tap troubles




Hope you can help. Had new bathroom fitted. Basin taps worked perfectly until new bath mixer was fitted. Then water flow from both hot and cold basin taps seemed weaker and when taps on quarter turn they reduce to a dribble. When cold water taps tuned off quickly it makes a bang/rattle which it didn't make previously.

Got a baxi combi boiler [one year old]

Bathroom fitter says water pressure is fine and taps have been fitted correctly. So any other ideas what the problem could be?

Thanks a lot,
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are the other taps ok ?
check under the basin for any isolation valves on the pipework.
the banging on the pipes can be a result of not clipped properly or the water pressure is very high.
he may of closed the isolation valves slightly to stop the banging and reduced the flow to much.
The other taps are OK. The annoying thing is that the basin taps did work perfectly and I don't think they were touched when the shower mixer was fitted so can't figure out why they suddenly stopped working properly.

Will pass on your suggestions. Thanks very much.
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Sorry, I meant I'll get my partner to have a look for the isolation valve and see about clipping the pipe to stop it rattling.

Thanks :)
Cool smiley!

Any other suggestions welcome from anyone out there.
The taps are driving me MAD!!!!!

Mixer taps can give poor flow rates compared to "standard" taps. when a standard tap is opened the washer lifts vertically off the seating by as much as 10mm allowing good flow rates through. 1/4 Turn mixers open via 2 plates sliding horizontally in different directions , the "holes" in these plates are small and can restrict the flow..but first try these options:
(edit:just read your post properly)
As the other taps ok it HAS to be either the new tap or the new connections under it.

On the end of the new mixer spout will be a strainer, which can be removed with a standard adjustable spanner, check that no debris is blocking the mesh. remove strainer and check flow minus strainer. dont worry..no chance of floodin the place.

If that is ok, check any isolation valves to the mixer..are they fully open?
then check the last 1 ft of pipes going to the mixer tap..are they standard 15mm copper pipe? or is it 10mm flexi pipes? if there is flexi pipes..are they straight? (not kinked, you kink a hose..you reduce the flow) even if the are straight..10mm flexis will allow less water through..fact!

With regard to the banging..un clipped pipes can be a cause..if the pipes to taps arent clipped..get them clipped, i doubt it is the cause though..mixers are better at shutting off than standard taps..just a small disc that only needs a 1/4 turn...if your water pressure is good..it will cause water hammer when mixer is shut..water velocity suddenly halted which sends a shocking thud back down the pipe. Something guaranteed to get rid of banging is a "15mm shock arrester" assuming the feeds are 15mmwhich can be brought from plumb centres for £35. Just fits onto a tee (its an expansion vessel the size of a cup, it absorbs the shock) best fitting it out of site but as near to the mixer as possble. or a pressure reducing valve (this is ok but flow will slow slightly..pressure and flow are two different things)cheaper option is turn the cold flow down via isloation valve..which to me is an unsatifactory trade off. Id go with the shock arrester..brill bit of kit that not many plumbers know about..or merchants to that matter.
just buy taps that have been made for the uk market.
sorry we are in low flow rate country.
Hi fingertight

Thanks for your reply. Will look into all the things you have suggested.

The basin has two separate taps which worked perfectly until the bath mixer was fitted. It just seems strange that they worked fine before so it makes me think that it can't be a problem with the taps or pipes....

But you guys definitely know more than me so really appreciate all suggestions and advice.
Well,.....I sympathise with you, and isn't it always the case that a seemingly really simple problem can often cause so much hassle and annoyance, and even more so when an, " expert ", is involved.

As far as your noise problem is concerned, there are usually two possible causes, air in the system, but I don't think that is your problem, I think your problem is what is known as water hammer, which is caused by a pressure wave in the pipes, which results in a loud bang when a tap is closed quickly, and which is a common problem which should be easy to fix by fitting an anti hammer valve, or possibly a pressure relief valve.

I will add some links below which will tell you more than any sane person would ever want or need to know about water hammer, including, in some cases, mathematical calculations, aaargh !.

