Why is the hot water produced by my combi boiler sometimes cloudy?

The water from combi boilers is heated directly from the mains so the only time the water is released to the atmosphere is when it comes out of the tap. This means that during heating, the calcium bi-carbonate present in the water changes to calcium carbonate and this causes the creation of carbon dioxide which, when close up, is seen as millions of bubbles - this is not sediment, it is merely cosmetic. If you run some hot water into a glass and let it cool, it will slowly clear.

This phenomenon is more apparent in hard water areas and from boiler models with slower and/or lower flow rates.

Are you a professional? View our Professional Support Centre

Couldn't find what you were looking for?

Alternatively you can speak to a member of our team - Subject to Operating Times

Return to top