Are you worried about strange noises coming from your boiler?

We all know that boilers, refrigerators and washing machines often making a bit of noise while operating, and usually it’s easy enough to zone it out in the background.

However, the second something doesn’t sound right, we focus in on it and start to worry that something is definitely wrong.

I often get calls from worried customers about strange boiler noises, and there’s usually always a simple explanation and fix – which is why I decided there was a real call for this troubleshooting central heating blog post.

Below, I’m going to talk you through some of the strange noises that indicate there’s a problem with your boiler, and how to fix them.

Could it be dangerous?

When it comes to troubleshooting central heating, your safety is obviously our first concern, so let me put your mind at ease: Most boilers have safety precautions such as thermostats, overheat stats, pressure relief valves and oxygen depletion sensors already fitted.

So, if something serious is wrong with your boiler, it will most likely cut off and refuse to work. The chances are that if your boiler is still functioning normally whilst making strange noises, it probably won’t be dangerous.

Now, let’s take a closer look at some of the most common noises your boiler is likely to make:

Problem 1: Swooshing Noises

The Cause: This is number one on the list of strange noises for most modern combi boilers to make, and is caused by low pressure in the boiler itself.

The Fix: Check the gauge at the boiler; if it’s below 1 bar, it will need topped up using the tap and braided hose (technically known as the ‘filling loop’). Turn it about 90 degrees and watch the display climb back up to to 1.5 bar, then turn the tap off and reset the boiler.

Problem 2: Banging noises

The Cause: A broken pump can cause your boiler to make loud banging noises that make it sound as if your boiler is acting like a pressure cooker, before switching itself off with no heat to the radiators. This is because the water cannot be pumped around the system.

The Fix: Call a Gas Safe registered heating engineer who will be able to safely replace the pump.

Problem 3: Whirring/spinning noises

The Cause: If your boiler is making strange whirring or spinning noises, before cutting out and starting up again about an hour later, it could be a sign that the fan is seizing up. The sound you are hearing is caused by the fan bearings labouring to work, before eventually sticking.

The Fix: For a quick, temporary fix, you could try turning off the electrical supply, removing the boiler’s casing and spraying the spindle of the fan with WD 40. However, this might only last about a day, and you’ll have to arrange for a heating engineer to replace the fan.

Problem 4: Gurgling noises

The Cause: If you’re concerned about your boiler making lots of gurgling noises that sound like a kettle boiling, it’s probably because you have an older system with a feed and expansion tank in the attic. This is a common problem known as ‘kettling’.

The Fix: You could try putting some Fernox or Sentinel heavy duty central heating cleanser in the expansion tank and letting it run through the system for a few days. Be sure to flush the system through, thoroughly removing the cleanser before adding a good central heating inhibitor.

However, it may be cheaper to call in the experts, as not all cleansers can break down heavy built-up sludge deposits and it may be necessary to cut out and replace some pipework.

Call in the professionals

As I mentioned above, there are a couple of little tricks you can try when strange noises are coming from your boiler, however in most cases it’s more cost-effective to call in a knowledgeable engineer.

An experienced heating engineer will have seen these problems time and time again over the years, and will be able to easily diagnose and fix the problem – often saving you time, stress, bad moods and trips to the local DIY store.

There are also times when trying to fix it yourself could make things worse. I was once called to an unusual job that taxed me quite a bit as the client had done a bit of DIY without actually letting on in the beginning. The system was making terrible noises and drawing air into the system.

On inspection, it was found the pump was very shiny and new looking. It transpired the boiler had been banging and water not circulating, so the customer had purchased a new pump and replaced it himself.

All good, but the pump was now circulating banging, pumping water into the expansion tank and filling the boiler and radiators with air. It was a simple enough fix for an expert, and involved removing the pump and turning it 180 degrees, before refitting and turning the system on. It worked perfectly.

Because the pump had not been fitted correctly, water had been flowing the wrong way and pumping to the expansion tank instead of drawing from the expansion. It was a very easy mistake, but costly and stressful for someone who assumed it was an easy fix.

Conclusion

It’s easy to become concerned when you start hearing noises that are out of the ordinary for your boiler. The good news is that if your boiler is still functioning normally, it is probably NOT dangerous, as there are various safety precautions in-place.

The most common (and often unsettling) sounds boilers can make include:

• Swooshing noises

• Banging noises

• Whirring/spinning noises

• Gurgling noises

If you’re currently experiencing any of these from your boiler, I’d recommend looking at my troubleshooting central heating tips above. However, in most cases, it’s wise to call in a Gas Safe registered engineer who has experience of diagnosing and fixing these problems.

Good luck!