipe with a felt-tip pen the right distance from the end, and make sure that this is only just visible).

My only reservation would be chrome plated pipe - having never used any! It may be ok, but I would be slightly worried in case the chrome is too hard for the star-lock washers to dig into and grip properly. I would be tempted to use compression joints here.

[IMM]

Of all the plastic systems Speedfit is the least desirable. Hep is superior.

[IMM]

You cab use as hacksaw as long as the cut is square and the burrs are trimmed off with a Stanley knife. No sense in spending £15 to do a few plastic joints.

[Andy Hall]

You mean as described in

probably every other manufacturer.

??

None of these leading manufacturers recommend the use of a hacksaw to cut their products, but presumably you know better than all of them.

The whole purpose of using a cutter is to cut the pipe cleanly and squarely.

The application is to go under a bathroom floor where there will later be limited access. In that context, spending £15 on a proper pipe cutter as recommended by the manufacturers is a sensible investment in doing the job properly rather than bodging it as you are suggesting.

[fred]

In article , Andy Hall writes

I agree, with all of Andy's comments, but would add that my own rule is never to use a fitting that is mechanically weaker than either/any of the pipes to be joined, so if I am making plastic/plastic I use plastic, copper/plastic I prefer to use compression and copper/copper I would never use plastic. All to do with the risk of stressing/damaging the fitting when pipes inevitably get moved about during fitting and in the months/years down the line.

[Dave Plowman (News)]

Yes - others with some skills may be able to. But *you* apparently can't.

And what's a few leaks under floorboards as opposed to saving 15 quid. Nothing at all to a dedicated bodger...

[Dave Plowman (News)]

I find it amazing the way IMM constantly recommends wasting vast amounts of money with his many harebrained schemes that aren't in the least practical for most, but penny pinches on tools at every opportunity. Which just confirms my belief that he has little or no hands on experience of the actual installation of any form of heating system - or indeed anything else.

[Frank Stacey]

I have a cutter for copper pipe, one which is rotated round the pipe as a circular blade is pushed gradually into it. Is that acceptable - it certainly didn't cost as much as £15?

Frank

[IMM]

If it works and gives a clean cut, yes. If you are doing a whole system then a pipe cutter is worth getting as it is quick, but not for a few joints. All you need is a good square cut with the sharp burred edges removed with a fine file/Stanley knife. The pipe insert will but up against the pipe which is tapered to allow the O ring to slide on.

When pushing the fitting on check to see if the O ring has been dislodged. Speedfit are prone to do this more than others, but all makes can be dislodged.

[IMM]

How would you know? You know nothing of heating and water systems.

Penny pinching. I am say don't buy it, not buy a cheap one. When buying one buy a very good quality pipe cutter.

Here is this Plowman giving advise on CH..read on...

This what he wears, yes he does...he said... "Well, I got a rather flash pair of DeWalt boots from TLC, so there.;-)"

Sad isn't it. Big yellow boots. Yes. big yellow boots.

He also attempts to give advise and criticise views on heating, yet he said about his gas boier.......

"Mine managed over 10 years without being touched before it needed a clean. 'Sooting up' once it starts, happens very quickly."

He didn't have his gas boiler serviced for over 10 years, and knows all the answers in this field - he thinks. Only on the Internet you see this. These people are dangerous man, very dangerous.

[IMM]

Do you mean this poor man has to spend £15 for nothing? My oh my!

Please look ..

'm sure you have never used one.

[IMM]

Here is what Hepworth said on this ng. This man is using Hep20...

"The inventive can find many ways of achieving a perfectly acceptable clean, square cut using a variety of tools. The Hepworth Plumbing Products Team"

A "perfectly acceptable clean, square cut" can be obtained by using a hacksawa dn removing the burr and swarf with fines files/Straley knife.

< snip tripe by makers wanting sell over-priced tools >

[IMM]

Can you elaborate please. What you say doesn't makes sense as all joints: plastic, copper, brass, etc, will move in use due to expansion. In joints were there is excessive movement it is a concern that the O ring , although keeping a seal will prematurely wear. Osma Gold has O rings with two contact points. The O ring shape is a "W". This may prolong wear.

You can use a plastic joints on two copper pipes. I have seen these done successfully on cold water. You can use copper or brass pushfit fittings on two pieces of plastic pipe. Both are better than plastic/plastic as the metal parts, pipe or fitting, is less prone to expanding and warping with stress or heat.

Many plastic systems develop intermittent leaks, when the pipes and fitting expand when they heat up.

[Andy Hall]

Not really, Frank.

I did try this once as an experiment, just to see what would happen, but it tended to crush and mangle the end of the pipe, especially if the cut is near the end as it would be for trimming.

It's best to use a proper plastic pipe cutter. I've seen these in B&Q etc. or plumber's merchants have them. An example is

catalogue number 13489.

Another thing to look at when buying pipe is that some brands have marks at measured intervals that correspond to the push depth of the fitting. Speedfit have these and possibly others. The idea is that you cut on a line and then push in the pipe to the next line to ensure proper insertion depth.

[Andy Hall]

I imagine that this would assume a degree of competence.

In their instruction leaflets, and web sites, all the manufacturers do not recommend the use of a hacksaw but do recommend a proper pipe cutter. At a cost of about £12, it is a nonsense not to buy one. It's the cost of about 4 fittings.

Why on earth would anybody want to screw around with hacksaws, making a mess, having to play around with files and knives to ensure the cut is square and clean, when the whole thing can be done in a fraction of a second with the proper and inexpensive tool.?

[Mark S.]

I think when I bought both my wheel and plastic pipe cutters the wheel one said to either use only on plastic or on copper not use it on both?

I'd splash the cash on a proper ratchet plastic cutter (Screwfix one has done me ok).

Mark S.

[Set Square]

Nah! That'll snaggle it!

A pair of garden secateurs (sp?) is is fine though. Any slight squeezing of the pipe is immediately rectified when the insert is pushed in.