Electric shower plumbing problem...

[Donquixote]

Hi,

I'm a novice DIYer (I can hear the groans already!). I've just bought my first house and I am having to do a lot of the required work myself due to a tight budget. I'm currently replacing my electric shower with a, basically, like-for-like model (Gainsborough Stanza 8.5kW): I've removed the old unit, fitted a chrome elbow compression fitting to the water pipe that comes in through the wall (replacing the old brass one that was badly corroded), and mounted the new unit on the wall...
...my problem is, the inlet pipe on the shower unit is plastic, yet the installation guide says it must be connected to the water supply via a 15mm compression elbow, using a copper olive (which is supplied). But the compression elbow does not fit tightly to the plastic pipe and can quite easily be slid back and forth, so when I turn the water on the pressure causes the elbow to slide straight off the pipe and soak my bathroom!
I have read the installation guide aver and over but this is the only direction it gives. I'm sure the solution is simple but it is driving me crazy. Please help!

Thanks,
Don

[alavahalf]

If you are using plastic pipe with a compression fitting are you aware that you need to slip a pipe support /insert into the plastic pipe before using the compression fitting...otherwise the plastic pipe may collapse.

http://s7g3.scene7.co...age/ae235/57178_P?$p$

[Donquixote]

Really? Thanks for that, I didn't realise. After asking around it appears that I'm just not tightening the nut enough to compress the olive properly, but before I tighten it up again I'll pop in an insert.

Thanks again, I really appreciate it.

Don

[buildersmate]

Both Speedfit and Hep2O state to use sleeve supports when using their pipe - irrespective of whether it is linking to their proprietary plastic fittings or whether it is used into a brass compression fitting. It may be possible to get away with it on 15mm plastic pipes, but not recommended.
http://www.johnguest.com/linkpages/FAQs.htm
http://www.hep2o.co.uk/v2Opipecutting1.htm

[alavahalf]

Last year I re-plumbed our whole house (over 3 floors) using Hep20 push fit.
I used about 60 connectors ... the one and only connector that leaked ... was the one where I had missed out inserting the support sleeve... ;-)

http://www.hep2o.co.uk/v2Ojointing1.htm

[The Builder]

Forgive me shoving my nose in, but I think we're in danger of confusing the Don here.
BM and Alava are absolutely right about Hep2O. I use it all the time. In this case though, as Doc says, shower spigots are usually rigid plastic. No insert is used in this case. A 15mm compression fitting brass) is all that's need in every case that I've seen.

[The Builder]

Oops ............... Doc got there first ................... Good Morning Doc :o)

[WILLWONKER]

Plus the fact in most cases there is a fillter pressed into the spigot, as been said you don't need one just be carfull not to over tighten or you may crack the spigot

[Donquixote]

Thanks for all your answers, guys...and sorry for the late response!
I fitted the pipe to the shower's plastic inlet without using any kind of liner, just the standard copper olive in the compression elbow, and it's been absolutely fine.
No leaks - job done.

Again, thanks for all your help and advice, it's greatly appreciated.