I need to replace the hot tap in my bathroom sink. The bathroom is ancient, 30+ years old, and will be replaced in the next year, so I just need something simple to keep it working until then. I've not fitted a new tap before, but I've done some research and have a couple of questions:
Assuming that the old tap is a 1/2 inch tap, do I need to buy a 1/2 inch tap, or will a modern 15m tap be OK?
From looking round on the net, a sensible option seems to be to use a flexible hose. Am I right to think I should buy a 1/2 fitting for the pipe end and, depending on the answer to Q1, a half inch or 15mm fitting for the other end?3. 3. Should I use a push or compression fitting (bearing in mind I haven't done this before)?
That's 1990, which would be metric (and not at all ancient in relative terms).
If it's pre-1970-something the pipework will be imperial.
1/2" pipe refers to the internal diameter, 15mm pipe is the external diameter. The same olives or solder fittings will probably fit both.
You can use a 22mm fitting with 3/4" pipe, so long as you use a 3/4" olive.
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The tap end will almost always be either 1/2" BSP or metric small-bore with a hose supplied to got to 1/2" BSP female.
To join two 1/2" BSP females (hose to hose) you need a nipple
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Plumbers I've used seem happy with push-fit, either JG Speedfit or Yorkshire Tectite, but I'm not sure if push-fit will work on even 3/4" imperial pipe.
I never understood why the change from imperial to metric was accompanied by a change in measuring internal versus external diameter of pipe. Or at least, why imperial denoted the inside diameter of the pipe.
You never fit anything inside a copper pipe: all soldered and compression fittings go *outside* the pipe. So it makes more sense, logically, to measure the outside diameter of the pipe, and the inside diameter of the solder/compression fittings into which the pipe fits (those two measurements should be virtually the same). It explains why 1/2" copper pipe wasn't replaced by 12 or 13 mm, but 15 mm pipe - to allow for the thickness of the wall.
But hey, this is the imperial system we were talking about: common sense and logic (eg using the base (10) that we are taught to count in), and having
*one* definition of a unit (instead of ounces troy, avoirdupois and apothecaries, and instead of having UK and US pints and gallons) don't apply to imperial. ;-)
I didn't realise that solder and compression fittings for 1/2" (nominal OD
15.9 mm) and 3/4" (nominal OD 22.2 mm) would sometimes accept 15 and 22 mm pipe respectively. A difference of 0.9 mm for 15 mm pipe is quite a large amount for an olive or solder joint to bridge.
My parents renovated an old cottage in the mid 1970s. I remember dad having to take out all the old 1/2" pipe and start again because he found that he couldn't get a water-tight seal between 1/2" pipe and 15 mm fittings, when he needed to install additional pipe - eg when the bathroom was renovated. After he'd done all the work, he found a specialist plumber that sold
1/2"-to-15 mm and 3/4"-to-22 mm converters (I can't remember whether they were compression or solder) which would have allowed him to continue using the old pipe but connect new 15 or 22 mm pipe to it.
Thanks for the responses. Thinking about it, I'm probably being optimistic in saying it's only 30 years - I'd say it's more like 50+, from the hideous bright pink bath & sink.
I've measured the pipe, it's roughly 15mm externally, which doesn't tell me whether it's imperial or metric, but does tell me it's not 3/4".
Based on the responses so far:
It's probably not safe to assume that 15mm & 1/2" are interchangeable.
Given the small difference in the size though, a new 15mm tap will fit in the hole in the sink for the existing tap, even if it is 1/2".
Given the age, my best bet for the flexible hose is probably 1/2" pipe to 15mm tap. If I'm wrong on that, it's not a large loss (about £3 from a quick look online).
Traditional taps typically have a threaded base that passes through a hole in the basin. You pass the tap through the hole (possibly with an o ring or washer of some sort between the tape base and the basin), and then fix it in place with a lock nut that screws onto the threaded base. Once fixed in place, you connect the pipes using a tap connector, which is fitted to the end of the pipe.
e.g:
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The threaded section that sticks out the bottom of the tap will be described as 1/2" BSP (British Standard Pipethread) or 3/4" BSP. Note that the sizes refer to the *internal* diameter of an iron barrel (i.e. thick walled) pipe. So the actual diameter of the thread if you measure is is quite a bit larger than the size would suggest.
Even modern taps with threaded bases will be in one of the imperial sizes above. Typically 1/2" on basins, and 3/4" on bath taps.
(some taps like monoblock mixers will use slim braided flexi hoses to connect to the pipes. These *might* terminate in a 15mm compression or push fit connector)
Tap connectors are available in compression, push fit, and solder:
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(I have shown right angled types - but straight ones are also available)
The easiest swap would be "like for like" - assuming the tap projects a similar distance below the basin, you will likely find you can simply reuse the existing tap connector. Especially of there is a bit of "give" in the pipe to allow it to be reposisitioned a bit.
If you can't get the new tap to match up with the existing tap connector, then yes you could use a flexi connector.
In the circumstances, I would go for push fit. Something like:
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The 1/2" BSP connector would screw onto the tap (with a fibre washer to make the seal). The push fit end just pushes onto the cut end of a pipe.
Note that you will need to use a pipe slice to cut the pipe and not a hacksaw since the internal rubber seals in a push fit fitting need a slightly tapered pipe end and no sharp bits, and that is difficult to do with a hacksaw. Something like:
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will do the job. Put round the pipe, and tighten the thumb wheel, spin it round the pipe a couple of times, and tighten again. Rinse and repeat until the pipe is cut.
Or you can get "automatic" versions like:;
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Just push onto the pipe and rotate in the indicated direction until the cut is done.
