Gas combi boilers are a popular choice for home heating and hot water systems, but they can sometimes produce noises that can be concerning for homeowners. Understanding the different types of noises and their causes can help you determine if your gas combi boiler is operating normally or if it requires attention.
Normal Sounds
Quiet Whirring Sound
This is the sound of the boiler’s circulation pump, which is responsible for circulating water around the boiler’s burner and heat exchanger, and potentially pumping hot water to the radiators. The pump typically operates at a speed of around 2,000 to 3,000 revolutions per minute (RPM), producing a quiet whirring sound.
Deep Rumbling Sound
The sound of the flames igniting and vigorously boiling the water passing over them can produce a deep, rumbling sound. This is a normal part of the boiler’s operation and is typically louder when the boiler is working at its maximum capacity.
Occasional Quiet Clicking
The boiler’s thermostats and control panel trigger various switches and valves inside the boiler, which can produce occasional quiet clicking sounds. This is a normal part of the boiler’s operation and is not a cause for concern.
Abnormal Noises
Gurgling Noises
Gurgling noises can be caused by trapped air in the system, which can be resolved by bleeding the radiators. If the issue persists, it might be due to a frozen condensation pipe, which can be thawed using hot water bottles. Gurgling noises can also be caused by a blockage in the boiler’s heat exchanger, which may require professional attention.
Grinding Noise
A grinding noise is typically caused by a faulty pump and requires immediate attention from a Gas Safe engineer to prevent overheating. The pump’s bearings may be worn, or the pump may be malfunctioning due to a buildup of debris or limescale.
Banging Noise
Banging noises can be caused by a faulty boiler thermostat, often due to limescale buildup in the heat exchanger. This can cause the thermostat to malfunction, leading to sudden changes in water temperature and pressure, which can result in banging noises.
Rattling Sounds
Rattling sounds can be caused by loose bolts in the boiler or blocked air in radiator pipes. Tightening loose bolts or bleeding radiators may resolve the issue. Rattling can also be caused by a worn-out pump or other internal components.
Humming or Constant Droning Noise
Humming or constant droning noises can be caused by issues with the central heating system, high boiler pressure, or a faulty boiler fan. The boiler’s pressure should be maintained within the recommended range, typically between 1 and 2 bar. If the pressure is too high, it can cause the boiler to produce a humming or droning noise.
Whining or Buzzing Noise
A whining or buzzing noise can indicate worn pump bearings and requires immediate professional attention. This type of noise can be a sign of a more serious issue that needs to be addressed promptly to prevent further damage to the boiler.
Whooshing Noises
Whooshing noises are often caused by a blocked circulation pump and require professional diagnosis and repair. This type of noise can be a sign of a more complex issue within the boiler’s internal components.
Prevention and Maintenance
Annual Servicing
Regular servicing by a qualified Gas Safe engineer can help identify and replace worn-out parts, preventing noise issues and ensuring the boiler’s safe and efficient operation. During the annual service, the engineer will inspect the boiler, clean the components, and check for any potential problems.
Proper Installation
Ensuring that the boiler is installed correctly can minimize the risk of noise problems. Improper installation can lead to issues such as air pockets, incorrect water flow, and other problems that can cause abnormal noises.
System Condition
Maintaining a well-conditioned central heating system can help prevent issues like kettling, which can cause noise. Regular flushing of the system and addressing any underlying problems, such as limescale buildup, can help keep the system running smoothly and quietly.
Technical Specifications
Boiler Pressure
High boiler pressure can cause humming or droning noises and may need to be adjusted. The boiler’s pressure should be maintained within the recommended range, typically between 1 and 2 bar.
Pump Speed
Adjusting the pump speed can help resolve issues like humming or constant droning noises. The pump’s speed can be adjusted by the boiler’s control panel or by replacing the pump with a variable-speed model.
Gas Supply
Ignition failure can cause clicking or tapping noises and may be related to the gas supply to the property. Ensuring that the gas supply is adequate and that the boiler is receiving the correct gas pressure can help prevent these types of noises.
DIY and Professional Intervention
Bleeding Radiators
Bleeding radiators can be a simple DIY step to resolve gurgling noises caused by trapped air in the system.
Tightening Loose Bolts
Tightening any loose bolts in the boiler can help resolve rattling sounds.
Professional Help
If you are unsure about the cause of the noise or if the issue persists after taking preliminary steps, it is recommended to call a Gas Safe engineer for assistance. They can diagnose the problem, identify the root cause, and provide the necessary repairs or maintenance to restore your boiler to quiet, efficient operation.
References:
– Ideal Heating. (n.d.). Why Is My Boiler Making a Noise? Retrieved from https://idealheating.com/tips-and-advice/why-is-my-boiler-making-a-noise
– BOXT. (2022, April 18). 9 Reasons Why Your Boiler Is Making a Noise. Retrieved from https://www.boxt.co.uk/boilers/guides/9-reasons-why-your-boiler-is-making-a-noise
– Reddit. (2023, January 6). Logic combi boiler making gurgling noises is it going to blow up? Retrieved from https://www.reddit.com/r/askaplumber/comments/1056b2z/logic_combi_boiler_making_gurgling_noises_is_it/
– MyBuilder. (2013, May 16). New Combi Boiler-now have humming noise all through the house (it’s worse at night when heating off). Retrieved from https://www.mybuilder.com/questions/v/11135/new-combi-boiler-now-have-humming-noise-all-through-the-house-it-s-worse-at-night-when-heating-off
– Heating Help. (2020, December 17). Combi boiler Noise? Retrieved from https://forum.heatinghelp.com/discussion/182135/combi-boiler-noise