Water hammer?

[Jonzjob]

Any idea how a shower head can cause a water hammer in the hot water pipes?

A while back we bought a new shower head. A slim version. It was OK for a while until it started to start a very slight water hammer when we were running the hot through to the shower. That dissapeared as soon as any cold was mixed in. It gradually got more obvious until this evening I was having a shower and instead of the slight sound and the pulsing pressure variation there was a violent hammer if there was any hot water flowing. "Golly gosh" said I as I was very wet and couldn't get anything but bleedin cold!! I had to get a spanner, change the head, not mine, for the one over the bath and the hammer vanished. Put the other one back on and the hammer occured.

So, now we have an expensive shower head that we can't use! Any ideas what the reason is folks [8-)]

[Théière]

From many many miles away you're asking something but taking a guess, something internal on a tap or mixer bar is loose but one shower head flows more than the other so has a dampening effect. The one that flows the most allows the loose part to fluctuate and produce the hydraulic hammering.

[Jonzjob]

Unfortunately TP, that is the exact opposite. The shower head that causes the problem is a small head, adjustable, but small.

The old head is adjustable from 'strip the skin' to 'gentle rain' without adjusting the flow and doesn't give any problem. The other is adjustable and what ever it is set to causes the hammer.

I have just been and changed the heads again to the culprit and at first there was no sign of the hammer, but it started quite gently and increased. I didn't let it go very far. A flodded loft isn't a good idea me-thinks?? The original head was put back and it's as smooth a silk.

Why me?[8-)]

[Théière]

[quote user="Théière"]From many many miles away you're asking something but taking a guess, something internal on a tap or mixer bar is loose but one shower head flows more than the other so has a dampening effect. The one that flows the most allows the loose part to fluctuate and produce the hydraulic hammering.

[/quote]

Or of course the exact opposite [:D]  Hmm, then the lower flow is restricting some part and the shuttle/piston in the mixing valve is wobbling back and forth possibly, either way a moveable part is oscillating when it shouldn't caused by you changing the shower head so best not to change the shower head [I]

[Jonzjob]

Ah, yes, but when SWMBO suggests I obey [blink][blink][:-))]

But, then again, if there's oscilating shuttle/piston bits in your mixing valve and they are wobbling to boot then it may mean a new anti wobble shuttle/piston assembly.

Then SWMBO can have a new head on the end of the pipe and it won't be mine [:-))]

My brain cell 'urts [:'(] All this high tech after me bed time and I ain't 'ad me medication neiver [8-)]

[Théière]

Yes indeedy, something as significant as a perished/damage O ring maybe but dare you take it apart [:-))]

[Jonzjob]

TP, it's software things that go to bits when I touch them. If I can hit it wiv a 'ammer I can fix it, unless I can't [8-)]

It isn't quite so dramatique to turn water off in this house, because the bathroom/toilets are on a seperate shutoff to the kitchen/laundry room. So it makes things a lot easier..

[Lehaut]

Do you have a thermostatic control shower mixer? Could it be the head causes a problem in the valve system in there. Could you alter the size of the holes in the new head with a drill bit?

[Jonzjob]

It's just a straight forward mixer and it has got to have been there since the house was built in 1982..

I think that I have 2 choices?

1. to leave the old head there and use the new one on the mixer on the bath

2. to strip and examine the internals (of the tap, not me [:-))] ) or replace it?

[Gluestick]

Jonz: Water Hammer can only be caused by something setting up some form of flow restriction, which in terms of logic, annoys some other part of a chain of events

Simple example: I have a couple of ageing TRVs on the CH; and if turned down from full flow, the jumper in the TRV bounces on its seat and causes awesome hammer in the CH feed circuit.Therefore, unless there is some faulty component in the new shower head, perhaps it is a wearing thermostatic capsule, plus the new shower head is more restrictive to flow than the old unit.Thermostatic controlled adjustable shower valves are quite agricultural: just a wax pellet which expands as temperature rises.

From an old thread a view of a typical valve dismantled.Here:

[Gluestick]

Jonz:

A further thought.

Try connecting the new hose to the original mixer (They are nearly all standard sizes) and experiment with the settings: i.e. fully on, full hot/full cold.

If no water hammer, then it has to be caused by the shower head.

Does the new feed hose have an inbuilt "Non-Return Valve"? Some do.

[Jonzjob]

As far as I can remember it is the same hose and no NRV in it Gluey.

After a chat with SWMBO it looks as if I will be fitting a new theromstatique jobbie in the near future. The most pressing job at the mo is sorting out the dammed pine processionary caterpillars that have started appearing in the traps I made [:-))] That's a different thread though.

[Théière]

[quote user="Gluestick"]Jonz:

A further thought.

Try connecting the new hose to the original mixer (They are nearly all standard sizes) and experiment with the settings: i.e. fully on, full hot/full cold.

If no water hammer, then it has to be caused by the shower head.

Does the new feed hose have an inbuilt "Non-Return Valve"? Some do.

