Noisy Boiler

[colin711]

The problem I have is that whilst the boiler is heating up, I get banging from the pipes until at working tempter ... then the banging stops !!

Can anyone help please !!! it's keeping me awake !!!

 

[JohnD]

The banging is very likely from steam forming, then collapsing, in lime scale inside the boiler, especially if you live in a hard water area.
You can get a boiler silencing chemical from Dearborn Betz, I think it is meant to disssolve the limescale. You can also try filling the system with soft water, this will prevent new scale forming and slowly dissolve the old. I live in a hard water area and have a softener, so I have done this. you could also use a Brita drinking water filte whicb takes out calcium, but remember you have about 20 galls of water in the syst so it is a bit slow.

 

[PEDANTICVINDICTIVEMAN]

Dont do this if the heat exchanger is aluminium.

 

[JohnD]

Dont do this if the heat exchanger is aluminium.

Didn't know that, mine are cast iron. Is this a corrosion thing?

 

[colin711]

Thanks JohnD, but why does the the boiler bang only whilst it's heating up .... when at right temp (after about 5mins), the banging stops ????

 

[JohnD]

It's the fierce flames heating up the iron. The layer of limescale insulates the iron from the water to some extent, so it gets hotter than you would wish. the water on the scale boils and forms steam bubbles, then it hits the cold water and collapses, the bang is the steam bubble collapsing, I suppose like a balloon bursting. When the boiler is up to temp, the water is hot, and the flames will be cut off, so you stop getting the boil-and-collapse.

This noise is also called kettling, if you look inside an old kettle as it is coming to the boil you may hear it makes a noise (or "sings"), whereas a clean new one, or a bright saucepan, boils silently.

 

[JohnD]

the noise made by pipes expanding (getting longer) and contracting is quite different, likely to be a sort of "tickticktickticktick" and can be silenced with insulation or felt round the pipes where they rub along joists or pipe clips.