Securing Bar Shower valves

[Crofter]

Just picked up this thread, noticed Nick 'Hallowed be His name' the pie eater saying not to use compression fittings on plastic pipe.

I've had my wc cistern plumbed in using this combination for a few months now, it's a temporary install at the moment but I had been planning on doing everything this way. I don't really trust push-fit for some reason, and the fittings are quite chunky. I'm also rather prone to changing my mind and like the idea of being able to reconfigure something easily.

It's not too late to swap to push-fit. Although it is decidedly too late to do anything about the long Hep2o runs that are now thoroughly boarded away.

Are compression fittings on plastic liable to fail at some point down the line?

[dpmiller]

used inserts?

[Crofter]

27 minutes ago, dpmiller said:

used inserts?

Absolutely.

It seems not everybody does. In our current house we've inherited some very poor plumbing done without inserts, with drips everywhere. Bunch of cowboys...

[TerryE]

The Hep2O installation manual explicitly states that you can use copper compression fittings on Hep2O pipe but that the inserts are essential.  I haven't got any now Hep2O into copper compression now, but I used a few after we put in the manifolds including during the 7 bar pressure test and didn't have any issues.

 

You can also put 15mm copper pipe into Hep2O fittings and that's how we did our tails using Hep2O elbows to do the change from Hep2O to copper.  "Feel the rumble" twists are essential even if you don't feel the rumble -- said the actress to the bishop -- to cut the lock ring into the pipe.  

[Nickfromwales]

Most MI's state it's use, but the success is solely down to not over tightening the fitting. On copper the olive has to press firmly onto the pipe and only deforms slightly, but when you tighten an olive onto soft plastic it is free to continue to bite into the plastic, deform the olive excessively, and also allow the compression nut to travel to its last thread therefore losing any opposing force from the olive. If the pipe ever gets pulled / moved then the olive is free to further 'chew' into the plastic which has memory, so the seal between the olive and the pipe o/s diameter gets compromised. 

Ive done this many a time on site for a temporary feed for plasterers etc, but I'd never bury a joint like this in my, or a customers home, it just isn't necessary. Hepworth fittings are bombproof so why stray away from an excellent solution to save one more fitting. ?

 

Compression fitting > section of copper pipe > Hepworth fitting > Hepworth pipe > Sleep peacefully. ?

[Crofter]

Wot he said!!

Turns out I got pretty lucky with my Hep->comp connections. I initially had a wc cistern set up like this for use as a temporary site toilet. When I put the shower valve in, I 'borrowed' this connection, stuck a compression tee on it, and fed this to the two sides of the shower valve as a pressure test.

The valve and its Hep2O fittings were fine, but the temporary tee was absolutely peeing everywhere. Slapped some self amalg on it just to allow me to do my test but it's been enough to convince me not to rely on compression fittings on Hep2O for any permanent connections.