Plumbing fittings questions ?

[Wuffles]

Of course they should be 15mm. (I was thinking 12mm threaded = 12mm pipe. Tosh.) As Wuffles link or get push fits. You should be able to get them with inbuilt isolators.

Isolators can go kaput to though, so minimise risk and go for separates

You can't have enough flexi pipe IMO, you can route it out of the way of "stuff" that accumulates under sinks.

And, my final comment is don't overtighten a 1/2" flexi onto an isolator, no need, just a bit more than hand tight is enough when there's a rubber washer in there.

All of the above is based on "face palm" experience.

 

[Lons]

It's dead easy, I've fitted hundreds and not a single leak, don't see what all the fuss is about tbh.

If you use the copper tails which come with the monoblock then no problem just carefully bend by hand to avoid fouling the cabinet, the copper is soft so pretty easy, as said though make sure they are tight at the tap end and don't allow to turn when making the connections into main supplies. These tails are usually 10 or 12mm and many terminate at 15mm so you can connect straight to existing pipework but if not then you will need 10mm or 12mm to 15mm adapter, freely available and then 15mm iso valves which are required under current regs. I usually replace the tails with flexis however for speed and ease of installation, they're cheap enough!

Note that it's better to fit full bore iso valves if you have low water pressure and standard hot water system or you'll restrict the flow even further with valves which have only 10mm bore, not a problem with a combi system. Also be careful when buying a tap to make sure it suits the system you have, e.g. fitting a high pressure tap into a system with low water pressure and you'll get a trickle, low pressure tap into a combi system will reduce the life of the tap. Most taps state minimum water pressure required but also be aware that some of those figures can be a bit optimistic.

cheers
Bob

 

[mseries]

Lons, the copper tails are 15mm at the plain end and M12 at the threaded (tap) end.

Here is a view of the existing plumbing showing the tails to the current tap and their bends. The grey corrugated hose is the washer waste and the smaller grey hose the washer cold water feed.

the new installation will only be slightly different with the relative position of the tap and bowl being different.


Here is a more general shot, the black tube is the sink overflow and the think black cable is the plug remote control. The grey tube is the washer cold feed. The red isolator is the unused washer hot and the washer cold is behind the p trap. The black tube obscures the join between the tap tails and the feeds, you can just see the copper corrosion and the flux stains. Those marks are much worse on the backside of the pipes,

So, if you feel like it chaps, tell me how you would do this. Remember there will be new sink unit so the bowl and waste will be in slightly different positions. I can cut the end panel for access if I need to.

 

[Lons]

Just as I said Mseries.

Are the new tails the same as existing (terminate at 15mm ) or haven't you bought the tap yet?

Current regs dictate that both hot and cold supply must have an isolation valve fitted for future servicing but a good idea in any event.
What I would do is cut the existing 15mm feed pipes below the soldered joints to get to good clean area which you'll need to clean up with wire wool, the secret of good joints is clean properly! Fit iso valves at that point and then just make up between that and the new tails. If you stick the isos on first then the water to the rest of the house can be turned back on before you fit the new sink, means the family don't have to cross their legs. :wink:

If you feel you can't manipulate pipe then you could use plastic or buy a couple of 15mm x 15mm flexible connectors which commonly are 300mm long. If you buy with speedfit pushfit ends it's even easier
So: On end of the flexi fits on end of new tail then bend gently to line up with old pipe, fit a length of 15mm pipe in to "out" end of iso valve up to end of flexi and push on - simple as that!

Cr*p sketch as I did it quickly in publisher but hope it shows what I mean
http://www.screwfix.com/search?search=tap+tails
http://www.toolstation.com/search?searchstr=tap+tails

 

[RogerS]

One point to bear in mind but you already might be aware of it is that many monobloc taps are designed to work on high water pressure - as comes out of a combi, for example. (and assuming that you actually have any mains water pressure unlike us!). Trying to use these taps on a traditional cold-water tank/hot water tank system means a trickle out the end of the tap.

 

[mseries]

Thanks everyone particularly Lons, your diagram is good enough to convey your thoughts. I don't think there is enough vertical room for your design though. I quickly measured up last night, just by sticking my tape measure up those tails (!!) and those T junctions are about 320mm from the underside of the sink unit so this is why I was contemplating flexi tails connected either to the iso or to a short 15mm pipe like you proscribe. I am not sure the new tails will not foul the cabinet side if I don't bend them.

My tails are the same as the existing, flared to 15mm and would make an easy task to fit if I could bend them properly. They are probably about 300 mm in length. So would the pros cold bend them by hand ? Would they insert a spring (would a spring work with flare pipe ?

I really appreciate the help from those with more experience that I have. Thank you.

