If you have a boiler making strange noises, it’s usually the result of overheating due to internal limescale or corrosion, or the insufficient flow of water.
The technical term for this issue is boiler kettling, and it refers to any kind of unwanted boiler noises, like banging, rumbling or whistling.
Most boilers aren’t silent. They usually make some sound as part of their normal operation. For example, you can usually hear the whirr of the pump or the hum of a fan. However, in some cases, the sounds are clearly out of the ordinary. This article will help you understand what’s going on if you have a noisy boiler.
Boiler making strange noises – why?
- Over time, limescale forms in the boiler’s heat exchanger. It forms in much the same way as it does over the element in your kettle.
- As the water is heated, bubbles of air become trapped underneath the limescale. The weird noises you hear are the result of these air bubbles expanding and bursting.
This process is exactly why your kettle makes that distinctive rushing sound shortly before the water boils. Unsurprisingly, there is a higher risk of this problem if you live in a hard water area.
Before spending a couple of thousand pounds on a new boiler, one solution may be to add descaling chemicals to the system, letting them act slowly, and then draining or powerflushing them out at a later date.
Boiler making funny noises – other reasons why
Poor water flow rate is another possible reason for this problem. If water flows through the heat exchanger too slowly, it picks up too much heat, and becomes hotter than it should be. This can also result in bubbling or boiling sounds. The word boiler isn’t really a very accurate term, since the water in a boiler should never actually boil.
A bad boiler installation can also cause poor flow rates and encourage the build-up of limescale and sludge. Once again, these will restrict the flow of water through the heat exchanger. A power flush may resolve the issue. Once this has been done, central heating inhibitor and descaling chemicals should be added to the system to prevent the problem from happening again.
Poor flow rates can also be caused by a faulty pump, or one whose speed setting is too low.
Blocked condensate pipe
A blocked or frozen condensate pipe can cause condensate to collect in the sump. As the boiler tries to operate despite the build-up of condensate, it may make bubbling or gurgling sounds before a fault code is triggered and the boiler stops working altogether. For more information on this fault, see the following page: Frozen condensate pipe: how to fix