Help needed - loud noises upstairs when taps on

2 Sep 2012
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United Kingdom
We've recently had a new combi system installed (Worcester Hi-Flow 550cvi), replacing an old cynlinder/tank system, and are now experiencing really loud noises under the floor upstairs when some of the taps in the house are on. The noise happens only with the taps on, and not all taps create it - we hear it with the hot and cold kitchen taps (but not fforrm a filter tap also in kitchen basin) and the hot tap only in the downstairs bathroom. Also happens when the upstaris bathroom sink mixer tap is on - no issues running bath or showers or other upstairs bathroom sink.

It's so loud that we don't use the kitchen tap when someone is asleep - not a long term option! We have also had several leaks over the last three weeks which is very worrying. We hae just moved into this house so we dont' know if the noise existed before (left message wiht previous owners).

The plumber who fitted the new system (great chackatrade ratings) says he has never expereinced this before and does not know what the problem is. He originally decided it was becasue the water pressure was too high form the mains (the water was ridiculously powerful, flying over the basins when taps on full), so he turned it down at the mains - noise disappeared but only for a few hours. After 4 days put the pressure back up. Now he wants to take up the floor upstairs to investigate the pipes but as we've just had the floors sanded and restored we are not keen to do this just as an experiment when he already admits he doens't know what's wrong. I'd really like to get a second opinion at this point or someone who recognises the issue with some good investigative leads not requiring major surgery which we can try first!

Thanks in advance for any help, much appreciated.
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the pipes need to be tightly clamped to the wall to prevent them vibrating

any plumber knows that

start with the easy ones that you can get at. later you will have to do the ones under the floors. Use proper screws into the brickwork with plasplugs.

The sort with the fold-over clip top grip tightly.
More than likely pipes not clipped sufficiently now that you have installed a combi the hot is at mains pressure aswell instead of gravity fed.
Thanks so much for your replies JohnD and Armo74.

What confuses me if it's pipes vibrating - why would it happen with only some taps - for example both cold and hot in kitchen but only hot in downstairs bathroom not cold? And wouldn't taking the mains pressure right down be likely to lessen the noise then - as presumably the hot water pressure would be more like it had been with previous system? We had really bad pressure for those few days but no lessening in noise. Noise is only in one specific part of the house, and that's an area where we can't easily get to the pipes (so should we really need to start clipping all others?).

the plumber mentioned 'there may be small ball piping' (seems to be his main theory right now prior to getting access to pipes) or 'lots of elbows' and that the noise sounds as if something is obstructing the flow of water. I have googled small ball piping this but got nothing relevant really (lots of rude things!) - any views on this would be also much appreciated.

There is also occassionally some screeching and clanking noises when the shower is on but not coming from the area with the loud noise.

Thanks again!!
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wouldn't have thought there would be any obstructions otherwise you would notice the difference in flowrates. some pipes are probably clipped and some more than likely are not. Do you have any dripping tap's? Or cistern valves?
Its small bore rather than ball, I imagine....make sure any isolator valves are fully open - they make a hell of a din if they are even a tiny bit on the closed side.
John :)
wouldn't have thought there would be any obstructions otherwise you would notice the difference in pressure and flowrates. some pipes are probably clipped and some more than likely are not. Do you have any dripping tap's? Or cistern valves?

That's what I thought. No dripping taps that i can tell. not sure how to check for cistern valves. There have been 5 seperate leaks since the new system was installed. 1. A pump under the bath broke and water gushed through the kitchen ceiling light fixture (pump was then decommissioned) but there is still water that pools and seeps our from under the bath now. 2. upstairs sink hot pipe was dripping at a join and wrecked the cabinet under the sink (plumber fixed this since), 3. en suite shower (tiling cracks so just unfortunate conincidence?) 4. under bath pooling 5. stopcock downstairs is dripping - only noticed this yesterday, under the downstairs sink so this cabinet is wrecked now too.
Google "water hammer"

Plumber hasn't mentioned this but I had heard of it but from what I've read this is not the case, no hammering sound - sound is just when tap is on (instantly starts and instantly stops) and is a like a loud engine noise which is constant and continuous - no banging or hammering.
Its small bore rather than ball, I imagine....make sure any isolator valves are fully open - they make a hell of a din if they are even a tiny bit on the closed side.
John :)

Thanks Burnerman :) that seems to make much more sense! I will try to work this out for myself and definitely mention also.
Inn case anyone is still monitoring this thread... I have some updates and I'd really love some additional opinions.

2 more plumbers have observed the load noise since. All agree that it sounds as though water is being restricted, and with 6 bars from the main this may be due to a something in the specific pipe that's noisy, or may be possible to resolve with appropriate pressure reduction before the floors must come up...

Original plumber installed 1/2 inch pressure reducing gauges to the cold up pipe and the hot up pipe, effectively as an experiment as he fully admits to not having a clue what's wrong... but this was only (done) - [edited to clarify] several weeks after the new system was installed, and following the 5 leaks.

