Boiler banging noise - causes, dangers, and the cost to fix
If your boiler is making a banging noise it could indicate a problem with your system. The most common issues associated with a banging noise include kettling, air in the system, a faulty pump, loose pipes, or a poorly fitted boiler.
In this blog, we cover in detail all of the issues stated above that could be causing the banging, the danger posed by these issues, the average cost of repairs, and various different scenarios in which your boiler could be making loud noises.
Common causes of banging noise in boiler
Boiler Kettling
Kettling in your boiler is a common problem that can cause a variety of different noises. These noises are described differently but can sound like bubbling, gurgling, banging, or even popping noises. Kettling is caused by a buildup of limescale or other debris, normally in the heat exchanger. Kettling can easily be fixed by flushing the boiler system, which would often be done during a boiler service at your request.
Air in the boiler system
If there is air trapped in your boiler, pipes, or radiators, it’s extremely common to hear banging noises or similar coming from your system when you turn it on and off. This is often referred to as an airlock. This generally occurs when vapour is trapped in your system and is extremely common.
Faulty boiler pump
In your system there is a pump, (often also referred to as a central heating pump or circulator pump.) This pump is there to help circulate hot water from your boiler throughout your house. If your pump is malfunctioning it could result in an uneven amount of pressure or volume of water being sent throughout your system, potentially causing the banging noise you’re hearing.
Incorrect boiler size
This is quite an uncommon cause, especially if your boiler has been fitted by a gas safe engineer, but it has been cited as a potential cause for noisy boilers. If your boiler is too large for your house, it could be moving water too quickly through your system, causing potential banging noises.
Loose pipes
Loose pipes knocking or banging against each other is a common cause of noise. If your pipes are not secured properly, they can cause quite a racket. This is one of the quickest and easiest problems to fix in this list. Get yourself some new straps, brackets, foam, or piping insulation to reduce the noise in this scenario.
Faulty Thermostat
A faulty thermostat could cause your system to turn on and off frequently, causing banging noises. You can check if this is the cause of the issues by running some diagnostic tests. These include running both taps to see if cold water is coming out of both and turning on the heating to see if any heat is expelled. This may not be an issue with your boiler itself, but the thermostat.
An infographic explaining the common causes of a noisy boiler, if those problems are dangerous, and how much it costs to fix the issues.
Can the banging noise from your boiler be dangerous?
Whilst it could be a simple issue to fix, there is the potential for a banging noise in your boiler to be dangerous. In some cases, a noisy or broken boiler could be a potential fire hazard or be emitting carbon monoxide, a toxic gas.
Dangers or issues caused by a banging noise in your boiler could be:
Increased risk of carbon monoxide poisoning
If the heat exchanger of your boiler is malfunctioning it can cause the system to leak carbon monoxide into your home. Carbon monoxide is a toxic gas and is increasingly dangerous due to it being odourless and colourless. It can cause illness or death if inhaled on an ongoing basis. If you have any concerns that this may be an issue with your boiler, call a certified gas safe engineer immediately.
Fire Hazards
A gas leak in your system in some circumstances could potentially cause a fire. Having carbon fuel powering your heating system means that you have a flame-powering gas, which could be a cause of danger. The fire and safety centre list this as one of the 5 common causes of house fires.
Damage to the boiler
Alongside the above serious outcomes of damage to your boiler, ongoing malfunctions, banging noises, or limescale buildup could mean a replacement is needed. This is why a regular boiler service is imperative to keep your boiler and heating system working to its full potential.
Do not panic at the first sign of noise from your boiler. Most noises that come from your heating system are incredibly common, and if you regularly book an annual service, a majority of your boiler issues will be short-lived. If you’re concerned about the health of your boiler, you should call an experienced and registered gas safe engineer.
When should I worry about my boiler noise?
A noise coming from your boiler should not be a cause for panic or immediate concern. Diagnosing the issues with your boiler is key here, as it could be something very simple and not serious. A local gas safety engineer or plumber will typically be able to diagnose the issue causing your noisy boiler very quickly.
Boiler banging noise during ignition or when firing up
If your boiler is making a banging noise when igniting, starting, or firing up, it is commonly one of three things. Your boiler is struggling to ignite, has delayed ignition, or has a limescale buildup. All of these issues would require a certified professional to come and service your boiler, and make any repairs necessary.
Should I turn my boiler off if it’s making noise?
It’s not commonly suggested to turn your boiler off if it is making a nose that doesn’t sound right. Whilst some faults with your boiler can be serious, it’s always suggested that you contact a professional to diagnose the issue and advise you on the next best steps.
How much does it cost to fix a noisy boiler?
For trapped air in your boiler system, an engineer will often cost around £75 to £150 to come and regulate your system
For low water pressure, engineers quote on average at between £75-£150 to fix, and can normally be fixed within an hour
Removing limescale or flushing your system can cost on average between £200 to £300, dependent on the size of your house and your system type
A faulty thermostat can often be fixed within an hour and costs on average between £150 to £250 including parts and labour
