I need to provide a 15mm x 1/2" BSP fitting to allow a new shower to connect.
Fine - got the fitting - no issues.
However, teh shower fitting is a 90' elbow, and needs to be screwed in and once in and tight it needs to be vertical.
The other end of the 15mm x 1/2" BSP fitting is compression fitting to
15mm pipe which will be hidden behind (new) wall.
Now - the stupid question time....
When fitting together, obviously using PTFE tape around the thread, does the 90' shower elbow need to be screwed in until *TIGHT* - or can it be screwed in as far as possible whilst retaiing the upright final position.
(e.g. do I need to work out which orientation to connect to the compression 15mm pipe before I fit? Or - does the PTFE and the join make it watertight?
Also - the answer should answer the next question as to if a washer is needed - but guess if it needs to be *TIGHT* then yes; and *tight as poss whilst keeping orientation you want* is no.
I'm assuming this is the same as the Triton I did a couple of weeks back.
No need for PTFE tape. The threads on a compression fiting aren't there to make a seal.
If I understand this right, you need to keep it definitely vertical. Grip the body of the fitting with Stillsons, then tighten the nut on the pipe-side up until it is a tight seal, holding the body vertical at all times.
Then place the shower on the wall and push the plastic spigot of the shower into the fitting (with nuts and olive). You need a few inches of unsupported pipe, so as to allow enough flex. If you do something impractical to get it all together and rigid without this, you'll never be able to work on the shower in the future.
Then tighten up the shower-side nut. Hold the fitting with Stillsons again, and do not allow it to twist. That plastic spigot fitting is very expensive to replace!
For sealing the threaded part of the fitting I'd use a sealer like 'Fernox LS-X', putting a reasonable amount on the male thread. This is so any excess is left on the outside of the fitting when it's done up.
A little sealant on the female thread should be OK, but not so much there is any excess inside the fitting. If it's a straight fitting it may be possible to see through and check its OK.
Then before the sealer sets do up the compression fitting, and get the orientation of the shower as you want it. The threaded part doesn't have to be tight to seal, but there needs to be some other physical means of support to stop the fitting twisting as the sealer remains soft when set.
Try and get some copper olives for the compression fitting instead of brass olives, as copper is softer and there is a better chance of seal with a brass-copper-copper combination than brass-brass-copper.
Also don't push the pipe all the way into the fitting but back it off
1/16", so that when the fitting is done up the pipe won't 'bottom out' inside the fitting as it's done up.
You might like to try a dry run with a short stub of copper pipe on the compression fitting, this will let you see inside the pipe to tell how much tightening is needed before the olive deforms the pipe. Ideally the fitting should be done up until the point that this just starts to happen. Don't reuse the olive though.
The sealant is supposed to take 1 or 2 hrs to set but I'd leave it overnight if possible to set, it won't hold pressure straight away (how do I know? =) )
If the compression fittings leak when the water is turned on they can be done up one flat (1/6th) at a time. If they keep leaking regardless I'd redo the compression fitting using some LS-X on that around the olive and threads, this shouldn't be necessary though.
I'm no plumber, but have had good success doing the above in installing a bar mixer type shower. If anything is unclear or there's anything else I can help with, please post.
Bear in mind that Stilsons are designed to "bite" into the metal you are trying to hold. A nice chromed finish with deep bite marks from Stilson jaws is unlikely to cut much mustard with SWMBO.
Plastic is even less resistant to damage than Chromed Brass :-(
You don't need a chromed finish, nor are Stillson bitemarks a problem. The elbow joint is hidden inside the plastic case of the shower unit.
For a Triton the final entry is from the bottom, but you can run a pipe in from above, below or either side. The bed (top only) and the final compression joint get hidden,
As I recall none of your points in this post were made clear to the OP. aqlso remember the answers are read by many more people than the OP, some of whom have been known to take "advice" as gospel. I've come across far too many fittings and finishes butchered by stilsons to simply assume everything in the garden is rosy. Don't get my message wrong - Stilsons are excellent tools when used for their intended purpose which is to grip and turn steel pipe. Decor finishes and "nuts" should be treated with respect and more appropriate tools such as correctly fitting spanners/adjustables or grips with protected jaws.
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