Worcester Bosch 28i boiler banging noise

powerful_Rogue

Hi everyone,

Moved into the house in December 2020 and ever since then there has been a banging noise from the boiler. It's so loud, especially at night it scares the dog! To us humans, it's just very frustrating!

Had British Gas out twice, they have checked the boiler and can find nothing wrong with it, so just wondering if anyone else has had a similar issue? No idea what causes it, at a guess, it's when the boiler is cold, has to do something and then makes the noise when shutting down.

I've managed to record a 25 second video of it. At the start, i'm running the hot water. You hear the boiler spring into life and do it's thing. At 20 seconds, the boiler starts to shut down and that's when the 4 clunking noises start. It's one of those noises that seems to seem louder round the rest of the house.

Any help or ideas appreciated!

British Gas the last time they came out said to keep a log, to see if there is a pattern, but struggling so far as it seems a bit random. The boiler is a Worcester Bosch 28i Junior.

https://www.youtube.com/watch?v=yKYYQcZrOOk

NSG666

Is the boiler pressure ok? 1 bar or in the green zone (when cold) depending on gauge type. Does it do it when the heating is on or just when you are running hot water?

powerful_Rogue

NSG666 said:

Is the boiler pressure ok? 1 bar or in the green zone (when cold) depending on gauge type. Does it do it when the heating is on or just when you are running hot water?

Boiler pressure is fine. During the winter we noticed it a lot as the heating was going on and off. However it's very intermittent. Can happen after you've run the hot water tap, or can just happen for no apparent cause. I'm sitting here now by myself as the other half is at work and it's done it a couple of times in the last few hours - no hot water being used and heating off. Really is a mystery!

NSG666

Ok does the boiler have a ECO button and if so is it glowing green? How old is the boiler?

powerful_Rogue

NSG666 said:

Ok does the boiler have a ECO button and if so is it glowing green? How old is the boiler?

It's got an ECO button, but it's not been activated and is unlit.

Jeepers_Creepers

Try emailing WB and include a link to your vid. Tell them you've had BG out twice and they're stumped as to the cause - ie it ain't anything 'obvious'.

[Deleted User]

I don’t rate Worcester Bosch boilers that highly. I have one in a new build and it has had its issues. That said, I have found Worcester Bosch’s engineers to be excellent. They have the build parameters for their various boiler models on computer and they can run boiler compliance checks. So far, I have had the fan; heat exchanger and syphon changed on a boiler which is less than 3 years old.

NSG666

The ECO button controls hot water pre-heat. At the moment the boiler will fire up every now and again to keep the water hot ready for when you turn a hot tap on. If you press the button to make the green light come on it will switch it off so the noise shouldn't occur unless heating on or hot water run. Not a cure but should eliminate some of the random banging.

How old is the boiler? Tap the gauge to make sure it's not stuck.

When you run the hot tap and it starts banging does the water run cold(er) or stay constant?

NSG666

Is the boiler upstairs or downstairs, if you have a towel radiator can you bleed it of air and/or the rest of the upstairs rads.

powerful_Rogue

Thank you everyone for your replies so far, really appreciated. I've just sent an email off to Worcester Bosch explaining the issue along with a link to the video - so fingers crossed!

Boiler pressure is absoutely fine. British Gas carried out a variety of tests, also checked for any gunk etc, everything passed. They said the boiler, despite being 10 years old is in top working order - apart from the bangs which they have no idea about!

The boiler is downstairs in the kitchen. Three bedroom house and we do have a towel rail. The heating hasn't been on for probably a few months now due to the nice weather, so it's just the hot water we're using.

When I run the hot water, it comes out nice and hot. Turn the hot water off and shortly after, when the boiler seems to be shutting down, that's when the clunking happens. Well, that when i've caught it! No idea why it happens when the heating/ hot water isn't being used!

neilmcl

Sounds mechanical to me, possibly a valve sticking when opening/closing. Could it be a dodgy diverter valve on it's way out? You'd need to open up the service flap to have a closer look where the noise is coming from.