The kettling noise heard from a boiler is caused when scale deposits form within the boiler heat exchanger.
These scale deposits restrict the water flow within the heat exchanger, which causes the water to become trapped and subsequently overheat, as the heat exchanger is where the water is heated.
The overheated water will then start to steam and boiler, expanding within the heat exchanger.
Other debris such as sludge can also have a kettling effect on the boiler by collecting around the heat exchanger.
Kettling reduces the efficiency of your boiler, meaning that the boiler will be more expensive to run than necessary.
The life of the boiler will be reduced, as the build up of debris and restricted flow will mean the boiler will need to work harder, putting unnecessary added stress on vital components.
Providing all safety controls are working, the boiler should turn off before any damage is caused by the overheating.
Boiler kettling can be easily fixed, and prevented.
If the scale is too extreme, a new heat exchanger may be required on the boiler. Only a Gas Safe engineer should undertake any work on the boiler.
Firstly, a Central Heating Flush will remove any scale and sludge from within the boiler, pipe work and radiators.
Once completed, a system inhibitor will be added which will reduce sludge and lime scale build up within the central heating system.
Additional measures, such as scale inhibitors can be installed into the system pipe work to reduce lime scale build up.