Installing shower S unions

[TrevorIOW]

Hi all,
Ok, I’m electrically qualified so please excuse me if I use incorrect plumbing terms or expressions.
Today’s stupid question relates to the installation of a thermostatic shower by Grohe.
The unit in question is an exposed bar that screws onto two s shaped eccentric tails or stubs that screw into the wall plate. The instructions always say to wrap ptfe tape onto the threads and screw into the wall plate.
Now, in order to achieve 150mm centres and level, it means that the fittings never tighten down onto a seat. That is, the fittings might only be 90% into the wall elbow.
That might work short term but I imagine the fittings are not exactly tight and in time, they’re going to move and leak.
To make things more difficult, the Grohe S unions seem to have serrated threads that demolish the ptfe tape.
So, how do you install S unions firmly and leak proof?
Thanks in advance
Trevor

 

[Exedon]

Use loctite 55 cord or loctite 577 liquid
55 is my go to can even slightly back the thread without problems.
Better still chuck those stupid connections away and bring copper through wall then use something like bristan WMNT 10C connectors.

 

[TrevorIOW]

Thanks for the quick reply.
I’ve looked at the Bristan and I like the idea of continuous pipe within the studwork. I just can’t trust the S unions. This job is in a timber frame house so I’d always worry about leaks within the wall.
Thanks again for the helpful advice.
Off to the plumbers merchant for the Bristan.
Cheers
Trevor

 

[Laurieo]

Or get a bar shower wall plate ,which will keep your pipe centers .

 

[TrevorIOW]

Hi Laurio,
Fair comment. I see that the my local merchants stock the Bristan 10C and the 11C. That is, individual outlets and the double plate.
My particular project has a stud wall sheathed in ply. This will then be finished with Mermaid shower panels. So, if I get this wrong, I’ll have to demolish the wall to get to the plate. At least the 10C individual outlets, the entire thing is outside of the finished wall.
The plywood and Mermaid panels provide a perfect surface to mount the Individual outlets level at 150mm centres.
I guess I worry too much. However, a working life ensuring systems fail safe makes me invent possible scenarios that may never happen.
Thanks again for the helpful advice. It’s very much appreciated.

 

[kidgreen61]

Please save yourself a world of pain and throw those "S" things in the scrap. If ever they leak, you'll be forced to take tiles off to repair, as said above, use either a plate, or just carefully space your tails at 150mm, and make sure they're level, you just put adaptors on after tiling then, and in the event of a leak, everything is accessible to repair.

 

[TrevorIOW]

Thanks for the advice.
Yep, the S unions are in the bin. I tried them several times and found that they’re too prone to moving and leaking. I’m not impressed that Grohe supply them. Their instructions suggest burying them in silicone so I was suspicious from the start.
The wall is not tiled but panelled. So, the option to remove a couple of tiles wouldn’t work. The wall would need to come off.
As you say, adaptors onto the finished wall is by far the best option.
Many thanks for your reply.