Cold water tank constantly making noise like it's heating water (even when it's off)

dkayuk

Hi

just wandering what could went wrong.  Around lunch time today, I happened to be in the bathroom/toilet and I heard very loud banging noises from the water tank.  Once it had settled down it started making this noise like it's constantly heating the water.  The BG water heater/cylinder is right under it.

This has been going on since 12ish today non-stop.

This is a very old system, I think possibly 35+ years old, in a small flat.

The only marking I can see is a British Gas black box to set the temperature (it's set to 60 degrees, same as it has been for many years).

The BG plumber will come Monday (I have homecare). 

Is there anything clever I can do to stop the constant noise?  I have found the tap to stop the hot water but nothing to turn off the water heater itself.   Thought there would be some kind lever to pull but nothing obvious.

Immersion heater is off (through a switch) and I am not using the boiler.  Yet the constant kettle noise is still there.

The picture I've attached shows the setup (sorry I know it looks a bit messy!)



//DK

Bendy_House

'Banging' is worrying.

A 'kettling' sound - the sizzle of a kettle heating up, or in this case, the immersion heater element - can be mistaken for the 'hisss' of a slightly letting-by ballcock. Eg, like the sound of a toilet cistern refilling - tho' in this case it would be the CWS tank. (Cold Water Storage). So, it might not be clear whether this is an immersion heater that's running, or a slightly 'on' ballcock (ie like the hiss when a tap is almost turned off.)

'Banging' is different... That is usually (always?) caused by overheating water. And the only way I can think that the hot tank can be heated to that degree - banging - is via the immersion heater. (The other way of heating the cylinder - via the gas boiler - simply won't get the tank up to the point where it's anywhere close to boiling, ie 'banging')

Soooo, just HOW hot is this cylinder? If you - carefully - touch the copper pipe that comes out the middle of the top of the hot tank, how hot is it? 'Ouch' hot? Or $%*&^%-'ell, my hand is on FIRE!

Ie - is the hot cylinder 'boiling'?

The 'black box' thing is the immersion heater. IF it's a case of the water overheating, then this will almost certainly be the culprit. And the thingy (thermostat) set to 60oC will likely be the cause - ie it isn't shutting the immersion off as it should, when 60oC has been reached.

You say the immersion heater has been turned off via a switch? Where is this switch - it doesn't appear to be in that cupboard. Does this switch have a red indicator light on it? If so, is that off too? Is there a timer on the immersion heater? Eg, does it come on automatically at night?

IF the noise IS overheating - 'kettling' - then that immersion is still on. Go to your CU and identity the immersion heater MCB. Flick that 'off'.

I wouldn't close any valves. Any you have done, reopen them - and take a photo of it to explain which one it is - post it on here.

dkayuk

hi Bendy_house

I have touched the copper pipe that comes out of top of the yellow cylinder, it feels a little hot, but not uncomfortable to touch.

There is a normal switch on a socket that I would use to turn on the immersion, and that has been OFF for years, I never use the immersion heater as it's so expensive.

Today I also turned it from the electricity box with all the switches.

Still going and here is a pic.

BTW, I also stopped the gas supply for the whole flat and it didn't make any difference.

Here's the pic.



PS: as soon as I post this, I will kill all the electricity in the flat to see if that stops the noise and post again.

dkayuk

hi again
i stopped all the electricity to the entire flat.  No difference whatsoever.
Noise is still going strong.

//DK

Note that this is a block of flats, not a house, not sure if this is relevant

Bendy_House

That's just weird!

Things we can conclude:

1) It ain't your immersion heater overheating. Phew!

2) It ain't your hot cylinder overheating. Phew!

3) er, that's about it.

Have you tried touching the black tank? That should be pretty much stone cold. Is it?

I would add that there's a very good chance that it has nothing to do with your flat at all - it's more likely coming from the flat above(?), and the sound is travelling through the pipes.

