Banging from hot water cylinder - please help

[Deltalima]

I bought a flat recently; it’s all electric with no access to the gas network.

I had an electric central heating system installed this year. The boiler is Potterton Gold 9Kw and the water cylinder is an Elson Zircon ZD 150 Direct Unvented.

There has been banging coming from the cylinder. For ages I thought it was my downstairs neighbours being noisy, but I sure it is the cylinder. It makes loud clunking/banging noises mostly between 2am and 4am. It happens when I’m not using the system; no taps are on, no central heating on. I even turn off the immersion heater at the fuse box, and still there is banging.

It literally just woke me up and now I’m at my wits end, because I’m losing sleep.

Does anyone know what it might be? How’s the best way to fix it?

I have a video that I could upload to YouTube if that would help.

 

[Deltalima]

Here’s the video. Skip to 0:13 for the banging.

It’s actually louder in real life than on the video.

Again, any suggestions about how to resolve this, or what’s going on would be so helpful.

 

[dilalio]

Noises are never easy to diagnose... especially over this media.

Can you describe your property a bit more... how many apartments above and below etc.

If this happens only between those times and you are not using or heating ANY water, then my initial thoughts would be...

A. Incoming Water pressure increases during those “low usage” hours, for the area you live in and the noise is the pipework, under tension due to the increased pressure.

B. You have a neighbour who works a late shift and uses water at those hours which again, results in pressure changes to the incoming mains and causes some water hammer which is permeating through the shared pipework.

Fitting a pressure gauge at an appropriate location could help you identify the above as a possible cause.

The clip you posted sounds to me like pressurisation artefacts.

 

[Deltalima]

Hi dilalio

I appreciate your fast response.

My flat is two-stories and I am on the top floor. There are two flats below me; one on the first floor and the other on the ground floor.

In relation to your second point, my neighbour who lives directly below me, is unemployed and I can hear him usually, so I’m pretty sure he’s asleep when it starts. I’m not sure about my neighbour on the ground floor.

I told the guy who installed the system about it. He - in a round-about way - said: “you’ll get used to it”. Would it be worth going back to him again with your pressurisation artefacts suggestion?

Also, is fitting a pressure gauge quite a standard/inexpensive thing? And are pressurisation artefacts dangerous?

 

[dilalio]

Sealed pipework can make similar noises when nearing the set pressurisation limit... it can be down to pressure reducing valves or simple ball cocks shutting off.

I did say that the above was my “thoughts” not a definitive diagnoses.

On your video clip there is also what sounds like a clock ticking in the background and the recording levels of that are about the same as the knocking noises so, maybe you are just hypersensitive to it because you are worried that the noise indicates immediate failure of something that will cause catastrophic damage?

This is unlikely if all has been installed correctly... the direct cylinder incorporates devices to release pressure through discharge pipes in fault conditions.

Try and monitor if this happens during daytime... if only at night then, as I said, likely to be pressure increase during low demand period for the block/area.

 

[Deltalima]

Thanks dialalio.

 

[reds42]

B. You have a neighbour who works a late shift and uses water at those hours which again, results in pressure changes to the incoming mains and causes some water hammer which is permeating through the shared pipework.

Might be a neighbour running dishwasher/washing machine on off peak electricity at night causing water hammer.

Whilst I was part way through altering some plumbing in my house with pipes not yet securely fixed my washing machine casued loud water hammer when shutting off its water valve.

 

[dilalio]

Might be a neighbour running dishwasher/washing machine on off peak electricity at night causing water hammer.

Whilst I was part way through altering some plumbing in my house with pipes not yet securely fixed my washing machine casued loud water hammer when shutting off its water valve.

I covered this in my first post but yes... shift workers during off-peak times also a possible cause.