Suitable valves for 15mm cold water

In article , snipped-for-privacy@isbd.co.uk writes

Yes, no problem, just make sure you use the appropriate pipe insert. It's actually my preference to use compression fittings on speedfit where they might be subject to movement.

flow to the tap. On mains pressure you may not notice it however.

the photo indicates that this is a full flow valve that will not restrict flow. It is the safe option if you want max flow and easy isolation.

Yep, a full flow ball valve is just like having a full bore pipe when open and a good make will reliably cut off the flow.

In article , fred writes

ps: if you don't mind using a screwdriver to isolate the supply then this will do the job at lower cost:

Why two valves?

Yes, but you must use a pipe insert, in fact you should use an insert in the end of the pipe for every joint. This makes the already smaller bore of plastic pipe even smaller. As for Speedfit valves they really restrict the flow, a 22mm Speedfit valve has hole through it the same size as the ID of 15mm tube...

Both are ball valves... The isolation valve will restrict the flow, the lever operated one looks to be full bore but doesn't say it is. If this is a gravity system use the full bore type.

Because it's a long run, I want to be able to isolate it in case of problems. Also it would be a pain to have to climb up into the loft to isolate it at its start when doing some work on the tap at the other end.

I do always use inserts, that's a point about them reducing the bore though, maybe I shouldn't worry too much about the effect of the valves.

OK, thanks.

This might be a case where Hep2o pipe with its thinner and short shouldered metal inserts would be better (the pipe's more manageable too).

If it's hidden and there's plenty of space go for the long lever: easy to operate, easy to see the state. The screwdriver ones are neat and compact, but can stiffen and burr.

As others have said, compression joints are fine with Speedfit pipe as long as you use the right inserts.

Use full-bore lever valves such as

One thing which nobody else has mentioned is how to react the operating torque. If the tap simply has a piece of flexible pipe either end, there's nothing to react against if it takes a lot of torque to turn it. You either need to find a way of holding the tap itself in position, or need to use short lengths of copper pipe either side of the tap, held down by pipe clips. You can then join copper to plastic with either push-fit or compression connectors - whichever you prefer.

Yes, I'm always a bit worried by this, it'll be T-eed off some copper pipe so I guess that valve can be all copper one side at least and maybe I'll do what you say and have a short length of copper the other side as well.

Advantage of push-fit valves is you can rotate them so you can actually get at the handle. With compression the valve rotates on the pipe as you're tightening it and it's the devil's own job to get them to end up with the lever facing the way you want.

In article , YAPH writes

I've never nipped up plastic that tight, my compression joints will rotate with a middling level twist. I have assumed that this is the plas pipe rotating on the inside of the olive. No leaks yet and the olives definitely aren't recoverable on dismantling, I've tried. This is on speedfit.

hard brass ones.

All the restrictions are cumulative... Probably not a problem if this is mains pressure starting at a handful of bar but if gravity and only 1 bar to start with all the little pressure drops across each restriction soon add up.

Not if you've got two hands (and two spanners)! You hold the valve in the right orientation using one spanner on the flats on the body, and do up the compression nut with another spanner.

And it still puts a slight twist in the plastic pipe, so the valve handle ends up slightly off line. You just compensate for that halfway through the tightening.

Which is why, in my own place, I've used the copper/brass inserts - as being thinner so less accumulative restriction. For everyone else's I used the plastic ones.