 

[Lons]

Thanks everyone particularly Lons, your diagram is good enough to convey your thoughts. I don't think there is enough vertical room for your design though. I quickly measured up last night, just by sticking my tape measure up those tails (!!) and those T junctions are about 320mm from the underside of the sink unit so this is why I was contemplating flexi tails connected either to the iso or to a short 15mm pipe like you proscribe. I am not sure the new tails will not foul the cabinet side if I don't bend them.

My tails are the same as the existing, flared to 15mm and would make an easy task to fit if I could bend them properly. They are probably about 300 mm in length. So would the pros cold bend them by hand ? Would they insert a spring (would a spring work with flare pipe ?

I really appreciate the help from those with more experience that I have. Thank you.

Just bend carefully by hand, easy as the copper is soft, just be carefull not to kink them. You must fit to the tap before bending or will find it very difficult, so fit both tails and lower through tje tap hole and bend as necessary. Alternatively as you say, buy a couple of flexi tails instead which don't need any bending, still fit to tap first though.
You could chop out the T junc for the unused H/W washer feed as I don't think any new machines are hot feed these days BTW

Roger has highlighted what I said earlier about tap pressure and I'll say it again also as you will be VERY disappointed if you fit a high pressure tap into a low pressure system. Additionally on a mixer tap you can get unequal pressure between mains and hot which causes problems as modern taps don't have seperate channels.

Good luck with it, you'll find it easier to do than you think - now the wastes - that can be a different matter! :wink: :lol:

PS: ISO valves are useful if you need to control flow BTW, just turn down a little to balance the flows.

 

[mseries]

My taps are labelled for low pressure systems so I think I'll be OK there, it's something I checked when learning about all this, I appreciate you point it out though, this thread will be a useful record for others who might be embarking on this.

Earlier in the thread there was some discussion of connecting the flexis to the isos. I did intend to do this using a flexi tail with a 1/2" BSP threaded end. Both DiscoStu and Lons advised using a short 15mm pipe to connect the flexi with compression fitting to the iso, again with it's compression fitting. Is this considered a less likely to leak joint ? Another questoin regarding compresison fittings, some plumbers seem to use Boss White or it's equivalent for potable water around the pipe under the olive, some don't. What do you guys do ?

 

[Wuffles]

Earlier in the thread there was some discussion of connecting the flexis to the isos. I did intend to do this using a flexi tail with a 1/2" BSP threaded end. Both DiscoStu and Lons advised using a short 15mm pipe to connect the flexi with compression fitting to the iso, again with it's compression fitting. Is this considered a less likely to leak joint ?

No. Makes it easier when under a sink trying to tighten a joint that requires less tightening too.

 

[Lons]

Earlier in the thread there was some discussion of connecting the flexis to the isos. I did intend to do this using a flexi tail with a 1/2" BSP threaded end. Both DiscoStu and Lons advised using a short 15mm pipe to connect the flexi with compression fitting to the iso, again with it's compression fitting. Is this considered a less likely to leak joint ? Another questoin regarding compresison fittings, some plumbers seem to use Boss White or it's equivalent for potable water around the pipe under the olive, some don't. What do you guys do ?

You can do it either way without problems, very much depends on how much wiggle room you have. I've done it both ways but whichever you do be careful not to twist the flexi as you tighten (or use push fit which is even easier). I personally wouldn't use boss white, PTFE tape works well.

I advised fitting the iso valves to the existing pipework first so you could get the house water back on but if that isn't an issue it's better to fit to the tails then no danger of twisting the flexis.

Push fits these days are very reliable btw, just as with any joint inspect the pipe and make sure no cuts and is clean. The only thing I'd add about push fits is you should cut the pipe with a cutter not a hacksaw to ensure a good joint, you can pick up a cutter for a few quid.

 

[Wuffles]

I was taught not to use ptfe tape on a joint containing an olive, ptfe is for joints where it's a bare metal to bare metal connection, tails into a radiator for example. You won't need it where a joint contains a rubber washer either, in the case of the flexi to the isolator.

Plus, it's less messing about in what is going to be a tight space that resembles a game of 3D Twister.

 

[Lons]

I was taught not to use ptfe tape on a joint containing an olive, ptfe is for joints where it's a bare metal to bare metal connection, tails into a radiator for example. You won't need it where a joint contains a rubber washer either, in the case of the flexi to the isolator.

Plus, it's less messing about in what is going to be a tight space that resembles a game of 3D Twister.

Hmm... of course you're right as it's the soft copper olive which makes the seal but using PTFE on the threads makes it easier to thread on the nut as it acts as a lubricant.
It should never go on to the olive. I always use on the threads though and never had a problem with any of my fittings. Practice of course means that I don't play twister games with it either. :lol:

It's easy to forget that if a novice and you don't know then you don't know and to take it for granted when posting, sorry for that!

