Some sounds, like a quiet whirring or an occasional clicking, are perfectly normal to hear coming from your boiler.
However, if you’re hearing loud, intrusive sounds from your boiler, it usually means there’s a problem that should be addressed ASAP.
In this blog, we’ll help you troubleshoot the following loud boiler sounds:
Scroll to the section that best describes the sound you’re hearing for more information about what causes the sound and how to fix the problem.
Noise #1: A vibrating sound
Does your boiler sound like it’s vibrating?
If so, it’s most likely because of the following problems:
- Loose components
- The speed of the circulating pump is too fast
Sometimes components inside the boiler or panels outside the unit become loose, which causes the boiler to shake and make a vibrating sound while it’s operating.
Solution: Make sure all compartments on the boiler are shut and tighten any loose screws.
If the vibrating noise persists, you’ll need to contact a professional for assistance. A professional can tighten any loose brackets that secure the unit and check for loose parts inside the boiler.
The speed of the circulating pump is too fast
Boilers have a component called a circulating pump that moves water from the boiler to the radiators.
Standard circulator pumps run at a few, fixed speeds. If the speed on the circulating pump is set too high, it can produce a vibrating sound while the boiler is running.
Solution: Look for the circulator pump speed controls on your boiler and set the speed to a lower setting. If the humming sound persists, contact a professional for assistance.
Note: Some newer boilers have a variable-speed circulator pump that automatically adjusts its speed based on the heating demand called for by the thermostat. Since these pumps adjust themselves automatically, they should always be operating at the “correct” speed, so the boiler shouldn’t produce a vibrating sound while running. To know if your boiler has a variable-speed circulator pump, search your boiler’s model number online to find the manufacturer specs.
Noise #2: A banging sound
Do you hear a loud banging sound when the`` boiler first turns on?
If so, the culprit is most likely delayed ignition.
We’ll explain: If the burners in your gas boiler don’t ignite when they’re supposed to, gas can build up in your boiler. When the burners finally ignite, the gas buildup creates a mini explosion that results in a loud bang.
The following problems cause delayed ignition:
- Dirty burners
- An uneven mixture of gas and air
- A pilot light issue (only applicable to older boilers)
Solution: If your boiler is experiencing a delayed ignition, you’ll want a professional to fix the problem ASAP. Besides obvious safety concerns, the explosion caused by delayed ignition can also damage your boiler, so you’ll want to fix the problem sooner than later.
Noise #3: A popping sound
A popping noise from your boiler is most likely caused by kettling.
Kettling occurs when the heat exchanger (the part that heats water) overheats. When the heat exchanger gets too hot, the water produces steam bubbles. When the steam bubbles eventually move to a colder area, they produce a popping sound.
Several boiler issues can lead to kettling including:
- Mineral buildup on the heat exchanger (caused by hard water)
- Low water pressure
- The boiler water temperature is set to high
- The boiler thermostat is broken
Solution: First, try turning down the temperature on the boiler thermostat. If the thermostat is unresponsive or the popping sound persists, contact a professional to diagnose and repair the problem.
Noise #4: A gurgling sound
If you hear a gurgling sound coming from your boiler, it usually means that air is trapped in your boiler or radiators.
Air can enter your boiler system via faulty valves, leaks in the system or after routine maintenance. Besides the gurgling sound, trapped air also prevents your radiators from heating properly, so you may also notice cooler room temperatures.
Solution: To get rid of the gurgling sound, you can “bleed” your radiators, which simply means opening them up to let out air.
To bleed your radiators, follow these steps:
- Turn off your boiler (you don’t want to touch a hot radiator)
- Insert a radiator key into the valve at the top of the radiator
- Turn the key counterclockwise and let out air, using a small bucket to catch any spillage
- Continue turning the key until you stop hearing a hissing noise (this is the sound of air escaping)
- Once the hissing stops, retighten the valve
After you complete these steps, you can turn your boiler back on. If the hissing sound persists, contact a professional for assistance. The professional may need to drain your entire system or search for other issues that could be causing the gurgling noise.