Knocking / Banging when hot water switches on

[DNK]

Hi All
I recently fitted a new shower and since then, everytime my hot water kicks in to get up to the set temperature, there is a knocking / banging noise that continues until it reaches the temperature. I have read a few things online about completely draining the tank and then turning the water back on. But I have also read about switching everything on in the house, all taps, dishwasher, washing machine etc... to flush out any air. So both kind of contradict each other. Any advise would be greatly appreciated because the banging is driving the whole family and next door neighbour insane. many thanks in advance.

 

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[Chuck]

Many thanks for your help Chuck. Do you think I can rule out air in the pipes then?Cheers

I think that a banging noise that starts soon after the immersion heater comes on, and stops when it goes off, and happens when there is no water flowing, is most likely to be tied to the expansion pipe or perhaps other HW pipework close to the tank.

I wouldn't 'rule out' anything until the problem has been fixed but, to me, an airlock doesn't fit the symptoms you have described so well so it's not where I'd start.

 

[DNK]

I think that a banging noise that starts soon after the immersion heater comes on, and stops when it goes off, and happens when there is no water flowing, is most likely to be tied to the expansion pipe or perhaps other HW pipework close to the tank.

I wouldn't 'rule out' anything until the problem has been fixed but, to me, an airlock doesn't fit the symptoms you have described so well so it's not where I'd start.

Cheers chuck. On closer inspection tonight, the knocking appears to be coming from inside the boiler itself. So think I call to a local plumber is the best option Thank you so much for your help.

 

[Chuck]

Cheers chuck. On closer inspection tonight, the knocking appears to be coming from inside the boiler itself. So think I call to a local plumber is the best option Thank you so much for your help.

You have a boiler? I thought we were discussing an electric immersion heater!

Anyway, no question it's a job for a a Gas Safe Registered plumber then.

And if by 'banging' you mean something that could be a small explosion, please turn off the boiler until it's been checked.

I guess that explains why the neighbour was complaining...