Compression Fitting Queries

[Cod Roe]

Two quick question on compression fittings.

Firstly, I want to run a hot and cold water "main" across a room and put in appropriate tees to feed the various items that will eventually be fitted, the new toilet for example, however before I put the final supply pipes in for these I would like to finish off other jobs in the room, so would like to temporarily blank off their connection. Can I use these (it is 15mm pipe work):

are thread sealing, but compression tees are usually olive sealing, does this matter or will they leak (obviously I will PTFE the threads)?

Secondly, how do these work:

can't understand what clamps the smaller pipe, as they aren't supplied with any olives.

Thank you in advance for any help.

[Tony Bryer]

I would use one of these

you need to reconnect, just remove the blanking end and replace with a compression coupler.

I can't quite make it out from the image, but usually these fittings are in two parts with the outside profile the same as a 22mm compression ring split into two haves enclosing a 15mm compression ring which seals the smaller pipe. As you tighten the 22mm capnut it makes a seals between the

22mm fitting and the inner part of the fitting reducer, and the force also forms a seal between this and the 15mm compression ring and tube.

[sm_jamieson]

What I do is put in the service valve (you should use one per fitting). I shut off the valve, and also use a screw-on end cap with a washer (fibre or rubber) to seal the end as a double precaution. Compression end not really designed to be used with a washer, but as a temporary measure it's OK. If course this is no good if you need to seal off below floor level ! Simon.

[RobertL]

but be careful: the length of copper pipe projecting beyond the olive is not standardised. This means that if you fit one compression fitting (like the blank) and later replace it you can find that the new fitting does not have room for all the projecting pipe. THis measn that the olive is too far down the pipe.

Solution: don't push the pipe right in to the fitting. Instead, set it only a little beyond the olive. Or get a gadget for pulling off olives...

Robert

[Ed Sirett]

The more recent versions are one piece, the middle of the reducer is thin and acts much like a normal olive.

[Lobster]

Why don't you just use pushfit stop-ends - these just go straight over the cut end of a copper pipe. Then you can fit your permanant fittings later, when you know exactly where they need to go. I swear by these things - I use them all the time when in the middle of plumbing jobs:

(annoying to see Screwfix only sell 'em in 10s now - I reuse mine and that would last me years!)

David

[DavidM]

Are plastic push stop ends ok to use on copper pipe where they will then be hidden, semi permanently, (eg under floorboards or behind a bath panel)? I'm removing a basin in a bedroom and the pipes come through the wall from under a bath so access is a bit difficult for soldering or spanner. Is a conventional pipe cutter (not hacksaw!) ok to use, or should I smooth of the cut end of the pipe as well? I've also seen some brass push fit stop ends in Wickes - any good? David

[Lobster]

Well, pushfit fittings per se are designed for use everywhere, including hidden areas, and stop ends are no different in that sense. So I'd say that's a yes.

I always use a pipe cutter with them on copper tube - it provides a smooth, inwardly curving cut end so won't damage the 0-ring in the fitting.

David

[EricP]

I think his idea was to just have the compression T junctions capped directly with the little caps and not actually stick any pipe in them yet.

I love those little push fit things as you seem to do. They are in use all over my house.

Sadly they are also misused. My new next door neighbour asked me to look at a mysterious 22mm pipe that came out of the ground floor into a closet in the hall last week. It was capped with a quarter turn water valve and then one of the plastic push fit caps. It was a gas pipe that fed the old boiler that used to be there. Neither fitting is gas rated. Now he has to pay for it to be capped properly.

[Cod Roe]

Yes, that was my intention, but reading through what has been said this doesn't sound like it will be a leak free option?

[EricP]

The compression fitting isn't designed for capping like this but lots of water fittings of this type can be easily made suitable.

All you need is to make sure that the end of the pipe has a flat edge to it that will make a decent seal with a fibre or plastic washer. As made, the fitting may come with a sharp end to it where the thread has been cut on it. This sharp edge will not make a good seat on the washer and may actually cut it when screwing up.

All you need to do is rub the sharp end across a file of even sandpaper to make a flat end and it will then work with a washer type of cap or with the olive as designed.

If it is a brass type of fitting, two good strokes of a new file may be sufficient to make a good washer friendly surface.

[A.Lee]

The most obvious thing for me would be to put in the 'T', then a 2" length of pipe, then an iso valve:

You only need to connect one end, leave the other ready for connection. Pack of 10 for £7.19, then you wont have to turn off the water when you come to connect up the new appliances. Alan.