Tuckers Air Conditioning, Heating & Plumbing Blog

What You Should Know About Boiler Kettling

If your boiler is rumbling like a giant tea kettle, you may have a problem. Specifically, you probably have a kettling problem. Despite what it sounds like, your boiler probably isn’t going to explode. However, kettling can still inflict severe damage to both the boiler and the surrounding area. Let’s take a look at what causes kettling, how it can harm your system, and what you should do about it.


The main cause of kettling is hard water, which is water that has a higher than normal magnesium and calcium content. As hard water flows through your boiler’s heat exchanger, it deposits small amounts of these minerals on the walls of the pipe. These deposits eventually become lime scale; a white, chalky substance that is large enough to restrict the flow of water through the heat exchanger. This traps water in the heat exchanger for longer than it should, causing it to evaporate into steam.

Problems Caused by Kettling

Though it may seem counter intuitive, most boilers are not meant to actually boil water. When water in the boiler heat exchanger starts to evaporate, it puts enormous pressure on the pipe. The rumbling you hear is the heat exchanger struggling to cope with the steam inside it.

If the kettling is not dealt with as soon as possible, it becomes increasingly likely that your heat exchanger will rupture. If the pipe ruptures, it will cause enormous water damage not only to the system but to the surrounding area. If you want to avoid having to replace your heat exchanger, you should call for repairs as soon as you notice your boiler kettling.

If your boiler is kettling, call Tuckers Air Conditioning, Heating & Plumbing. We offer comprehensive boiler repair services throughout Gaithersburg, MD.