The Most Common Noisy Boiler Causes & How To Fix Them

November 10, 2021

Your boiler should quietly do its job of providing steam or hot water for your heating system. A noisy boiler can be annoying and unnerving, so it’s important to act quickly when you hear these noises before it escalates into a more serious problem.

What Makes A Hot Water Boiler Noisy When Heating Water?

If your boiler is suddenly making strange noises, it could be a sign of a larger issue that needs to be taken care of. Here are some common noises that may require some maintenance work to fix:

  • Banging noises
  • Bubbling noises
  • Gurgling noises
  • Tapping noises
  • Vibrating noises
  • Whistling noises

If you’re hearing additional noises not listed above, reach out to Lozier Heating & Cooling for more assistance diagnosing your noisy boiler causes.

Lime Scale Buildup Inside Your Hot Water Boiler

Limescale is a white, chalky substance that can build up on appliances that use water. Limescale buildup occurs most often on hot water appliances in areas that use hard water. This buildup can cause long-term problems in your boiler that limit the efficiency of the heating system, because the limescale restricts the flow of hot water to your heating outlets. This can ultimately lead to higher utility bills because the boiler will need to work harder to maintain its desired temperature.

Limescale build-up on a hot water boiler.

Source: Great Radiators

What are the symptoms of lime scale buildup?

If you suspect limescale buildup in your boiler, there are a few key noises to listen for. Bubbling, popping, and gurgling noises, also known as kettling, are caused when the water reaches a boiling point within the boiler and then interacts with the colder water in the higher portion of the boiler. Limescale buildup can cause kettling due to the restricted water flow creating hotspots in the boiler that cause water to reach its boiling point more quickly

What are the causes of lime scale buildup?

Limescale is caused by a buildup of calcium and magnesium minerals that form calcium carbonate when hard water evaporates. Because hot water evaporates faster than cold water, limescale often builds up quicker on hot water appliances. If you live in an area with soft water, you won’t have to worry about limescale buildup, because soft water doesn’t contain these minerals.

How do you fix lime scale buildup?

Unless your limescale buildup damage is from overheating, or the calcification is too significant, it can typically be removed by a professional through a process called descaling. A certified HVAC service professional at Lozier can treat your boiler with chemicals to break down the mineral deposits and remove them.

Excessively High Water Temperature

Most boilers are programmed to maintain a certain temperature, but when boiler parts or safety features fail, the temperature can rise to dangerous levels. Luckily, most modern-day boilers are equipped with a lockout system to automatically shut off the boiler if temperatures rise beyond normal levels. Excessively high water temperatures can damage components in your boiler or lessen the heating efficiency of your system, ultimately resulting in higher utility bills if not treated appropriately.

What are the symptoms of excessively high water temperature?

Loud bubbling or boiling noises are a common symptom of high water temperature. If these noises prolong and your boiler does not automatically shut off when temperatures rise, this can quickly become dangerous.

What are the causes of excessively high water temperature?

There can be many reasons for high water temperature in your boiler, but here are the two most common causes:

Faulty Thermostat

If your thermostat malfunctions, that can cause the system to overheat and boil loudly. In this case, a certified professional will likely be able to replace the thermostat to fix your overheating boiler.

Foreign Contaminants

Overheating and boiling can be caused by contaminants in the water. These contaminants can cause foaming that limits the appropriate, efficient operation of the boiler and its tubing, resulting in overheating.

How do you fix excessively high water temperature?

If you hear bubbling noises you think are resulting from high water temperature, you should first try lowering the thermostat temperature for a short-term solution. This will likely help until a professional can take a look for a true fix, but should not be used as a long-term solution because it will impact water temperatures and heat output.

If lowering the thermostat doesn’t help, the next thing to do would be to call a professional to have them determine if the problem is caused by contaminants or another issue with the system.

Air Leaks & Trapped Air

Faulty pipes or connections can lead to air leaks or air getting trapped in the system. Addressing these issues quickly can help you avoid inefficient boiler operation, which can lower your heating efficiency and cause more damage to your heating system.

What are the symptoms of air leaks & trapped air?

If you hear hissing or whistling noises coming from your boiler, pipes, or radiator, you may have an air leak. If you have trapped air in your boiler, here are some signs to look for:

  • No hot water from taps or showers
  • Hot water sputtering from taps
  • Cold spots on one or more radiators

What are the causes of air leaks & trapped air?

The most common causes of air leaks in your boiler include corrosion, faulty water pipe connections, a damaged valve or pump, or a broken seal. If you have malfunctioning valves on your expansion tank or damage to pipes or connections, that can let unintended air into the system to become trapped.

How do you fix air leaks & trapped air?

Fixing a leaky boiler involves bleeding the valves to let out excess air. If you have a radiator bleed-key or a screwdriver, you can attempt to bleed your boiler valves on your own to let the excess air out, or you can contact a professional for assistance. If bleeding the valves doesn’t work, you may have damaged connections or pipes that will need to be repaired by a certified HVAC professional.

Inadequate Water Supply

When water pressure is low or the tank’s water supply is inadequate, the heat in your boiler dissipates too slowly, causing boiling or kettling. Low water supply can cause damage such as loosened or cracked tubes, melted metal, or leaking water. In rare cases, low water supply can be dangerous and potentially cause an explosion due to intense pressure buildup. However, most modern-day boilers have a low water cutoff system in place to prevent this from happening.

What are the symptoms of inadequate water supply?

Boiling, gurgling, or kettling noises are one way to determine if you might have low water supply. If you hear those noises, check the gauge glass on your boiler to check on the water levels visually. If you don’t have gauge or sight glass on your boiler, look for other gauges or dials on your system to determine water levels.

What are the causes of inadequate water supply?

Inadequate water supply can be caused by many different factors, but is typically caused by faulty valves, frozen pipes, incorrectly sized pipes, or incorrect flow-rate settings.

How do you fix inadequate water supply?

A certified professional can fix inadequate water supply issues by repairing or adjusting any damaged pipes or valves, by replacing improperly sized piping with ones that can supply enough flow and pressure, or by fixing the flow rate settings of your system to the appropriate levels.

Is Your Noisy Combination Boiler & Hot Water Heater Still Keeping You Up At Night? Call A Lozier Certified HVAC Technician!

For more information about noisy boiler repair or maintenance, contact Lozier Heating & Cooling today! Our technicians have experience with all types of boilers, including treating limescale buildup and fixing faulty boiler parts.

Need immediate assistance? Call our 24-hour emergency service number at (515) 267-1000 or text us at (515) 393-4262 and someone in our office will get an appointment scheduled for you.