Clunking Boiler
 

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[Closed] Clunking Boiler

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Is there anyone on here who understands boilers? Our boiler is set to come on 0600 every morning and at 0552 everyday it makes quite a loud a clunky noise for 5 seconds then a much quieter clunking just before 0600.

I think it is a vented system with an external expansion tank and a large water tank.

I’ve called a heating engineer and he’s been round but he seems a bit lost. Next stop is calling Vaillant but I thought I would try on here first.


 
Posted : 04/07/2021 8:10 pm
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When our boiler makes a clunky, banging noise it's usually because the water pressure in it has dropped and it needs topped up.

C.


 
Posted : 05/07/2021 7:27 am
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Could be limestone build up in that little tank, that's what ours was when it started clunking. It builds up and then breaks off. The plumber got rid of it by taking the little tank off and swilling it out with acid to clean it out. I dunno what the little tank is called btw lol, it was about the size of a small kettle.


 
Posted : 05/07/2021 8:22 am
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I think it is a vented system with an external expansion tank and a large water tank.

I thought you only needed an expansion tank with closed systems. Vented systems, with a header tank in the loft etc, don't need an expansion tank as the system is open to the atmosphere / header tank.

Persistent noise is often limescale (kettling) which is normally fixed with a clean out using Fernox DS-40 (mild acid). However, one off start of day clunking sounds more like something mechanical is having a tough time starting up eg pump is sticking etc (so basically no idea).


 
Posted : 05/07/2021 10:44 am
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Thanks for comments everyone. The heating engineer should know all this surely.


 
Posted : 05/07/2021 6:44 pm

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