How to Fix Noise in Central Heating Pipes

The boiler is the main part of a central heating system. When heating is on, the boiler has to do multiple tasks, including heating the water and pumping it to radiators and taps. Additionally, there is also an ignition system. Combined together, the boilers produce sounds such as soft humming, clicking, and subtle creaking or ticking, especially when heating is on. A gentle whooshing sound is also produced when the burner ignites.

But when the central heating system makes loud, unusual, and strange sounds, like banging, gurgling, bubbling, screeching, whistling, vibrating, rattling, or consistent humming noises, it indicates something is wrong. Many of these noises are not associated with the boiler itself; instead, they are related to central heating pipes. Such noises can be noticed under the floor and in the walls, where this pipe network runs. These noises are noticeably louder during the colder months, as the boiler has to work harder to heat the home. But if these sounds are abnormally loud and persistent, it might indicate an underlying problem that needs immediate attention to avoid potential damage.

In this guide, we will break down the most common reasons for unusually noisy central heating pipework and how to fix these noises.

Common Reasons for Unusual Sounds In The Central Heating Pipework And How To Fix Them

The common reasons for unusual noises in the central heating pipework vary depending on the type of sound. Unusual sounds in the pipework of a central heating system can be categorized as follows:

1.       Banging or knocking sounds.

2.       Bubbling or gurgling sounds.

3.       Hissing or whistling sounds.

4.       Clicking or ticking sounds.

5.       Vibration or humming sounds.

There are different causes that result in each of the above types of sounds:

·        Banging or Knocking Sounds

Areas where hard water is supplied often experience limescale buildup in boiler components, especially the heat exchanger. Limescale can accumulate anywhere across the central heating pipe network. It results in overheating. When the boiler overheats, the water is converted into steam inside the system. These steam bubbles cause banging or knocking sounds. As limescale builds up, the likelihood of loud banging increases. Additionally, the limescale buildup can also cause tapping, rattling, and gurgling sounds.

How To Fix It?

The problem of limescale buildup or sludge accumulation can be fixed by:

·         Power-flushing the system: It removes limescale, sludge, and debris from the entire pipework. This is considered the most effective method for fixing banging or knocking sounds.

·         Using a chemical inhibitor: This method is not as effective for immediate removal of sludge or limescale, but it is a good option for preventing such buildup in the long run.

·         Using Lime Descaling Chemicals: This is another useful method for removing limescale buildup from the system, though less effective than power flushing.

IMPORTANT – If the banging or knocking sounds cannot be fixed by any of the above methods or the problem reoccurs after a short time, it might be something serious, for which you may need the services of a Gas Safe registered engineer.

·        Gurgling or Bubbling Sounds – In Pipes or Radiators

While gurgling or bubbling sounds can sometimes occur due to sludge or limescale accumulation, the main cause is air trapped in the pipework or radiators. Usually, it happens after topping up the water pressure or refilling the system. Another reason behind trapped air in the system is the existence of small leaks somewhere in the pipework.

How To Fix It?

·         Radiator Bleeding: The best way to remove trapped air from the system is to bleed the radiators. It is quite easy, and almost every homeowner is familiar with it. It can be done as follows:

o   To start with, turn off the heating.

o   Open the bleed valve with the radiator key.

o   Wait for the trapped air to escape.

o   Wait until the water starts flowing steadily from the radiator.

o   Close the valve and turn on the heating.

·         Repressurize the System: If the boiler pressure drops below 1.0 bar, repressurize the system using the filling loop.

·        Hissing or Whistling Sounds

The common reasons behind a hissing or whistling sound emerging from the pipework might be one of the following:

·         Water is flowing faster than normal.

·         Some valves are partially closed, meaning they are not fully open for some reason, especially after maintenance work.

·         The flow of water is restricted due to lime scale buildup or sludge accumulation.

How To Fix It?

·         Adjust Pump Speed: If the water is flowing too quickly, reduce the pump speed if the boiler has this adjustment setting. Most boilers provide the ability to adjust the pump speed.

·         Open Valves Fully: Check radiator valves to ensure they are fully opened.

