Why Is My Boiler Making Noise?


Has your boiler started making a rattling, humming, vibrating, gurgling, banging or other strange noise recently?
Why Is My Boiler Making Noise?

Has your boiler started making a rattling, humming, vibrating, gurgling, banging or other strange noise recently? There are times when a noisy boiler is a cause for concern, so you must identify the root before it escalates into a more serious problem.

Why is my boiler making a rattling noise?

There are two main causes of a rattling boiler:

  • Excess air in the system. You can get rid of it by bleeding your radiators and, as this is a simple thing to do, you won’t need to call an engineer.
  • Loose screws or components that rattle when the unit is in use. Unclipped pipe work is often the cause of this kind of noise. Try locating the source of the sound, and simply tighten any loose valves.

If you’ve checked the other possible sources and can’t find the culprit, you’ll need an engineer call-out.

Why is my boiler making a humming noise?

Boiler pumps make humming noises as they operate, so it’s important to check this isn’t just its normal operating noise level.

Your boiler might be humming because…

  • There’s a blocked flue. It’s not uncommon for this to happen, with leaves, feathers and other debris building up over time. If you place your hand near the vent, you should be able to detect a certain amount of air movement. Check this first, as it might be an easy fix.
  • The pump needs cleaning. There may be a limescale or sludge build-up.
  • There’s a malfunctioning pump moving around too much inside the casing, or moving too quickly.
  • The pressure is too high.
  • It may need a service. Having a regular boiler service can go a long way in keeping your home life running smoothly and avoiding unnecessary disturbances to your daily routine.

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.

Why is my boiler making a vibrating noise?

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 recruit the help of a qualified engineer.

Why is my boiler making a gurgling noise?

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.

Why is my boiler making a banging noise?

Your boiler repeatedly heats 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.

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PlusHeat offer extensive home emergency cover so you can protect your home (and your wallet!) when things go wrong. We offer 24/7 advice and support with boiler and central heating, plumbing, electrical and drainage cover. Contact our friendly team on 0808 164 2892. We’re here to help!