Is Your Boiler Making Noise? Common Causes and Fixes

HVAC Logo IconBy Tom MoorNovember 9, 2023

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HVAC technician servicing boiler

Is your boiler making noise while it operates? If so, you’re not alone. Boiler noise can be a cause for concern, but fear not – many issues are easily fixable once you identify the source. In this guide, we’ll explore common boiler noises, their potential causes, and practical fixes to bring peace back to your heating system.

Common Causes of Boiler Noises

Boiler noises, while often indicative of underlying issues, may not always pose an immediate safety concern. However, certain sounds, such as loud banging or rumbling, could signify potential problems like pressure irregularities or sediment buildup that, if left unaddressed, may compromise the boiler’s efficiency and safety. If in doubt or if the noises are accompanied by other concerning signs, consulting a professional technician is the best course of action to maintain a secure home environment.

Boiler Kettling

One of the most notorious boiler noises is a loud, rumbling noise reminiscent of a boiling kettle. It may also sound like a boiler whistling, or your boiler making a banging noise.

This phenomenon, known as “boiler kettling,” occurs when there’s a buildup of limescale or sludge in the system. This restricts water flow through the heat exchanger, causing it to overheat and steam, which results in the familiar kettle-like rumbling noise. Regular maintenance, including flushing the boiler to remove sediment, can prevent this issue and keep your boiler operating smoothly.

Boiler Making Banging Noise

If you hear your boiler making a banging noise, it might also be due to a phenomenon called “water hammer.” Water hammer occurs when water suddenly changes direction, causing pipes to vibrate and make loud banging noises. You may notice these boiler noises if your pipes aren’t pitched correctly or they are uninsulated, an incorrectly sized water line, or a boiler pressure setting that is too high. Check and adjust the pressure setting according to the manufacturer’s recommendations, and call your boiler professional to inspect your pipes and water line for issues.

If your boiler makes a loud noise on ignition, this banging can signal various underlying issues that demand immediate attention from a professional. One common culprit is delayed ignition, where the ignition sequence takes longer than usual, causing an accumulation of gas before ignition occurs. This delayed combustion can result in a sudden and forceful ignition, leading to an audible bang. Additionally, issues such as a dirty or malfunctioning burner, gas valve problems, or ignition electrode issues can contribute to the disruptive noise.

Boiler Sounds Like Running Water

If you hear a gurgling, running water sound from your boiler, it may indicate air is trapped in the pipes, disrupting the flow of water. To remedy this, try bleeding the radiators to release trapped air. To bleed your radiators, follow these steps:

  1. Turn Off the Heating System: Ensure the radiator is cool before starting.
  2. Gather Tools: Get a radiator key or screwdriver, a container, and a cloth.
  3. Bleed Valve: Locate the bleed valve and place a container below it to catch water. Open the bleed valve, using the key or screwdriver. Listen for hissing as air escapes, and wait for steady water to flow from the valve.
  4. Close Valve: Turn the key or screwdriver to close the valve once water flows consistently.
  5. Check Pressure and Repeat: Confirm the boiler’s pressure, repressurize if needed, and repeat the process for each radiator, starting from the lowest floor.

If the gurgling persists, or you’re not comfortable tinkering with your boiler, consult a technician to investigate potential issues within the system.

Boiler Making Buzzing Noise

A vibrating or buzzing boiler can be attributed to issues with water pressure, a faulty circulator pump, loose components, a malfunctioning gas valve, or electrical issues. These sounds are often indicators of impending problems that should be addressed promptly. If the boiler’s water pressure is not in the recommended range, you can adjust the water pressure according to the manufacturer’s recommendations. If the issue persists, consult a professional to inspect the system for other issues and make the necessary repairs.


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