A guide on boiler kettling for landlords

Maintaining your property’s boiler is critical as a landlord to guarantee that your renters have access to heating and hot water but boilers are unfortunately susceptible to a number of problems.

One of those problems is a condition known as boiler kettling which some landlords may or may not have heard of but essentially, boiler kettling is a loud rumbling or pounding sound made by your boiler when it’s turned on. 

This noise is not just inconvenient, especially if you have tenants who are complaining of the noise, but it also indicates a major condition that must be addressed that could have safety concerns for those living in the property.

This is why it is very important that boiler kettling is addressed as soon as you suspect it or hear the noises associated with the problem. You don’t want to put those living in a property at risk by ignoring it.

We’ll explain all you need to know about boiler kettling in this article which includes what causes it, how to fix it, and whether or not your boiler is at risk of exploding. 

Hopefully, you’ll have a better grasp of how to maintain your boiler and keep your tenants safe and comfortable in their homes and you can find more information about this here.

a boiler that has kettled

What is boiler kettling?

Boiler kettling is where there is a fault in the boiler that causes the boiler to think the water is at a lower temperature than it is so the water continues to be heated up and eventually there is an explosion or something major that occurs, damaging the boiler.

This is not always the case and it is possible to have boiler kettling for months and ignore it, but because of the dramatic consequences if you leave this problem untreated, you should always opt for a solution sooner rather than later.

How do you know that it is boiler kettling and not another problem?

The sound produced by a kettling boiler is detectable as a loud banging and the noise is sometimes characterised as a rumbling, slamming, or knocking sound being produced from the boiler, similar to that of a boiling kettle. 

When the heating system or hot water is turned on, you should not hear any noise at all apart from maybe some softer noises as water moves around the heating system.

If you’re still not sure about boiler kettling and what this may mean for your heating system then you should become more familiar with your system and how it works or just hire a gas safety engineer for a gas safety check.

If you have landlord boiler cover then you shouldn’t have to worry about costs either and simply calling the insurance provider will allow you to gain access to gas safety exercise without additional costs

What is the cause of boiler kettling?

There are various ways that a boiler can start kettling including a leak, simply overheating due to a variety of reasons or also a buildup of limescale which can happen in any device that heats up water.

Depending on the quality of your boiler and the amount you use it, it could be more or less likely that any of these problems occur.

A leak in your boiler

If you have a leak in your boiler it could make additional noises to the banging that usually occurs. Listen out for a whittling or gurgling of water if you’re not sure and also check for any water around the boiler. Unfortunately, finding the leak can be difficult because it may be located in difficult-to-find areas near your boiler. However, it’s critical to find the leak as soon as possible because it could be the result of poor installation in the past.

You don’t want to discover a leak too late where the water from the boiler is already spilling out and causing you to repair any damages to the walls and ceiling in a property.

How to solve a leak in your boiler

If you notice any leaks in your heating system, you should have a qualified engineer inspect it and whatever the cause of the leaks, an expert will be able to locate them and repair the problem. 

While it may be tempting to try to do the work yourself, keep in mind that you may end up violating the terms of your warranty, especially if you have insurance in place like landlord boiler cover. 

To ensure your safety and the quick resolution of a leaky boiler, proceed with caution and speak to a professional. Unless of course you know what you’re doing and the leak in the boiler can be obviously fixed.

a man fixing boiler kettling

A boiler could be overheating

Boiler problems can be aggravating, and if your boiler keeps shutting down, kettling noises may not be the only source of the problem as overheating boilers may start to be temperamental and cut out.

As boilers get older, they may end up with the thermometer in them becoming old and faulty which means the temperature in the boiler cannot be accurately tracked, resulting in the boiler cutting off because the water is, in fact, too hot.

On the other hand, it could be the case that the boiler water is not heating up at all because the thermometer thinks the water in the boiler is already hot.

This is a harder issue to fix when it comes to boilers and you may have to buy a new boiler altogether in some cases.

How to solve a boiler overheating

If your boiler is producing an unusual noise and you believe it is due to overheating, the first thing you should do is consult the handbook for your boiler and thermostat to see if there are any troubleshooting measures you can take. 

Boiler kettling should not occur if your boiler is in good working order so if it’s very old and beyond repair, you should start shopping for a replacement. 