·         Check For Blockages: If the water flow is being restricted due to sludge, power flushing the system might be a good option fix hissing or gurgling sounds.

·        Ticking or Clicking Sounds

The metallic components, especially the pipes, tend to expand when heated water passes through them. Under normal circumstances, it is just a routine matter. But if the sounds are more frequent and louder, it indicates that something is wrong with the brackets holding the pipes, which results in excessive movement and causes them to rub against walls, brackets, or even the floorboard.

How To Fix It?

·         Check the Firmness of Pipe Fittings: If the pipes are not firmly fitted due to loose brackets or other reasons, there is a high risk of excessive movement, especially when heated. Ensure that all brackets and clips are tight enough to hold the pipe firmly.

·         Insulate The Pipes: Ensure they are properly insulated. Using pipe lagging is a useful solution to reduce friction between pipes, thereby reducing clicking sounds.

·         Create Clearance: If the pipes are not properly placed along walls or floors, there is a strong possibility they will create ticking sounds. Ensure they are tightly placed.

·        Vibration or Humming Sounds

If the central heating pipes are making humming or vibrating sounds, it is likely that the pipework is not firmly installed. Such sounds are often caused by a faulty pump or very high water pressure. This situation might be quite disturbing and annoying. If left unattended for a long time, it may also cause serious physical damage to the central heating system.

How To Fix It?

·         Check the firmness of brackets: Check the pipe brackets to ensure they are tightly secured. If any are loose, replace them with tight brackets to prevent the pipes from becoming loose.

·         Check Pump Speed: If the boiler has pump speed settings, adjust them to the appropriate speed.

·         System Balance Required: Sometimes, a system imbalance can cause humming or vibrating sounds. If that is the case, balancing of radiators might help, which can be done as follows:

o   Turn off the central heating system.

o   Wait for the radiators to cool.

o   Fully open all the radiator valves.

o   Turn on the heating.

o   Adjust the lock shield valve, located opposite the radiator valve. The lock shield valve on the radiators near the boiler should be slightly closed, whereas the radiators farther from the boiler should have the valve fully open. Doing so will balance heat distribution across the system and reduce noise.

Preventive Measures

·         Ensure timely repairs and annual servicing.

·         Install a magnetic filter to protect the system from debris.

·         Add a chemical inhibitor to avoid limescale and sludge buildup.

·         Ensure proper insulation of pipework.

·         Monitor boiler pressure regularly to keep it within the recommended limits.

FAQs

1.     What is the reason my heating system pipes are making noise?

It usually occurs due to the natural thermal expansion of metals. When the heated water passes through the metallic pipes, they tend to expand, causing unusual noise.

2.     Is the unusually noisy heating system dangerous?

Not necessarily, it is quite normal if the system produces some noise. Even if the noise is unusually louder, it may indicate some underlying problems, but it may not be dangerous; it should be fixed at the earliest.

3.     Can power flushing the system reduce the noise?

Yes, in the majority of cases, power flushing the system can fix the noises caused by limescale, sludge, or debris.

4.     Can I ignore small clicking sounds?

Yes, it's mostly harmless, especially if the sound is small and occasional. If it is more frequent and louder, it must be fixed to avoid further damage.

5.     When should I bleed radiators?

Radiator bleeding should be done at least once a year. But if there are gurgling sounds, it should be done immediately.

Conclusion

Heating systems use boilers, which are fitted with multiple internal metallic and mechanical components, as well as metallic pipework, which produce different sounds. If the sounds are not very loud and occur only occasionally, it is just normal. But if the sounds are quite loud and persistent, it indicates underlying issues, especially with the heating pipework or the pump speed settings.

So, if there are vibrating, humming, hissing, gurgling, banging, or clicking sounds emerging from the boiler or pipework that are becoming more frequent and louder, they need immediate attention. If these sounds are left unattended for a prolonged period, it may result in some serious physical damage not only to the heating system but also to the property.

In most cases, these sounds can be fixed easily without calling a professional. But if the problem persists or reoccurs more frequently, it is time to call a Gas Safe-registered engineer to thoroughly check and fix the actual issue.