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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. If not treated, the entire boiler could break down. Let’s take a look at what causes kettling, and why it’s so dangerous.

The Cause of Kettling

Kettling is caused by a buildup of pressure in the boiler’s heat exchanger. The heat exchanger is the part of the boiler that heats the water as it flows through the system. The pressure buildup tends to be caused by hard water generating lime scale 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 (for the most part). The system is only supposed to heat water to a certain temperature below boiling before distributing it throughout the house. If the water gets trapped in the heat exchanger for long enough, it will begin to boil and evaporate into steam. Water expands several thousand times over when it evaporates into steam, which exponentially increases the amount of pressure on the heat exchanger. This rapid increase in pressure is what causes that 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. It might also be a good idea to have a water treatment system installed, in order to prevent the problem from recurring.

Magnolia Plumbing, Heating & Cooling offers comprehensive boiler repair services throughout Bethesda, MD.

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