 

[RogerS]

I was taught not to use ptfe tape on a joint containing an olive, ptfe is for joints where it's a bare metal to bare metal connection, tails into a radiator for example. You won't need it where a joint contains a rubber washer either, in the case of the flexi to the isolator.

Plus, it's less messing about in what is going to be a tight space that resembles a game of 3D Twister.

Hmm... of course you're right as it's the soft copper olive which makes the seal but using PTFE on the threads makes it easier to thread on the nut as it acts as a lubricant.
It should never go on to the olive. I always use on the threads though and never had a problem with any of my fittings. Practice of course means that I don't play twister games with it either. :lol:

It's easy to forget that if a novice and you don't know then you don't know and to take it for granted when posting, sorry for that!

Why don't you recommend putting the PTFE tape round the olive? Just curious.

 

[Wuffles]

I was taught not to use ptfe tape on a joint containing an olive, ptfe is for joints where it's a bare metal to bare metal connection, tails into a radiator for example. You won't need it where a joint contains a rubber washer either, in the case of the flexi to the isolator.

Plus, it's less messing about in what is going to be a tight space that resembles a game of 3D Twister.

Hmm... of course you're right as it's the soft copper olive which makes the seal but using PTFE on the threads makes it easier to thread on the nut as it acts as a lubricant.
It should never go on to the olive. I always use on the threads though and never had a problem with any of my fittings. Practice of course means that I don't play twister games with it either. :lol:

It's easy to forget that if a novice and you don't know then you don't know and to take it for granted when posting, sorry for that!

Why don't you recommend putting the PTFE tape round the olive? Just curious.

The olive is to be squidged to take up the slack between the joints. It can be squidged a couple of times if you need to take the joint apart again, but there's no need for ptfe. Some plumbers put white boss under the olive, but the ptfe is a different type of helper for helping on a different type of joint.

That was a ramble, can you tell.

 

[blackrodd]

PTFE tape is sold as a thread tape to seal the thread on joints, taps and fittings for water and some gasses, oxygen etc
When either repairing or remaking an old compression joint or a compression joint in an awkward place then I'll seal the olive as well, as after all it is all metal to metal.
I've been caught out on the odd weeping joints, but 1 is too many, I prefer endfeed fittings.
Rodders

 

[Wuffles]

Soft metal to harder metal. Perhaps I should have been more specific.

Just to reiterate, I was taught not to use ptfe on joints with an olive in. You can use a compound on them if you like, but if the pipe is clean then you probably won't need to, the olive will suffice.

 

[Lons]

What Wuffles said.

PTFE tape itself is not a sealant, it is a very slippery material and actually difficult to glue or stick. It's often wrongly described as thread sealant when actually it acts as a lubricant for the threads. However in doing that it allows the nut to screw up easily and more tightly to effect a better seal as well as making future removal easier and cleaner than compound sealant.
Putting PTFE tape on an olive does no good, is not advised and potentially could stop the soft copper olive sealing fully against the hard copper tube / brass fitting.

I'm not a plumber but made it my business to learn and as a small builder have fitted hundreds of kitchens and bathrooms as well as a few c/h systems and a hell of a lot of rads.
My early background is however in the plastics industry and ptfe sheet, block and rod was one of our product ranges.

 

[Ped82]

I work as a gas fitter and central heating installer . On new pipe PTFE tape is not needed on the olive but doesn't harm to do it . However when connecting onto older pipes it is recommended to either use a jointing compound or wrap some PTFE around the olive (not threads)

 

[Phil Pascoe]

I always understood it was used on the olive (as above, no real need on new fittings) or mating surfaces and not the threads as it can stop the nut doing up properly, the exceptions being in situations that don't arise in plumbing where the thread itself has to seal not just pull a seal tight.

 

[Lons]

I always understood it was used on the olive (as above, no real need on new fittings) or mating surfaces and not the threads as it can stop the nut doing up properly, the exceptions being in situations that don't arise in plumbing where the thread itself has to seal not just pull a seal tight.

If you google the question (I've just done it) Phil you'll find loads of info, especially on the plumber forums. I've never been on those before and it's quite entertaining.

It's definitely a thread tape not meant for olives though and if you put on the recommended 3 turns it eases the threads rather than restricts them, as I said, ptfe is a lubricant in this application.

We had an interesting application 30 odd years ago when in Northumberland there was a huge machine nicknamed Big Geordie used to excavate coal for a large open cast site. The machine was struggling to turn due to friction and we supplied very large PTFE panels for it to slide on which it then managed like a skater on ice. :lol: