Boilers

What is sludge made from?

Sludge is a buildup of undissolved components in the water of your heating system. 

The main component, magnetite, is formed from iron rust when water and oxygen interact with steel pipes and radiators, but it also contains limescale – deposits that form from hard water.


Dirt and general system grime are also found within central heating sludge. Left untreated, sludge and all the various components it contains causes poor water quality and ultimately, could damage your boiler. 


60% of boiler breakdowns are caused by sludge in the system. Having a magnetic filter fitted on your boiler captures many of these particles, preventing them from building up inside your boiler and protecting it from an unexpected and unwanted breakdown.

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Help keep your heating working as it should with a Baxi service. We offer servicing for boilers, filters, cylinders, air source heat pumps and more.

Related FAQs

Should I turn off my boiler in the summer?

Instead of turning off your boiler completely during the summer, when you likely have less need for heating, you can use Holiday Mode to ensure it works at a low level and prevent parts from seizing up later on in the year when you have greater need. You can also set your boiler to only heat your water and not your radiators.

Is a condensing boiler a combi boiler? 

Most modern combi boilers are condensing models. This means the heat and gases that escape through the flue pipe are captured and reused for efficiency.

Why is my external condensate pipe freezing?

Condensate pipes can freeze due to extremely low temperatures or ice building up on the pipe, which will need clearing in order to unction effectively. Insulating your pipe can prevent this from happening.

Why should I get the water in my central heating system cleaned?

It’s important to have the water in your central heating system cleaned regularly to prevent sludge buildup, which can lead to blocked pipes and ultimately, cause breakdowns. Repairs needed as a result of sludge are not covered by Baxi warranties.  

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