Having a boiler means you are probably familiar with the sound of your pipes occasionally banging without warning, or maybe it’s the boiler. What causes them to do that and is it something to worry about? Here we shall take a look at the most likely causes and see what can be done about it
What noises can a boiler make?
- Boiler making banging noises.
- Loud vibrating noises.
- Boiler kettling.
- Boiler making noise like an aeroplane.
- Humming.
- Rattling.
- Whistling.
- Clicking or ticking.
Most common causes for a noisy boiler
- Air blockage in system including pipework
- Boiler kettling
- Overheating of water
- Faulty thermostat
- Limescale build up in the heat exchanger
- Insufficient water flow or pressure in system
A boiler system can make sudden, loud noises due to a few reasons. Boiler components and other parts of the heating system can wear out and break off into sludge. It will still be working while making the noise so you don’t think too much about it. As it moves around the system, you will hear clicking, tapping or trickling noises.
But having these noises means it should be looked at, especially when you are turning your heating on constantly for the colder months.
Noisy boiler due to air blockage in system
Trapped air is a cause of boiler whistling. One of the most common causes of banging sounds in a boiler system is if air gets into the pipes. This creates pressure changes that make loud gurgling or banging noises.
This is common in systems that have radiators and the solution is to drain all the air from your system, allowing the correct pressure to be restored. It is best to call a professional if you don’t know how to do this yourself.
Kettling in the boiler
When water becomes trapped in the boiler, it can lead it being overheated and this evaporates into steam. The steam then quickly expands to many times its original volume and so does the pressure. The sudden increase in boiler pressure can be the cause of the banging or whistling noises in your system.
If you hear recurring banging or whistling noises in the boiler like a rapidly boiling pot of water, the noise is probably coming from something called kettling. This is caused by a disruption to the flow of water, either by blockages or faulty parts causing the water to boil, steam and expand. Often the cause of kettling is a build-up of limescale or debris within the system.
This also means that the boiler cannot heat your home efficiently or you may notice less hot water coming to the taps. Build up of debris can be removed with a system flush or a chemical clean.
Call in an engineer to get this done as leaving it means the heat exchanger is a likely victim soon which is a very expensive part to replace.
It is recommended to get a magnetic filter put in once the system has been flushed. Its job is to attract the debris before it can damage your boiler and pipework system. This will also prevent banging noises in future.
Debris can occur from within the radiators, or when water is topped up or from solder from pipework etc.
If you can hear your pipes banging when you turn on a hot tap, this could be due to overheating. Check your boiler’s thermostat by turning off the boiler and cooling the system down. Once cool, turn it back on again and turn up the thermostat.
Setting your boiler to a very high temperature can overheat the water, causing steam bubbles.
Boiler noise caused by faulty thermostat
If the boiler’s thermostat is faulty, it will allow the burners to stay on longer than they should, causing the heat exchanger to overheat. And when water comes into contact with the overheated exchanger, steam bubbles are created, which then erupt and make noises as they pop.
Limescale build-up causing a banging noise in the boiler
In parts of the country that are hard water areas, the cold water mains supply will have a higher amount of limescale within it and as combi boilers take in water direct from the mains and heat it, there is a high risk of limescale build-up. If not prevented or treated, it can accumulate in the heat exchanger causing it to block up.
Boiler noise caused by water pressure or flow being too low.
When the water pressure or flow is too low, water runs over the heat exchanger slower than it should. This causes the water to overheat, giving rise to steam bubbles that erupt forcefully when they reach cooler water.
Check the pressure gauge on the boiler to see if you have low water pressure causing the gurgling noise. Usually, if the pressure gauge is showing less than 1 bar, this means the pressure is too low and will need to be increased by filling the system through the filling loop.
Is noise from the boiler or the pipes?
If you hear one loud bang when your boiler first turns on, the most likely reason is delayed ignition. Delayed ignition can be a cause of a banging in the boiler. This is a type of mini explosion and happens when your thermostat signals the boiler to start working and send gas flowing to the burners.
But, if your burners don’t ignite right away, because they are dirty or clogged, they will struggle to light resulting in gas build up in your boiler’s combustion chamber.
When the burners finally ignite, there’s already a large amount of gas sitting in the chamber, so it causes the mini explosion, which can make a banging or booming noise.
Radiator or pipes clicking or ticking?
Clicking and ticking noises can be caused by loose brackets or pipe clips. When the boiler is turned on and the hot water makes its way to the radiators, thermal expansion makes copper pipes knock against wood or concrete in the walls and floors. Heated water travelling rapidly through the pipes makes the pipes move if not clipped properly.
A frozen water supply pipe or blocked condensate (plastic) pipe – especially in winter can also be a cause of noise as build-up occurs within the system.
Checklist to fix your noisy boiler
When you hear a noise from a heating system:
- Check where the noise coming from. Upstairs or downstairs, near the boiler or near the pipes.
- Check how often it happens. Only when you turn the boiler on or regularly as the heating is on?
- Check the temperature of the water. Is it set too high?
- Check the pressure on the gauge.
- Have you checked if the pipes are securely fixed. Check the area where the noise is coming from?
- Have you bled the radiators? To get rid of trapped air.
If you have checked the above and find out that something needs fixing, call in a qualified engineer to take a look at the boiler system and get it fixed.