[/quote]

Good point about the non return valve  It will place a restriction on the flow, should damp the hammer but maybe setting up an issue elsewhere. I didn't see that the hose had been replaced but that maybe just me skimming over.  It's a bit of a puzzler as loose parts normally cause vibrations rather than hammer. Worth turning on a tap elsewhere to reduce the pressure in the system and running the tests as well.  I had to replace a bath/shower combo because it created water hammer as the screws were too corroded to get it apart and time is money, customer was happy it stopped. The hammer happened when the kitchen tap was turned on, some 5m from the bathroom. Previous plumbers fitted a new kitchen sink tap.  The issue was loose worn part inside the bath tap/shower diverter.

[Jonzjob]

Definately no NRV as I have just removed the hose and blew down both ways [:-))] not at the same time though? I also did the complete swap combination, apart from the hoses, and there is now no sign of the hammer. Stil going to change the mixer though. So thank you one an all for your time and info [:D]

We haven't had good experiences on the couple of times in Brickodepot Q so we tend towards Richardsons. More expensive maybe, but preferable to nous. Ta for the link though. It's given me an idea of what to look for..

[Quillan]

Mods Hat ON

Thanks guys all sorted, carry on.

Mods Hat OFF

[Quillan]

[quote user="Jonzjob"]
We haven't had good experiences on the couple of times in Bricodepot Q so we tend towards Richardsons. More expensive maybe, but preferable to nous. Ta for the link though. It's given me an idea of what to look for.
[/quote]

Have to speak in their defence on this one. All our taps have been bought from BricoDepot and apart from one which has a cosmetic problem the rest have been OK for over ten years now. As I said at that price if it fails even after five years it has only cost you 4€ a year which is nothing and they only take two minutes to replace.

One tip if I may learnt the hard way from experience. When you take the old one off make sure the thread and the front face is super clean but don't use abrasive paper of a file on the front face. A wire brush is OK round the thread. When you do up the nuts do them finger tight finished with a very light 'nip' on the spanner. Turn the water back on and if it leaks just a tiny 'nip' at a time. They have a rubber washer that has some metal gauze attached to stop sediment entering the tap. If you 'swing' on the spanner it deforms the rubber washer and it can leak even more, the more you swing the more it leaks till the rubber washer tears and disintigrates. Cheap or expensive they are all the same at this point so gently, gently. If you have plumbing pipe thread paste you can put a light coat on the thread that comes out the wall but I have only had to do this once. Hope that helps.

[Gluestick]

This thread has caused me to recall an interesting French component name: anti bélier, or literally, anti Billy Goat!

Stops water hammer: which is simply hydraulic shock. Mainly since fluids are fundamentally un-compressable, whereas gases are ,of course.

However, and that said, something MUST be causing the effect: and as I stated previously, it is invariably a tap, valve of whatever, where the jumper is oscillating violently from Go-Stop and repeating at the identical frequency as the water hammer effect. Loose metal pipework accentuates the effect by vibrating in sympathy with the frequency of the oscillation.

Now, if you really want a headache, Jonz............

See here:

A nice bit of maths to send you to sleep..................

[:D]

[Gluestick]

[quote user="Quillan"] When you do up the nuts do them finger tight finished with a very light 'nip' on the spanner. Turn the water back on and if it leaks just a tiny 'nip' at a time. They have a rubber washer that has some metal gauze attached to stop sediment entering the tap. If you 'swing' on the spanner it deforms the rubber washer and it can leak even more, the more you swing the more it leaks till the rubber washer tears and disintigrates. Cheap or expensive they are all the same at this point so gently, gently. If you have plumbing pipe thread paste you can put a light coat on the thread that comes out the wall but I have only had to do this once. Hope that helps.[/quote]

Much agree, Q. So many times people over-tighten fittings. And sparking plugs in ally heads...............

I have found the Fernox plumbing sealer excellent: must be left for a few hours to go off.

Keep a fresh tube in la belle and one in the UK.

[Chancer]

The real danger of a leak, one that is hidden and will be catastrophic before you realise it is there is hidden behind the mixer valve fixings in the form of those eccentric 1/2" to 3/4" BSP adaptors used to cope with any pitch error or out of level of the fixed plumbing.

If used with plumbing sealant even French, with or without filasse, fibre or rubber washers all it takes is one degree of movement when you tighten the mixer valve for a leak to occur hidden from view behind the carrelage and which will infiltrate and slowly destroy the wall or cloison all the while causing you damp, mould and odour problems.

The only thing that I have found that will give me half a chance is to use a Loctite or equivalent anaerobic hard setting pipe sealant.

[Jonzjob]

Well, took the plunge, not literally you understand, and bought a thermo mixer, and got change from 300€, quite a lot as a matter of fact!! Got it from Lepaire in Carcassonne and it's so very nice that I lash out with a shower every month or so. well, only dirty people wash init [:-))]

The fitting was the case of unscrewing the old one at the nut connectors and screwing the new one in place. About 10 mins if I take getting the spanner to do it!!

Magique job and ta for the heads up about it folks!!

[Gluestick]

Thanks for letting us know, Jonz.

Glad all is now OK.

Personally, I would still want to know the reason for this; that's just my ever-questioning mind, I guess!

[I]

[Jonzjob]

As a 'it it wiv a 'ammer eng I always worked on two principles. 1. If it ain't broke, don't mend it and 2. if all else fails read the instructions [8-)]

As long as it did gone with the change then I work on the principle that what came off was the reason.. Init already?[:D]