I am fitting a thermostatic shower valve into a stud wall.
The feed pipes will be surface mounted on the other side of this wall (as they will be hidden at the back of a cupboard).
I got a couple of male 90=B0 22-15mm compression couplings to fit onto the end of the pipes and up into the valve hot and cold inlets. This way the pipes can go straight through the wall at a right angle.
When fitting the 90=B0 couplings to the valve, how do I make them both point in the correct direction (i.e. at right angles to the wall, so they meet up with the feed pipes) when they are fully tightened?
When dry fitting to near maximum tightness, they end up pointing in completely different directions, neither of which is 90=B0 to the valve body!
Do I cut then ends so that they point where they should when they "ground out"? If so, how do I calculate this?
You're not reading the OP's question right. What he is saying is that when the 90 degree bends are hand tight they do not point in the desired direction i.e. backwards. I had a similar problem to this when I installed a shower pump and needed the bends to point at a certain angle. I tried PTFE (no good), waxed string (no good) and finally a suitable sized fibre washer(s), worked perfectly and has done for over 5 years to date (touches wood!).
I think people are having trouble working out what you're trying to do. The only explanation that makes any sense to me is if you're somehow trying to attach the compression elbows directly to the shower valve compression fittings*. Lord knows how you'd achieve this. What you're supposed to do is attach the shower to 15mm pipe using the compression fittings normally supplied.
So if you use short sections of 15mm pipe between your elbows and the shower valve Bob will be your uncle.
Don't tell me it doesn't have compression fittings! All showers do, don't they?
Hmmm, do you actually mean you have compression fittings (i.e. ones that use an olive and a back nut to tighten)?
I susspect that one end of your fitting may have a BSP parallel thread connector and not a compression connection. If this is the case they will simply screw into a socket and not have any nut to tighten as such.
No there is not usually any need to go cutting threads (unless they are too long for some other reason). What you need is PTFE tape and lots of it. Threaded connections don't have any way of making a water tight seal by themselves (unlike compression fittings). So you wind many turns of PTFE tape round the threaded bit and then screw it in (it will be much stiffer to do up). This will make a water tight connection by itself, so all you need do is stop turning when the connection is mostly screwed home, pointing in the right direction, and *not* bottomed out in the fitting.
No. Mostly they have threaded fittings, which need to be attached to compression fittings to go to copper pipes.
If this is what the OP is on about, i.e. how to get them tight when pointing in the right direction, the answer is 'lots of PTFE tape and stop before they are tight'
Apply plenty of Fernox LS-X thread sealer to the threads. You can then tighten the fitting until it is at the angle you require, and the Fernox will set and seal the fitting.
The only slight caveat is that the joint won't be solid, so you should ensure that pipework either side of the fitting is well fixed.
The feed pipes will be surface mounted on the other side of this wall (as they will be hidden at the back of a cupboard).
I got a couple of male 90° 22-15mm compression couplings to fit onto the end of the pipes and up into the valve hot and cold inlets. This way the pipes can go straight through the wall at a right angle.
When fitting the 90° couplings to the valve, how do I make them both point in the correct direction (i.e. at right angles to the wall, so they meet up with the feed pipes) when they are fully tightened?
When dry fitting to near maximum tightness, they end up pointing in completely different directions, neither of which is 90° to the valve body!
Do I cut then ends so that they point where they should when they "ground out"? If so, how do I calculate this?
All the ones I've seen have threaded fittings that enable you to connect to
15mm copper pipe using the supplied nuts and olives. If they aren't compression fittings then the Pope is not a Catholic. Perhaps if you're talking about something else you could illustrate by pointing to appropriate examples at Screwfix or BES?
Sorry for responding so late on this. Thanks for all the good replies by the way, it seems I was not alone in this!!!
Having spoken to the kind chap at my local plumbers' merchants, I was advised thus...
If using 90=B0 Male 'Irons' (they are not compression fittings but male threads that fit into the female threads of the shower valve. They no longer seem to be supplied with any valves as manufacturers have realised they can't account for the angle required by the feed pipes for 'ALL' installations and it's cheaper to just not include them!) using plenty of PTFE tape (or alternatives) is the answer.
Wrapping lots of it on, and perhaps creating a 'taper', near the knuckle, by twisting the reel, as you wind it around, means the seal will be watertight, even when the fitting is not tightened to its extreme. Thus, the elbow can be rotated to suit the position of the feed pipes.
Even so, this does take a bit of practice to get the right balance between adjustability and watertightness, and it means you have to be able to do a 'wet test' before sealing the valve up into the wall with WBP ply, plasterboard, tiles etc which is not always convenient.
A better suggestion for this situation (and the one I used) is to always use 'straight irons' (like compression straights but with no olive or backnut on the shower-valve-side of the fitting). This can be fully tightened, with PTFE, into the shower valve, without any doubts about leaking. To get the 90=B0, 45=B0 or other degree angle pointing in the direction of the feed pipes, simply use a 'Street' or 'Stem' copper fitting (of the desired angle elbow) in either 15, 22 or 28mm. These are fittings which have different diameters on either side i.e. one side 'holds'
22mm tube while the other 'is' 22mm. In my case, I used 22mm, 90=B0 street elbows... the 22mm side slotted into the straight-male-iron, rotated to desired position and then compression fitting tightened, locking it in place... then other side recieved small length of 22mm tube soldered and linking valve to feed pipe locations. It's a bit hard to explain without diagrams, but by using "Street" fittings, any situation can be dealt with, without the doubt of leaking PTFE joints.
Hope this is useful to someone and thanks again for the replies.
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