Kettling boiler (attached to tankless water heater) in basement of Washington DC home.

Why Boiler Kettling is Dangerous

Is your boiler making a deep rumbling sound as though it were a giant tea kettle about to boil over? That sound is, appropriately, referred to as kettling, and it’s a symptom of a pretty serious problem with the system. 

When your boiler sounds like a tea kettle, you need to take fast action to remedy the problem; otherwise, the entire system could break down. Let’s take a look at what causes kettling in a boiler and why it’s so dangerous.

What Causes Kettling in a Boiler

Kettling is caused by a buildup of pressure in the boiler’s heat exchanger. This alone should give you a hint as to why a kettling boiler is dangerous and needs to be addressed immediately. 

The heat exchanger is the part of the boiler that heats water as it flows through the system. The pressure buildup tends to be caused by hard water generating a buildup of limescale inside the heat exchanger, which restricts the flow of water through the system. As the flow of water is restricted, the water becomes trapped in the heat exchanger for longer periods of time. This is where the problem starts. 

Believe it or not, boilers are not supposed to actually boil water—otherwise, boiler kettling would be normal for the most part. The system is supposed to heat water up to a certain temperature below boiling before distributing it throughout the house. However, hot water that gets trapped in the heat exchanger for long enough will begin to boil and evaporate into steam. 

Water expands several thousand times over when it turns into steam, which exponentially increases the amount of pressure on the heat exchanger. This rapid increase in pressure is what causes that boiler rumbling sound you’re hearing as the heat exchanger struggles to contain the steam being produced. 

The best way to treat this is to have the heat exchanger scrubbed out. Of course, this should only be performed by a professional. In fact, anytime your boiler is making noise, it’s a good idea to get on the phone with a technician. 

Now that you know what causes kettling in a boiler, it’s important to understand why a kettling boiler is dangerous.

Is Boiler Kettling Dangerous? 

Yes and no. 

Theoretically, enough pressure buildup inside the boiler can lead to burst pipes, steam emissions, and electrical hazards. The worst-case scenario would be the boiler itself exploding. 

Luckily, most modern boilers have built-in safety features that detect rising pressure levels and shut off the unit before a catastrophe happens. If your boiler is new or has been well-maintained over the years, you can rest easy knowing that your family and home are safe from any worse-case scenarios.

Keep an ear out for banging noises, vibrating noises, rumbling noises, or boiling water sounds coming from a boiler that is over 10 years old or has not seen a professional technician since the day it was installed. Safety mechanisms can suffer from wear and tear or may not even exist in older systems.

Steps to Prevent Boiler Kettling

Why deal with another heating repair bill when you can prevent boiler kettling in the first place? Is it even possible to avoid the cause of kettling in a boiler? 

Yes, and there are two ways to make sure your boiler is in good working order and never becomes a danger to your home.

Prevent Boiler Kettling With These Tips

Boiler Kettling Sounds Keeping You Up at Night? Call Magnolia

You know what causes kettling in a boiler and why boiler kettling is dangerous. With that said, if your boiler is making a vibrating, rumbling, or banging noise, it’s time to take action.

Magnolia Plumbing, Heating & Cooling offers comprehensive electric and gas central heating boiler repair services throughout Washington, D.C. Call today to schedule a service.