There are times when a noisy boiler is a cause for concern, so it’s important that you identify the root before it escalates into a more serious problem.
There are two main causes of a rattling boiler:
If you’ve checked the other possible sources and can’t find the culprit, you’ll need an engineer call-out.
Boiler pumps make humming noises as they operate, so it’s important to check this isn’t just it’s normal operating noise level.
Your boiler might be humming because…
Humming noises should be checked out by a boiler engineer. For issues with a boiler pump or fan, the casing would need to be taken off and this can only be done by a qualified professional.
Check the pump; it should be warm, but not hot. If it’s hot to touch, there’s likely a seized component causing your boiler to vibrate. The pump could also be set to an incorrect setting, like having it too high.
High pressure could be the culprit. Use the pressure gauge at the front of the boiler. It should be under 1.5 bar when radiators are cold. If it isn’t, you may need to reduce some of the water in the system. A rapid rise in pressure up to 3 bar indicates a fault, which a heating engineer should look at.
A vibrating boiler could also be caused by a buildup of excess sludge. This is potentially dangerous as it can cause overheating. You should definitely recruit the help of a qualified engineer.
Gurgling noises are usually caused by trapped air, and can be easily resolved by bleeding radiators.
It could also be down to low water pressure, lack of water in the header tank or a frozen condensate pipe.
Your boiler repeatedly heats up cold water, and the expansion and contraction can cause banging noises.
If you hear the banging sound a few minutes after you turn on the boiler or run hot water, it may be caused by airlocks in the central heating system. Lots of pump manufacturers fit bleed screws to their pumps, where you can release the air.
Low water flow and a loss of boiler pressure could also contribute to the problems your noisy boiler is experiencing.
Banging can also be caused by a boiler that’s overheating the water. Sometimes this can occur when limescale has built up on the heat exchanger or it could just be that your boiler is set to the wrong temperature because of a faulty thermostat.