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Noisy Boiler Giving You Headaches? Here’s Why, And What To Do Next.

Have a noisy boiler, and struggling to figure out what the problem is?

In our 5-minute guide, we’ll cover 7 reasons why your boiler could be making a noise, and how to fix the problem.

Common Noises From Boilers

If you’ve got any of the following noises coming from your boiler, we’ll explain them in detail below:

  • Whistling

  • Humming

  • Vibrating

  • Banging And Clanging

  • Clicking

  • Tapping

7 Reasons Boilers Make Noise

Here’s are the main reasons a boiler makes noise. Looking to get the issue fixed? Get a quick quote here. Or, if your problem isn’t listed, you can checkout our guide to top boiler problems.

#1 – Limescale Build Up

Limescale build up in pipes and connections to the boiler is common hard water areas. Check to see if you’re in a hard water area here.

The limescale will attach itself to boiler components, and the pipework connected to the boiler. This will create hotspots.

When steam bubbles pop, they’ll create tapping, banging and clanging noises, depending on how severe the issue is.

The Fix

Limescale is notoriously hard to remove.

You’ll need to get some central heating inhibitor, dose the system and flush the system out.

This will remove a good chunk of limescale, but limescale that’s years old, might not be removed.

Once you’ve flushed the system, fit a limescale reducer (also known as a scale reducer).

This will help to catch any limescale that passes through the system in the future, preventing further clunking and banging noises.

#2 – Central Heating Sludge Build-Up

Central heating sludge build up occurs in all areas, not just hard water areas.

As the interior of boiler components, radiators and pipework deteriorates, it breaks off into heating sludge (or attaches itself to parts in the boiler).

Sludge that’s broken off and travelling around your system will make tapping, trickling and clicking noises. That’s the particles hitting the sides of pipes and radiators.

The Fix

Luckily, heating sludge is much easier to get rid of than limescale.

  1. Dose your system with inhibitor and cleaner, to break down the sludge.
  2. Flush (hot flush for older systems that might be prone to leaks, a stronger powerflush for newer systems) the sludge from the system.
  3. Fit a boiler filter to catch heating sludge.
  4. Ask your boiler engineer to clean out the boiler filter at each service.

#3 – Low Water Flow Rate & Pressure

Low water flow and boiler’s that lose pressure could be contributing to your noisy boiler’s problems.

Much like water hammering, the sudden lack of circulation and pressure, followed by sharp boosts of pressure will create banging and clanging noises in the pipework.

The Fix

If a boiler loses pressure, it’s got a leak. You can diagnose a boiler leak and fix the problem here.

Low water flow rate could be due to the heating pump being on a low setting, or internal parts being seized.

Most pumps have a flow rate setting on the top of the pump. Increasing the flow rate, will help to stop your boiler making noises when it’s on.

#4 – Airlock In The Boiler Pump

Airlocks in central heating systems are common. If you have an airlock in your heating pump, it will be banging.

You’ll get this predominantly a few minutes after your turn on the boiler, or when running hot water.

The Fix

Quality pump manufacturers fit a bleed screw to their pumps.

You can release the air from the pump here. This will stop the boiler banging.

#5 – Blocked Or Faulty Heat Exchanger

If your boiler is making a whistling, kettling or gurgling noise, there’s a good chance that there’s an issue with the heat exchanger. A boiler that’s kettling is not a good sign.

The heat exchanger in a boiler is prone to attract limescale build-up. This creates hot spots, and therefore, the kettling and whistling sounds you are hearing.

The Fix

Try the solution we covered in #1 (heating inhibitor and a hot flush).

But, we’d recommend speaking to an engineer. A heat exchanger that has huge limescale build up on it, is most likely about to crack.

Unfortunately, these components are not particularly cheap to replace.

A heat exchanger including parts and labour (depending on the boiler) could cost as much as £500.

#6 – Ignition Failure

Is your boiler making noises, and then not working or firing up? If so, there’s a good chance you’re hearing clicking noise or a light tapping.

This is an ignition fault. The noise you’re hearing is the boiler trying to ignite, and failing.

The Fix

Have a boiler engineer come and diagnose the fault. The fault could be related to problems such as:

  • Lack of gas supply
  • Faulty ignition leads or probe

#7 – Pump Components Seized

Is your boiler making humming noises, or constantly vibrating? There’s a good chance there’s a seized part on the boiler pump.

Check the pump. It should be warm, but not hot.

If it’s hot to touch, it’s likely a seized component.

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

The Fix

As a temporary fix, tap the pump gently. This should free up the components enough to let the motor do its job, and the humming noise to stop.

But, you still need to find the cause of the problem. It’s likely the problem relates to limescale or sludge build up (see #1 and #2), and the pump needs to be cleaned.

#8 – Pipework Noises

Is the noise limited to the boiler? Or, can you hear noises coming from the central heating pipes?

The Fix

We’ve created a detailed guide to noisy central heating pipes here.

Ways To Reduce Boiler Noise

In summary, let’s cover a few things you can do to reduce boiler noises that including tapping, banging and even humming:

  1. Add central heating inhibitor, a scale reducer (in hard water areas) and a boiler filter
  2. Have a heating engineer do a hot-flush, or power flush on your heating system
  3. Check the boiler for leaks, operating pressure and water flow rate
  4. Remove airlocks in the boiler’s heating pump
  5. Inspect the heat exchanger for limescale build up
  6. Test the ignition leads and probe to see if they are faulty
  7. Assess whether the boiler pump is seized.

What’s Next?

Thanks for reading our 5-minute guide to diagnosing a noisy boiler.

Ready to get your boiler noise fixed? Get a quick quote here.

Whether your boiler is making banging, crashing, or tapping noises; I hope this has helped.

Still have questions? Add a comment below and we’ll get back to you as soon as possible.

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