In a second opinion visit today a new plumber declared this to be ineffective (pointless) as the cold main tees off before the pressure reducer and that instead of two pressure reducers on the cold and hot pipes there needs to be just one, it needs to be 3/4 inch, and it needs to be after the mains stopcock but before the mains tees off. Does this seem correct to you guys? SOunds logical...

Also, some other things he mentioned - he said they'd done beautiful pipe work but unfathomably not even lagged the new copper piping in the garage (not heated out there).

Also mentioned there was about £600 worth of copper piping which was a waste of money as plastic would have been fine. Any views on this? And that there should have been new valves put on any of the legacy rads (only 2 were replaced).

We also have continuing problems wiht the rads - some thumping out heat some cold. Original plumber came to balance them at my request (having read up here) and this sorted it our for a day or so then it went back to what it was.

We are very wary and I'd love to get confidence to let this new guy have a go but am worried that if two plumbers both do work on it then we could be in a tangle if we end up having to fall back on original plumbers insurance to claim for damage resulting form the five leaks....?! Not even sure about how we might go about all this.

Really appreciate any help or advice from anyone, pretty desperate.
Pursue the installer who did the job. Put your complaints in writing asking him to rectify. If he refuses to do more, then put in writing again that you will get someone else to carry out the work, and will invoice him for the cost, following up through the courts. Small claims will handle this cheaply.
Before you proceed, however, what exactly did you ask him to do? Whose idea was it to re-use the original system? Did he offer to or did he recommend replacing all? If your problems are down to faulty components ( old taps and radiators) you are probably going to have to pay for rectification.
Thank you oilhead,

The original installer(s) completely replaced the previous gravity system (just before we moved in so we never expereinced the old one - it was 20+ years old). He installed a new combi boiler (removed cylinder and decommissioned water storage tank in loft). He replaced 2 rads but said that the others were fine and replacements were not needed, so we still have those.

I think your advice makes a lot of sense, we need to pursue this with the original installer before incurring further costs. But I have actually lost faith in his ability to fix this based on what the third opinion guy has said about his work - so I'm keen to get someone else to do it as it will otherwise drag on and on. The tricky part is that the original guys maintain that the noise problem was not introduced as a result of the change to combi but that it must have always been like that - though the previous owners swear there was no noise. And the original guys don't take responsibility for the leaks. Therefore it will get accrimonious if I try to invoice him for the costs of getting someone to do more work, and to be honest I am still not sure if he really is liable, as I'm finding it hard to know who is right in all this... Hence the desire to get some further opinions... getting some views on the following things would really help work out who is the more credible...!! I dont' want to pay out more cash to someone else for work that might not be needed, and/or that I might not be able to claim back. But if I pressure the original guy to do it he might not agree and/or be capable and will want to charge me at this stage... Am I in the right if I start mentioning the small claims court now?

1. Is it standard to fit a pressure reducer while converting to combi in a high pressure area (6 bar)? The guy today seems to think so... Is it clearly wrong to overlook this and a sign that they were out of their depth that they didn't? Or is it more of a 'nice to have' depending on the situation? The 5 leaks we have had seem to me to suggest that we needed one!

2. When fitting a PRV should it only evey be fitted to the mains feeding into the boiler? They fitted 2 PRVs, one to the cold up and one to the hot up pipes. Third opinion guy said this was pointless, as the cold had already teed off before the PRV and there was no need for one on the hot too if it had been in the right place...

3. The original guys used copper piping throughout and did not lag the extensive piping in the unheated garage. Third opinion guy said copper was really expensive and uneceesary and it was a school boy error not to lag pipes in garage as they could easily freeze and burst or leak...

Thanks in advance once again for any help or advice, all gratefully recieved
Firstly, the previous owners would say there was no problem wouldn't they?
Next, if the leaks are on pipework that the installer put in, then how can he not take responsibility.
Next, a pressure reducing valve may be required. I don't work on gas, so I'm not sure on this boiler, but one or two oil manufacturers recommend reducing mains to 3 bar. Usually this is done before the boiler, but if you have mixer showers, then differential may be a problem, so whole house reduction is advisable, but would usually be done with one valve. Has anyone tried reducing the cold flow? I have encountered problems with too great a flow, similar to your symptoms. Pressure is different to volume, turn down the stop tap slightly and see if your noise goes away.
Finally, there are plenty of posts about copper v plastic. plastic is cheaper, and easier to install, but can look terrible, and is susceptible to attack by rodents. Also joints can be susceptible to failure, especially if high pressures are involved. Lagging in vulnerable areas is a necessity.

It is easy to pick flies in someone else's work. When asked, I generally will not offer a strong opinion.
you could fit a mini expansion vessel on the cold main (do you have a water mtr/non return valve?)

check there are no "dead legs" where air is trapped when they cut out hot water pipes around the old cylinder.

the taps may be "jumping" can you re washer them?

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