Banging noise in ensuite wall, if hot water run in house

[tpenthouse]

Hi,
Wondering if anyone can help I have an ideal classic boiler and a Megaflo Unvented Hot Water cylinder. All under 4 years old.

Lately I have been getting a banging noise behind my en-suite wall whenever a hot water tap / supply is used anywhere in the house. This banging intensity is dependent on how much the particular tap is open.

I have also found that if the banging noise occurs (e.g. wife in shower in main bathroom) I can get it to stop by opening and slowly closing the hot water tap in the ensuite. The ensuite wall is almost at the opposite end of the house where the tank is so I am bemused as to the cause.

Any help / suggestions would be great

 

[kevplumb]

plastic pipe not clipped / flexing inside wall

 

[tpenthouse]

thought about that but why always in the same location even when the hot water is not being used in that vicinity - and why does it stop if the tap is turned on and off.

 

[lee32]

it is water hammer by the sounds, basically securing the pipework should stop it. try altering the flow by reducing the inlet flow slighty if u cant access the pipe.

 

[tpenthouse]

tried that - someone suggested its the internal expansion bubble (with it being an unvented hot water tank / system) and that it needs recommissioning

 

[tpenthouse]

tried re-commissioning the system yesterday (as instructed by an unvented qualified plumber). closed mains valve opened some taps then turned the pressure release valve (at tundish) until all water poured out of the taps. Then re-opened the mains valve. Allowed the tank to refill and the water to come through the taps.

Thought all was well until tonight when the banging started again in the same place. This time the banging also continues for a few seconds after the tap is closed before ceasing.

Any thoughts??

 

[speedyuk]

I seem to have a similar problem (since past 6 weeks) and interested in finding out if it's resolved. I don't want to hijack this thread but thought perhaps it may be related.

I've noticed for me it happens when the water in the megaflo has been heated by the boiler. I can see a valve above the megaflo in-line with the hot water outlet (which says RWC 8 bar). Wonder if it's a problem with that pressure valve not being able to handle the increased pressure due to recent heating of the megaflo water. Or perhaps some limescale having built up?

I've had the system installed and running fine for 2 years

 

[tpenthouse]

Still not solved yet.
Have turned the pressure down in the water (at the mains) and
Also turned the heat that the water is heated to on the boiler

As of now the banging is not as much but still present occasionally. Have also cut a hole in the wall near where the noise is to try and have a look at the pipes - cant see anything obvious but will attach a few more clips to the pipes to be sure

 

[tpenthouse]

Hi,
Update to say issue not resolved (guys any other suggestions as this is pi**ing me off now). tried all the usual things with the mians supply, recomissioning the tank etc and still no joy. The pipe where the noise is coming from is behind my ensuite shower and from the hole in the wall it sounds as if the pipe is pulsing when the noise happens - can even fell it in the control dial of the trevi shower unit (could it be the shower control unit)

 

[saphipps]

I've been in my new house for 2-years. And, only now, the banging has started!

I find that it can be stopped by running any non-mains tap (hot of cold). I think it's something to do wth the balanced cold water supply???

Anyone got any ideas?

Is it a problem with the cold-water combination valve? What exactly does this valve do??? I'd change it if it didin't cost £90.

Thanks.

PS: The water here is very hard (I'm not talking about the ice )