15mm tube is near enough 15mm measured with digital callipers. 1/2" is nearer 16mm (15.88) (external diameter)
But that is irrelevant as regards a tap connector. There's a very good chance a new tap will have the same thread as the old, and not require any alteration to the pipework.
Why? Leaking gland? Unless that shaft is very worn and tightening the gland nut and/or repacking the gland might suffice. Dripping, replace the washer, if the seat isn't cracked.
Mind you getting the cover and/or top of the tap off to do that on a
30+ year old tap could be fun and replacing the whole thing the "easy" option.
A modern tap will still be 1/2" BSP for the tap connector.
As others have said you might be lucky and the new tap will have a stem close enough in length to the old to allow it to connect to the existing pipe work.
Flexible hoses are OK 1/2" BSP tap connector one end (and new fibre wsher) and the other end I'd go for 15 mm compression.
Due to the existing pipe possibly being 1/2" I wouldn't like to say a pushfit would work or be reliable. 1/2" is I *think* slightly smaller in OD that than 15 mm.
1/2" ID. Wall thickness 0.040" x 2 = 0.58" OD = 14.723 mm ie 0.277 mm or 11 thou overall, murdering up a 15 mm fitting with 15 mm olive should take that up no problem.
Be aware that a lot of references on the web to 1/2" copper tube dimensions are for the US not UK...
3/4" pipe and 22 mm compression with 22 mm olive do NOT, BTDTGTTS. You can get 3/4" olives for 22 mm fittings that does work. 1/2" to 15 mm olives aren't available....
You will be hard pushed to find a 1/2" pipe end or 15 mm tap end. Try the otherway round. B-)
See above. Push fit are designmed to work on 15 mm OD pipe. If you have 1/2" pipe (14.723 mm OD) I suspect that might be outside the range acceptable for push fit. Compresssion can just be murdered up. B-) You will need two decent spanners for compression.
Oh and probably a basin wrench to get at the back nut to remove the old tap and fit the new one.
Connecting your new tap into the existing plumbing may be the least of your worries.... Removing the old tap after such a long time may well be problematical as the lock nut will be not only difficult to access but may be seized on. Think about how you might cut the locknut off or the tap top itself.
I am speaking from experience as I wanted to change the cold tap washer but broke the sink and ended up changing the sink, taps and drain for my trouble.
Thanks for all of the responses - much appreciated and gives me a lot more confidence to tackle the job. I hadn't appreciate that new taps are still sold in imperial.
In terms of getting the old tap off, I can see that is very likely to be a problem. Tricks I'm aware of: penetrating oil, light tap with a hammer, heat, Please let me know if there's anything else.
One quick question on that: am I likely to be better off with a fixed or adjustable basin wrench?
I think this kind is more likely to enable access:
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But it is well worth getting one of this kind:
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if you don't have one. Partly because it may work better with your particular tap and partly because it can be quite good for stopping things turning such as taps or the fixed part of fittings you are trying to undo.
Depening on what was used to seal the tap to basin penetrating oil might not have much effect on 30+ year old plumbers mait. It'll be set hard and solid. Remember the basin in porcelain, it can crack, be very gentle tapping the tap. The hole in the basin won't be perfectly round, if the plumbers mait is in the void between tap stem and sides of hole you could be trying to force round something that wants a bigger hole to rotate.
Heat, I wouldn't. OK the basin has been fired but that would have heated and cooled the whole thing fairly evenly, not sure how the glaze would take to being spot heated.
I find with adjustable almost anything is that they have a habit of adjusting themselves looser as your fiddling about gettting them onto what ever. Or loosen if you don't keep the pressure on them that is holding the setting.
Having said the above the tolerance on these fixed type basin wrenches leaves a little to be desired. Generally they are a loose fit to the back nuts but at least once fitted and held up don't "self adjust" and when rotated will grip the back nut.You can also clamp mole grips or similar to the shaft to provide a good hand grip or something gently tap.
"NY" snipped-for-privacy@privacy.invalid wrote in news:rnomds$o2q$ snipped-for-privacy@dont-email.me:
Old school emphasis was on the carrying capacity of the pipe/tube whether it be lead, copper or iron, the inner dia, new age thinking is the compatibility of the fittings, the outside dia. We now have multiple 15mm pipes/tubes in materials with different carrying capacities, plastic with thickers walls and restrictions of internal stiffeners at joints will not carry the same volumes for a given pressure drop as copper.
Your imperial pipe dims don't seem right, an imperial 3/4" olive is thicker than a 22mm olive to compensate for the _smaller_ o/d of a 3/4" pipe.
A quick search shows:
3/4" imperial, 0.846" o/d == 21.49mm, too much diff for a 22mm olive hence the availability of 3/4" olives but perhaps ok on 22mm solder but prob only on end feed with extra solder.
1/2" imperial, 0.596" o/d == 15.14 mm so basically compatible with 15mm fittings, this is readily accepted as the case
IME it took a *lot* of work with steel wool on 15mm end feed fittings to get the 1/2" pipe to go in at all. (Only applicable at the weekend when convertor ones weren't handy.)
The basic problem is that the very, very old plastic head just turns on the valve, so either the valve or the head has lost it's thread. I?ve been to my local plumbers merchant. They told me that you can?t get this type of valve anymore, photo here:
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I messaged an online plumbing store and they recommended a conversion kit:
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Unfortunately it came with no instructions and I can't find anything useful on the web. I've spent ages looking at it, but can't see how to fit it.
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So I'd given up on these attempts and decided to try and change the whole tap. I'd be very happy to be told I've missed something and there's a much easier way.
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