Boiler making noise? 9 Different types of boiler noise and what they mean

Key takeaways

🔊 How to fix a banging boiler noise

🔊 How to fix a gurgling boiler noise

🔊 How to fix a vibrating boiler noise

🔊 How to fix a kettling boiler noise

🔊 How to fix a rattling boiler noise

🔊 How to fix a humming boiler noise

🔊 How to fix a clicking boiler noise

🔊 How to fix a buzzing boiler noise

🔊 How to fix a whooshing boiler noise

Boilers are known to make all kinds of noises, from bangs to rattles and beyond. However, if yours has started to make a new or louder noise, it could be the start of a problem. Issues range from loose pipes to limescale, or from a faulty thermostat to insufficient water flow.

Being able to identify the noise will help you or your heating engineer to diagnose and fix the problem quickly and efficiently. Here’s a quick overview of the most common noises:

1. Why is my boiler making a banging noise?

Sounds like: A loud, repetitive banging noise coming from the inside of your boiler.

Possible causes: Either your thermostat is set to the wrong temperature, or there is a build-up of limescale inside your heat exchanger – this is more common in areas with hard water.

How to fix: A Gas Safe engineer will be able to diagnose the problem. They’ll start by checking your boiler’s thermostat; if the temperature is correct, they may need to inspect any underfloor pipes for loose screws.

If the problem originates from your heat exchanger, your engineer can perform a powerflush to remove the build-up of dirt and debris.

2. Why is my boiler making a gurgling noise?

Sounds like: Sloshing water with air bubbles being released.

Possible causes: Trapped air inside a radiator, a frozen condensate pipe, water shortage in the header compartment, or low water pressure.

Sometimes, a gargling noise is simply the sound of hot water moving inside your boiler. But if the noise gets louder or more frequent, consider consulting a heating engineer.

How to fix: Start by checking the water pressure inside your boiler. The needle inside the pressure gauge should rest comfortably in the green zone, between one and two bar. If it’s in the red area, your pressure is either too low (and will require topping up) or too high (and will require draining from a radiator or via the system’s drain-off valve).

Once your system has cooled, try bleeding your radiators to remove trapped air. Then double-check your boiler's pressure afterwards. 

Finally, check that the condensate pipe isn’t blocked, which is most common in cold weather. Any icicles should be gently melted with warm water.

If the issue hasn't been resolved, consult a Gas Safe engineer. The circulation pump may be running too quickly and should be slowed.

3. Why is my boiler making a vibrating noise?

Sounds like: An ongoing loud vibrating noise.

Possible causes: Loose screws, a blockage in the boiler flue, or an incorrect pump setting.

How to fix: If you can see any loose screws around your boiler, without removing any panelling, tighten them with the appropriate screwdriver.

If this doesn't work, check your exterior flue to see if anything is lodged inside. We recommend placing your hand over the vent to feel for air flow. If you can sense movement, there is likely no blockage, and we recommend calling a Gas Safe engineer to look inside your boiler. There may be an issue with the pump settings or even residue inside your heat exchanger, causing the hot water to overheat.

4. Why is my boiler making a kettling noise?

Sounds like: A whistling sound, like that of a gas-powered kettle. Or an aeroplane preparing to take off.

Possible causes: A build-up of lime scale, a leaky system, a faulty thermostat, a faulty or overheating boiler, or a faulty pump.

How to fix: Kettling can be a serious issue, and is often caused by a circulatory issue due to a faulty pump, or if the boiler's internal system is in poor condition. We recommend calling a Gas Safe engineer to inspect your system as soon as possible.

5. Why is my boiler making a rattling noise?

Sounds like: A metallic rattling sound, which may persist for differing lengths of time.

Possible causes: Loose bolts in your boiler or an air blockage inside radiator pipes.

How to fix: Secure any unclipped pipes or open valves in or around your boiler.

If the sound persists, try bleeding your radiators to remove any air blockages.

If you've tried both of these solutions and still can't resolve the issue, we recommend consulting a heating engineer, as you may have a faulty pump or valve.

6. Why is my boiler making a humming noise?

Sounds like: A constant humming or droning noise.

Possible causes: A loose screw, high water pressure, high pump pressure, or an issue with the boiler’s fan.

How to fix: Start by checking that your boiler's pressure is between one and two bar, and adjust accordingly if not.

Then, inspect your boiler for loose screws, valves, or pipes and secure or tighten if necessary.

Next, try reducing the speed setting on the boiler pump.

If the noise continues, there may be an issue with your boiler's fan, which will need to be inspected by a heating expert.

7. Why is my boiler making a clicking and tapping noise?

Sounds like: A series of metallic clicks or taps.

Possible cause: Ignition failure.

How to fix: You will need to call a Gas Safe engineer as there could be a problem with your property's gas supply.

8. Why is my boiler making a buzzing or whining noise?

Sounds like: An ongoing buzzing, moaning, or whining noise.

Possible cause: Worn pump bearings. 

How to fix: Please call a Gas Safe engineer immediately.

9. Why is my boiler making a whooshing noise?

Sounds like: A surge of water passing through your combi boiler.

Possible cause: A blocked circulation pump. 

How to fix: Call an engineer who can check for any blockages and diagnose and fix the problem. 

If your boiler is making noise, many of the underlying issues can be resolved quickly. If you have performed the safe checks mentioned in this article and your system is still noisy, we recommend contacting a heating professional to inspect your boiler before the problem worsens.

BOXT's engineers can visit your home as soon as the next working day when you book before 3pm. Visit this link to book your one-hour callout for a fixed price of £89, or call our friendly sales team on 0800 193 7777.