Plastic pipework

[dennis]

I imagine so, its been in for 20 years.

You could get the brown PB stuff then but it wasn't really suitable for CH.

[Doctor Drivel]

He had better not. I will blind the man with science.

[Doctor Drivel]

Compression is last? Not if you buy quality joints it is isn't. I bet you use the cheapo Chinese/Italian crap. Buy Conex, even Screwfix sell them now.

Oh NO! Not again!! Compression is last? Not if you buy quality joints it is isn't. I bet you use the cheapo Chinese/Italian crap. Buy Conex, even Screwfix sell them now.

Again!!! Best use good quality compression joints on plastic pipes with the correct insert. The advantage of threading is still there and a far superior joint too. I know heating companies that have given up on pushfits and only use compression for jointing plastic pipe. They don't like comebacks, pushfits given that.

Also, plastic pipe has inserts which reduces the internal bore and can be a point of sludge build up.

The most problematic joints are pushfit, plastic or copper/brass - by a mile. When they fail it tends to be catastrophic with joints shooting off pipes. The resistance to pressure of some plastic pipe seriously reduces when hot. If near boiling they can easily split.

I know of instances where pushfits have failed after months after being pressure tested. Also of sites where the average failure is 1 per house. Ceiling falling in as open ends pour out is more common than what the makers like to admit.

I would use it only where it is easy to thread and preferably on cold water if possible. Good for garages, as they resist frost better than copper.

[Doctor Drivel]

Using manifolds is superior.

[Doctor Drivel]

If done properly installation time is no quicker. Plastic requires more clipping to reduce stress on joints.

[Ed Sirett]

ROTFL.

[Doctor Drivel]

If what you write is your experiences then you need more experience with plastic pipes. As your experiences do not match the industry as whole. Take note of people who know more.

[Ed Sirett]

It is possible that the 'industry as a whole' has a problem with plastic pipe. This is clearly not universal or a problem I have encountered. I have done several heating systems from scratch using significant amounts of plastic pipe. I have not had call backs on account of the pipe or push fittings.

It is just possible that a multi-unit house builder using lack lustre labour who neither check their work or have any inclination to read instructions have had systematic problems with push-fittings.

I do try to take account of people who know more. When I discover conflicting data then I have to weight the various opinions/evidences. That will in turn depend amongst many things on the credibility of the source...

[Doctor Drivel]

I know a number of men who install plastic pipes in new builds. Not one said they would have it in their own homes. They all say it is no quicker than soldered copper in first fix, as the house is an empty shell anyhow. Plastic is used so the Pikeys do not rip out the copper. On some sites they will get unskilled labour to fit the plastic pipes and a pro to do the difficult second fix usually in copper as it is on show (plastic pipe puts punters off), test and sign off.

On sizable sites all first fix is pressure tested. Occasionally one push-fit fitting will go after the new owner has moved in - even after 15 bar pressure testing. They have had a few ceilings collapse. The main complaint with installers is that the fittings are too hard too push on, even with grease (which need flushing out - so much for push and go and just a fill as one makers at one time was lauding). The most difficult Hep2O fittings were 12mm. After a few systems under performed, they had to up some 12mm to 15mm and 22m to 28mm, as the pipe inserts reduced the internal bore. The pipe inserts are a point for blockages after a number of years.

I also know a heating company, that does not do site work. After too many problems with push fit, they went over to using quality compression joints on plastic pipe, only using plastic pipe where needed like threading. They have not had one come back using compression joints. The only use Hep20 as the pipe inserts are metal - Speedfit are plastic. They avoid Speedfit pipe as it is too rigid and is not quicker than installing copper. On the H&C side they use non-barrier Hep2O as it is more flexible. I asked them how much would they use in a typical system they said most systems they install an element of plastic, but not much of it. They said threading long lengths and not clipping the centre part of the length is against the regs anyway, which is true.

[Andy Hall]

That only happens if the pie is used beyond its rating - i.e. trying to supply too large a radiator and having the flow rate too high as a result.

[Andy Hall]

Such as your newly refined technique for cutting plastic pipe with a hacksaw, contrary to manufacturer's instructions and producing a flood?

[Doctor Drivel]

Matt, please cut all your plastic pipe with a hacksaw and do not trim off. That is important to you. Do not trim off. Please do.