What Causes Boiler Kettling?

If you are experiencing boiler kettling, you might be wondering what’s causing the problem. Grove Heating & Cooling takes a look at some of the most common causes of boiler kettling and gives more details about the problems it can cause for your boiler heating system.

What Is Kettling?

Boiler kettling is a condition that can occur when certain issues impact a home’s boiler. Kettling can cause the boiler to shake, rattle and make loud noises that sound like rumbling, popping, boiling and even whistling. Many people think a boiler kettling noise is similar to the noise a tea kettle makes when it begins to boil, hence the name.

Boiler kettling can lead to serious damage to the heating unit and its components. Kettling may cause boiler pipes to burst, lead to steam emissions from the unit and even create dangerous electrical hazards in the home. In some cases, boiler kettling can even cause the boiler to explode.

If you hear boiler kettling sounds and think your boiler may be kettling, you should contact a qualified technician for service. This is a serious condition that should be fixed as soon as possible to avoid damage to your boiler.

Causes of Boiler Kettling

Now we’ll explain some of the common reasons behind a kettling boiler, which include mineral and sediment buildup, leaks, a faulty thermostat and boiler pump problems.

Mineral and Sediment Buildup

Kettling is most often caused by a buildup of scale or sediment in the boiler. This can happen over time as the boiler water evaporates and the minerals are left behind. When this happens, the boiler must work harder to heat the water, which causes it to boil. The boiler kettles when it is turned on because the water can’t flow through the sediment and scale. This buildup restricts water flow around the boiler’s heat exchanger, causing pressure to build up. When this occurs, the components can overheat, generate steam and produce the classic kettling noise.


Leaking boiler systems are another common cause of boiler kettling. When water leaks from the boiler system, it can cause a whistling noise. In addition, leaks can also result in a loss of pressure, which can also lead to boiler kettling.

Leaks can occur anywhere in the system, including piping connections near and to the boiler as well as the radiators and radiator pipes throughout your home. Leaks are most commonly the result of poor installation work, over-pressurization or corrosion in an older boiler.

Faulty Thermostat

Boiler kettling can be caused by a faulty thermostat. This is often an issue that impacts older boilers, as the thermostat can wear out over time and fail to communicate properly with the boiler.

When the boiler thermostat is not working correctly, the boiler can overheat and produce kettling sounds. In addition to kettling noise, another symptom you might notice is your boiler cuts out when you have the heat on. Boiler overheating can damage the boiler and cause it to leak, creating further problems and kettling. 

Malfunctioning Boiler Pump

Problems with the boiler pump can also result in boiler kettling. The boiler pump is responsible for circulating the boiler’s water and exchanging heat with the boiler’s heat exchanger. If the boiler pump fails, the boiler will not be able to circulate the water, causing the boiler to overheat and eventually shut down. In some cases, the boiler may also release steam, which can cause a loud kettling noise.

Professional Boiler Repair Services

Boiler kettling can result from a variety of problems with your boiler, so it’s important to get it fixed as soon as possible. If you are experiencing any of the symptoms of boiler kettling, please contact Grove Heating & Cooling for boiler repair in Maryland. We have the experience and expertise to get your boiler up and running again in no time.

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