" Bathroom fitter says water pressure is fine and taps have been fitted correctly. "

Hmmm, well, he would say that, wouldn't he, and, " bathroom fitter ", does not = qualified, experienced plumber and or heating engineer.

If the work was done so, " correctly ", how come the water doesn't flow properly, and there is a banging noise when you close the taps ?.

Do these people train specially to deliver these fob off lines, or does it just come naturally ?, standard British workman speak, ask him if he owns a horse and a big hat, why do you suppose there are so many TV progs about dodgy workmen ?.

Because you have a combi boiler, you don't have a hot water tank, your cold water comes directly from the mains and it is at mains pressure and it feeds your cold taps directly and it also goes directly to your boiler, your boiler then heats the hot supply and pumps it to the hot taps and radiators via the boilers own pump.

With a combi boiler, assuming that your mains stop cock is opened enough, the only time that water flow to the bathroom should be drastically reduced, is if someone turns on a tap in the kitchen, because the kitchen supply is usually the nearest point to the incoming mains water supply, so it can rob water from the bathroom supply if the kitchen taps, ( or washing machine/dishwasher ), are turned on.

So if the boilers pump is OK and if your mains pressure is OK, you should have a good water supply rate to your bathroom, I do, and I have a combi boiler, if you don't, then something is wrong, and you need to find a COMPETENT plumber, and or, heating engineer to look at your system and fix it, then give the bathroom fitter the bill.

Finding such a person is the hard part, ask everyone you know or work with if they can recommend someone, visit your local builders merchants and plumbing suppliers and ask them, see if your local council has a list of approved tradesmen.

You talk about basin taps, that means handbasin, and there is no way the water flow to the handbasin should be reduced, especially if the bath tap mixer is turned off, I assume that you meant to refer to the bath mixer tap, if you DID mean the handbasin taps, then your fitter has definitely made a hash of something.

If he was incompetent, you may have some other problems that are potentially dangerous.

Firstly, have you got a separate shower ?, because if you do, it needs to be a thermostatically controlled shower that is suitable for use with your particular make and model of boiler.

Why ?, because if it isn't, and someone turns on a kitchen tap, the cold water supply will be suddenly reduced to the shower, but the hot supply may continue to flow, albeit at a reduced rate, so there will be a risk of scalding, as the shower supply suddenly gets hotter, a thermostatically controlled shower will prevent that, provided that it is suitable for use with your boiler.

The same is true for a bath mixer tap, and for a combined bath mixer tap and shower attachment, which is why combined bath mixer taps with shower head attachments used to be illegal if fitted to a combi boiler system, but I imagine that has now changed since combi boilers have become so commonplace.

Here are some links where you should be able to get advice about this.



Also, don't forget Baxi, most of these boiler makers have technical departments that will often offer advice.


As for your mains water pressure being OK, don't be too certain, I thought mine was, it certainly seemed to be, then I got a new boiler fitted.

The engineer was recommended by the boiler manufacturer, and he was on the ball, he checked the water pressure with his meter, and said it was low, he called the water company and they arrived when he was off site, and they checked the supply and said it was OK, I knew that was
b/s, but what could I say ?.

When he came back, he got on to them again, and they couldn't get away with fobbing him off, so they had to install a new section of supply pipe which fixed the problem, so be advised.

Now, and finally, the dreaded water hammer links.









Thank you soooooo much for taking the time to give me so much advice and information. Your comments make a lot of sense to me.

Just to calrify the order of events ...
1] new sink /basin taps fitted and worked perfectly
2] a week later bath mixer fitted [which works fine]
3] on same day as bath mixer fitted, the basin taps stopped working properly and I noticed the noise when turing the cold tap off.

So could something have happened while the bath mixer was being fitted that affected the basin taps [even though they are on the other side of the room?]

I was playing around with the basin taps and they feel "tight" to me i.e. you have to turn them quite far to get a flow of water [which then reduces to nothing anyway!]. I also noticed that when the water is flowing if I put weight on the taps or push against them at a cetain angle it seems to affect the flow and in some cases it stopped the water from slowing down. Does that mean anything significant???

Thanks again for all the great information /advice and the links.
Any suggestions glasgowgas???

Would appreciate any words of wisdom :)

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