Water Hammer Problem

zebidee1

full-time-mum wrote: »

BIL took out the old dishwasher. During this process, he had to turn off the water. This may or may not be relevant to the problem.

This is maybe nothing to do with it at all.......but this sounded a bit like a situation we had last week. Our water was turned off so a tiny bit of pipe (4") could be added for our f/f connection. When it was switched on again we got the dreaded water hammer.

Plumber came out and found a very small leak (just a small drip) from a connection, tightened it up and water hammer went. His best guess was that this tiny leak was just enough to affect the pressure.

I had looked up water hammer on the net, and not one page I read mentioned a miniscule leak being a possible cause, so it does seem a bit weird.

In reality though.....connection tightened = leak stopped = hammer gone.

Maybe nothing to do with your situation at all, just thought I'd mention. :rolleyes:

trogg

Hi,

turn the stopcock fully open then turn it back a quarter of a turn.

as for the leak, there is a 'nut' just where the tap goes into the valve, is that where the leak is ?

if so, tighten this nut up (clockwise) about a quarter of a turn,

don't over tighten it or you won't be able to turn the stopcock off at a later date.

Canucklehead

trogg wrote: »

Hi,

turn the stopcock fully open then turn it back a quarter of a turn.

as for the leak, there is a 'nut' just where the tap goes into the valve, is that where the leak is ?

if so, tighten this nut up (clockwise) about a quarter of a turn,

don't over tighten it or you won't be able to turn the stopcock off at a later date.

I guess you missed post number 8?

trogg

Canucklehead wrote: »

I guess you missed post number 8?

no, just reminding the op

elliemfl

Hi, I have just seen this post and wonder if anyone could help. (plumbers?)

We have a terrible water hammer problem when we flush our toilet.
It only happens then. The only way you can stop it is to turn the bathroom tap on until the cistern has filled.

We have tried changing the pressure via the main stopc0ock but it made no difference. We did temporarily help the problem but draining the entire system and re-filling, but it only last a few days.

It's definately the toilet cistern, and not a main water tank because we don't have a header tank in this house.

We have an odd toilet valve that I haven't seen before, not the traditional round ball type thing. (it seems to be called a Torbeck valve) and our cistern is bottom entry. Pic below of what we have...

http://www.screwfix.com/prods/55211/Plumbing/Toilet-Fittings/Adjustable-Height-Bottom-Entry-Torbeck-Valve

Can anyone tell me if a different type of valve would solve the problem? Screwfix seem to have a few different types, so am wondering if that would make a difference?

Thanks in advance...
Ellie

Canucklehead

Hi

If you have had this problem from the time the Torbeck valve was fitted then ignore the following.

I'd be grateful if either the OP or the last poster could just REPLACE THE WASHER, just to satisfy my curiosity
In the case of the Torbeck there is also a filter.

If the Torbeck has made a noise from new then it's possible that the flow restrictor was not fitted in the base of it before the tap conn was done up.(Two are provided in the kit one medium pressure, one high pressure)

Corgi Guy.

elliemfl

I especially like the fact the the leaflet you link to advertises the thing as reducing water hammer, which it clearly doesn't in our case!!!

I don't know how the valve was fitted, it was already in when we bought the house, and I guess it's about 5 years old going on the age of the bathroom.

You say change the washer... where would I find this? This is probably a stupid question, but I'm no plumber I'm afraid, just a lowly French teacher!!

I have just looked at ours, its a little different to the one in the leaflet, there is no blue collar halfway up so I can't check for the flow restrictor.
I guess it must be an older model.

THanks for trying to help a plumbing eejit :rolleyes:
Ellie

Canucklehead

Hi

If you delve deeper into andrew-b's link you will find this page......http://www.opella.co.uk/Torbeck_side.htm
Open the PDF Torbeck side entry. Leaflet.
On the older bottom entry valve the restrictor goes into the threaded part at the bottom, which is the bit that sticks out of the cistern.;)

Corgi Guy.

full-time-mum

reheat wrote: »

Was it the main stopcock you turned down, or just the one to the loo cistern?

The main one that turns the water off for the entire house.

reheat wrote: »

Pretty sure it is flushing the loo which causes the problem.

The whole cysten vibrates - you can also feel it vibrating along the pipes under the floor in that room.

reheat wrote: »

The trouble with water hammer is the sound can carry through the whole water system and sound like it's originating from places it's not. It may be the real culprit is the ballvalve in the main water tank, and it sounds like it's somewhere else - the whole water system hammers once it gets going. It's very possible the main stopcock to the house (usually under the sink) is turned up a bit too high ... as others have said here.

I fairly sure we don't have a water storage tank. The both hot and cold water come off the mains. There is a hot water tank of some description in the airing cupboard but it is my understanding that inside there are 2 sets of pipes - one for the radiators and one for hot water. The hot water in the tank heats the water in these pipes.

reheat wrote: »

Must admit it's confusing you say it gets worse when you turn the water pressure down, which is why I'm wondering if it's the right one you are turning down?

Definitely the right one. I turned it down a little and the noise got a little less when I flushed the toilet and turned on the shower so I turned it down some more and got the noise when flushing the toilet alone.

reheat wrote: »

Water hammer occurs when a ballvalve bounces up and down in the water at the same frequency as the water pressure rises and falls in the pipes. The ball valve bounces up in the water closing off the valve, the pressure rises in the pipework pushing the ballvalve back down a tiny bit, the pressure falls off and the valve comes up again, and round it all goes again and again. When both are happening in sympathy you get positive feedback ... same basic mechanism as sound systems screeching and the way suspension bridges have shaken themselves to pieces! One trick is to do something with the ballvalve (edit: sorry, I mistakenly said stopcock earlier!) to damp it's movement a bit, but could be a bit risky trying if you're not plumbing inclined. The easier thing is usually to reduce the water pressure, so there's not enough power to keep it oscillating.

Do you think limescale could exacberate the problem? (changing the weight of the ball thingy).

Will have another go at turning it down at the weekend when we can work together and I don't have to keep running up and down stairs!

full-time-mum

Canucklehead wrote: »

If you get this on the main storage tank, replace the 4" float with a 6" float on the ballvalve.(It just unscrews) Adjusting the stopcock is not the answer.

Corgi Guy.

Don't think there is enough space for a larger float but I will try unscrewing it and descaling to see if that helps - desperate times and all that!