If your boiler is making strange noises, it could be a sign of kettling. Kettling is a term used to describe one of the noises made by a boiler, caused by lime scale build-up and can be an indicator of a fault within your system. So how do you know when your boiler is kettling and what should you do about it?
Boiler basics
To understand what kettling is, it helps to understand a little about how your boiler works. To create hot water, it heats the water through something called a heat exchanger. If you live in a hard water area, then the boiler will pick up more calcium salts, also known as lime, than in soft water areas. As the water gets hotter, these salts become insoluble and settle in the bottom of the boiler container. After a while, the flow of water is restricted by this built-up and the heat exchanger starts to get too hot. The exchanger then boils and expands, creating the kettling sound that we hear outside.
Other causes of kettling
While this is the most common reason for a boiler to make kettling sounds, it isn’t the only one. Other reasons why boilers can make such noises include chemical and mechanical issues, all of which will mean you need to call a professional to take a look at your boiler.
One cause can be the introduction of something into the system such as washing up liquid that causes foaming. An old idea was that washing up liquid made a boiler quieter but all this does is cause foaming in the boiler and make more noises! Other times, the deposits within the boiler aren’t due to hard water lime but due to corrosion debris but the effect is much the same.
There are also several mechanical causes for kettling including:
System design – if something isn’t designed right on the system, this can cause kettling. Classic examples are thermostatic radiator valves on all radiators causing the boiler to cycle rapidly and overheat. Another example is incorrectly sized and fitted open vent pipes.
Flow rate settings – if the flow rate isn’t correct then this can lead to heat dissipating back into the boiler and causing kettling.
Malfunctioning thermostat – if the thermostat on the boiler isn’t working correctly, this can lead to kettling.
Gas burner pressure – this involves the boiler being wrong set up and is most likely to happen on small systems where heat cannot dissipate.
Dealing with a kettling boiler
Working with a boiler and the heating system of the house can potentially be dangerous and should always be done by a professional – the water in the system is at boiling point, for starters. DHS offer a call out service that can be with you at the earliest possible opportunity and can conduct an assessment of the boiler to find the nature of the problem. Once it has been ascertained what the issue is, the expert heating engineer can then deal with the problem and ensure the only kettling is the one in the kitchen preparing a cup of tea.
For more information on boiler servicing and boiler repair in Bristol, please get in touch.
Unit 2 Septimus Buildings 
