It’s that time of year again – households will be turning the heating back on as summer is now a distant memory and the temperatures are beginning to drop, especially in the evenings.

But if you notice unusual sounds coming from your boiler over the next few months, you probably won’t be alone.

It comes as new research has revealed the most common boiler sounds households face.

However, if there’s a whistling, banging or even an alarm going off, don’t panic as we have some expert advice from Andy Kerr, founder and CEO at BOXT.

Below, the boiler specialist has outlined the issues associated with these noises - and the sounds you shouldn't ignore.

Whistling, hissing or high-pitched noise (sounds like a kettle boiling)

One cause of a noisy boiler could be kettling, which happens when the flow of water through the boiler slows down, causing the water to be overheated and reach boiling point; this is when you can hear a kettling noise.

A lot of the time this can be a result of circulatory issues which means the water isn't being pumped or moving around the system effectively. This could point towards a faulty pump and or central heating system issues.

Kettling can be a serious problem that should be looked at by a Gas Safe engineer, but common causes include:

  • Limescale build-up
  • A leaking boiler or system with the incorrect amount of water in it
  • A faulty thermostat, causing the boiler to overheat
  • Faulty pump

Five Ways to Stay Warm Without Central Heating

Knocking

If you're hearing a clicking or tapping noise, it could be that your boiler is struggling to fire up. One potential cause for this is ignition failure. In this scenario, it’s not something you should try and resolve yourself, and instead need to call a Gas Safe engineer as it could be related to the gas supply to your property.

Gurgling, dripping or bubbling (sounds like running water)

While there are other causes, for the most part, a gurgling noise is caused by trapped air in your radiator. Sometimes, the gurgling sound coming from your boiler is just the hot water moving, so there’s no reason to worry. However, if the sound is persistent and happens more frequently, it’s best to take a quick look at the following:

  • Bleed the radiator: the gurgling sound could be stemming from an appliance associated with the boiler, such as a radiator. Once you have bled the radiator, check the boiler pressure and top it up if required. A drop in boiler pressure can lead to further issues. If the noises continue, the issue resides elsewhere.
  • Check the water pressure: low water pressure could be causing the gurgling noise. Take a look at the pressure gauge in your boiler cupboard, if the dial is in the red section the pressure is too low, and your boiler needs repressurising.
  • Check for a frozen condensate pipe: this often occurs during really cold weather, when outdoor pipes can freeze. Gently defrost the pipe with warm water to resolve this. 

Have you turned your heating back on yet?Have you turned your heating back on yet? (Image: Getty Images) If the problem persists, there could be something else wrong with the boiler. Speak to a Gas Safe registered engineer who will be able to help tackle the situation.

Banging sounds

A loud banging noise can come from limescale buildup inside your heat exchanger, a faulty boiler thermostat, or it could be something as simple as your thermostat being set incorrectly.

You might want to call a heating engineer who can check the temperatures of your flow and return pipes to check for overheating, and also check your boiler thermostat is set to its correct temperature. If either of the above is not causing the issue, they may need to access the pipework under your flooring to check it is clipped and supported correctly.

A Gas Safe registered engineer can also determine if the problem is coming from your system circulation heat exchanger, in that case, you may need a central heating system flush to fix the problem if it is a result of a buildup of magnetite, debris or dirt.

Is it cheaper to keep the heating on low all day?

Buzzing sounds

A buzzing sound from your boiler can be worrying and the best course of action is to seek help from a professional. Numerous issues could cause a buzzing sound, from electrical components failing, to a pump sticking. If you can hear your boiler making a buzzing sound, or it sounds like it's moaning at you, you should listen to it.

Essentially, the whining noise is your boiler asking for help. It means it needs to get fixed immediately, and you must call a professional to do it.

Recommended reading:

Whooshing (sounds like a washing machine)

Whooshing noises are especially prevalent in combi boilers. These noises coming from your boiler are usually made by a blocked circulation pump or trapped air in your system.

For this sound, you should get in touch with an engineer, who can check for any blockages or trapped air and diagnose the problem.

Alarm sound

If there is an alarm sound coming from your boiler it’s usually a signal that something is not quite right. Common causes of this are low water pressure, a faulty thermostat and blockages. Troubleshoot your boiler by checking the water pressure and the thermostat, if these are in working order and the beeping sounds persist, contact a Gas Safe registered engineer.