There is a buildup of limescale

A buildup of limescale around the heat exchanger is one probable cause of overheating. This occurs when the water has high quantities of calcium and other minerals, which is typical in hard water locations. If you need a new boiler and reside in a hard water location, you have two choices. You may either buy a whole-house water softening system or ask the technician to add a hard water filter. But bear in mind that the latter must be replaced every 3-5 years.

What should you do to fix a kettling boiler?

If you do decide to replace your boiler, be sure it has a dependable heat exchanger. X

Viessmann boilers, for example, employ stainless steel Inox-Radial heat exchangers, which are extremely resistant to corrosion and endure longer than many other boilers on the market.

If you can identify that the cause of the boiler kettling is mineral deposits on the heat exchanger, there are numerous things you may take to address the issue. 

One alternative is to flush the system, which removes any rust or limescale buildup that may be obstructing water flow.

A liquid inhibitor can also be added to the system to assist prevent additional corrosion and safeguard various materials such as steel, copper, brass, and aluminium. 

Another option is to use a noise reducer, which slowly dissolves the limescale buildup and reduces the kettling noise produced by the boiler. 

A magnetic filter may also be used to remove both magnetic and non-magnetic dirt particles from your central heating system. The Spirotrap MB3 Magnetic Filter is one of the better alternatives available and is regularly used in our setups.

If you are unsure what is causing the problem or believe that there is a mechanical issue, such as petrol burner pressure or a design error, it is preferable to see an expert.

a pipe that has boiler kettling

How can you fix the noise that comes with a kettling boiler?

If you know that the noise coming from a boiler is due to kettling then the first thing you should do is make sure you are attempting to resolve the problem with a new boiler or bringing round a professional.

However, sometimes you simply need to dull the noise in a boiler so you can reduce the disruption in your home, especially if you are trying to get on with other things or fall asleep and the noise is disrupting you.

In order to reduce the noise you can attempt to cover the boiler or the piping of the boiler with towels or some form of insulation to dampen the noise. Nonetheless, if you suspect that the boiler is kettling due to overheating then you may not want to do this

Is it possible for boilers to explode?

Although kettling sounds are unlikely to cause your boiler to ‘explode,’ kettling is still a reason for alarm and in rarer cases, yes a boiler can explode. It is critical to act as quickly as possible to avert any potential long-term harm. 

Manufacturers are aware of these risks and have implemented safeguards to prevent future harm of the boiler but sometimes you can also turn the boiler off manually

Nonetheless, it is always better to seek the advice of an industry specialist to analyse the issue and give appropriate solutions for any boiler-related difficulties, including kettling.

Is it a good idea to turn a boiler off if it’s kettling?

Yes, It is a good idea to turn a boiler off if it is kettling. However, in rare cases if you have a kettling boiler but it is deemed safe it may not be necessary for safety purposes.

You will just have to deal with the inconvenience of having a noisy boiler until it is fixed.

What is the difference between a Combi and Conventional boiler?

Choosing the right boiler for your home necessitates taking into account a number of things. One of the most important considerations is the quantity of available space in your home. 

A combi boiler is your best option if you have limited storage space and cannot store a separate hot water tank. If, on the other hand, you’ve decided to go with a larger model of a traditional boiler, make sure you have adequate room to install the system. 

Another factor to consider is if you want to maintain the present system or upgrade to a new one. 

Depending on the boiler you intend to install, you may need to upgrade, and various systems demand varying amounts of room. 

As a result, you must decide if you are willing to spend the money on the upgrades.

A further crucial factor to consider is the availability of hot water as if numerous individuals in your family use hot water at the same time, you must consider the available space.

If you have limited room and several users, you’ll need a higher-output combi boiler but in contrast, if you have additional room and several users, you can go with a traditional boiler.

Another consideration is the quantity of bathrooms in your home as the greater the number of bathrooms, the greater the need for hot water, and the larger your boiler must be. 

A traditional boiler might be a better alternative if you have three or more bathrooms, as combi boilers can only deliver a single water flow and this means that if the flow is shared between numerous bathrooms, the water pressure will drop.

a broken boiler that is kettling

To conclude

It is fair to say that boiler kettling is something you don’t want to deal with as a landlord but it is important to be aware of it in case it does happen in the future. So, be sure to familiarise yourself with the signs if it does take place. More on this here.

On top of this, have a read of what you can do about boiler kettling to fix the issue before things get too severe as this could lead to putting people in danger and potentially ruining a property further.

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Donnell Bailey

Property expert

Donnell is a property expert focusing on the property market, he looks at a combination of legislation, information from property managers, letting agents and market trends to produce information to help landlords.


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