Do you know the folk in the surrounding flats? Worth having a knock to ask if they have such a noise?

The 'kettling' could still be a not-shutting-off ballcock in that black tank. Ie, it isn't kettling, but is water hissing through an almost-closed valve in there. But, you seemingly know what these sound like? Ie, 'kettling' is a 'sizzle' which fluctuates. A leaky valve is a more steady 'hissssss'. What do you reckon? Any chance of posting an audio clip somewhere we can access?

Hang on - that's a BIG CWS. Are you sure it is just supplying YOUR flat?

Bendy_House

If that CWS is warm or more, then you need to speak to your neighbs asap...

The two pipes coming out t'bottom - are they cold? The two white pipes heading up to the top - are they hot?

dkayuk

thank you so much.

The black tank is stone cold, yes.

The sound, however seems to be very loud in my tank, I haven't asked the other neighbours yet.

Not sure how this all works TBH.

Bendy_House

You and me both, pal. :-)

If the hot cylinder is just 'normal hot' but not scalding, and - more importantly - the CWS is stone cold, I don't think you have much to worry about from a safety pov.

The only options I can think of are - a neighbour has an issue. Or, your ballcock is letting by, so you'll be losing a steady stream of water out your overflow pipe outside.

Tomorrow - or tonight if you have a bright torch - check outside on the wall, and see if there's a sticky-out pipe end that's running water.

The 'banging' is a worry, tho' - that just ain't right.

Unless - lol - it's neighbour's tank wot's letting by, and that was them banging on the side to try and close off the ballcock!

Time to pay some visits...?

dkayuk

interestingly enough, there were some workmen on our street this morning and they "temporarily" turned off my neighbour's water supply, I wonder if they did something to my water supply.

The other thing that I noticed is that before all this happened, everytime I would flash the toilet or use a tap etc, all this water would flow into the tank, you would actually hear it filling up very quickly.  

This is no longer happening, all I get is droplets coming in to the tahnk and the constant sound I mentioned.  

Many thanks for your help.

//DK

Bendy_House

That CWS is probably supplying every tap, shower and bath in your flat, hot and cold, except your kitchen cold. So, yes, every time you run any tap (except K-C), that tank will refill.

Anyhoo, please remember to come back and put us out of our misery when the plumber comes

Section62

dkayuk said:

interestingly enough, there were some workmen on our street this morning and they "temporarily" turned off my neighbour's water supply, I wonder if they did something to my water supply.

The other thing that I noticed is that before all this happened, everytime I would flash the toilet or use a tap etc, all this water would flow into the tank, you would actually hear it filling up very quickly.  

This is no longer happening, all I get is droplets coming in to the tahnk and the constant sound I mentioned.

Is the cold water storage tank running dry then, if you aren't getting a decent flow of water into it?

You can get banging noises with plastic cold water tanks if the supply pipework isn't attached to something solid - the plastic wall of the tank can flex a bit which causes the ball valve to open slightly, the flow of water in turn causes movement of the tank and pipework.  If the situation is just right it can set up 'resonance' which can cause all kinds of strange noises.

A system which was previously quiet could start making noises due to resonance if there was a change such as an increase or decrease in the mains supply pressure.  So someone doing work on the pipes in the street could have affected the pressure you are getting and triggered a problem you didn't have before.

However, if all you are getting is a few droplets of water (never full flow) then it isn't likely to be resonance - there needs to be a reasonable flow/pressure for the conditions to be right.  It would normally only happen when the tank is nearly full and the ball valve has reached the point where it is close to stopping the flow.

If the ball valve is fully open and you still only get a few droplets that would suggest some kind of blockage - it is plausible the work being done in the street has introduced some dirt into the pipes, or dislodged some scale or sludge, and that is now causing a partial blockage within your plumbing.  Dirt/scale getting into valves is another possible cause of noise, but not necessarily what I'd call 'banging'.