Why is My Furnace Making Noise?

why furnace make noise

Why is My Furnace Making Noise?

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Furnaces, while essential for maintaining comfort during the colder months, can sometimes become noisy, causing concern for homeowners. While some noises are normal and expected, others may signal serious issues that need immediate attention. This comprehensive guide will help you understand the common sounds your furnace might make, their potential causes, and when to seek professional help.


Normal Furnace Noises

Furnace Services in North Vancouver

It’s usual for your furnace to make low sounds while it’s operational. Typically, when you start your furnace, it produces some noises when the heating cycle starts. It can also make a pop or click as it fires up, followed by a dull hum. All these noises are normal and should not worry you.

As furnaces age, wear and tear increase, and they tend to be a bit louder. Newer furnaces, however, come with insulation and additional features that limit noise. Loud, unusual noises could indicate loose components or other serious HVAC issues.


Common Furnace Noises and Their Causes



Faulty Blower Motor

A high-pitched squeal or whistling sound often indicates issues with the blower motor. You might also experience rattling and loud screeching noises. The blower motor pushes warm air through the ducts into your home. Over time, the motor’s bearings can overheat or wear out, leading to loud noises. Reduced airflow, caused by damaged or dirty air ducts, closed air vents, or dirty air filters, can also strain the blower, creating a whistling sound. Rattling noises may occur if the motor mount is broken.


Dirty Burners

Loud bangs can indicate dirty burners. When burners are dirty, ignition is delayed, leading to gas buildup in the combustion chamber and causing a bang or small explosion upon ignition. Annual cleanings and inspections can help prevent these issues. Delayed ignition can also result from a broken pilot light, too much air mixed with gas, or a low gas supply. While the expansion and contraction of metal air ducts can also cause boom sounds, these are usually harmless.


Faulty Heat Exchanger

The heat exchanger prevents gas and combustion fumes from escaping. If you hear rattling noises, it might indicate a loose component or panel in the furnace. Persistent rattling could suggest a crack or leak in the heat exchanger, a serious issue that can lead to carbon monoxide leakage. Dirty coils, filters, or blowers can restrict airflow, causing heat to build up and crack the heat exchanger.


Loose Components

Increased wear and tear can cause furnace components to become loose, resulting in rattling noises. Loose panels or ductwork connections might also make noise. Proper installation by qualified technicians and annual tune-ups can prevent loose components and ensure optimal operation.


Faulty Ignition

A clicking sound often signals a faulty ignition system struggling to light. Issues such as a broken sensor, faulty pilot light, defective ignition board, or valve can prevent gas from reaching the system. It’s essential to have a technician inspect and fix ignition problems to restore furnace efficiency.


Loose Fan Belt

Some furnaces have a belt-driven motor that can become loose, producing screeching or squealing noises. Lack of lubrication in the shaft bearings and other moving parts can also cause squealing. A qualified HVAC technician can lubricate the moving parts and adjust or replace the belt as needed.


Faulty Blower Wheel

A loose blower wheel can make a loud clanking sound as it hits the blower house casing. If you hear such noises, turn off your furnace and contact an HVAC technician for an inspection. Depending on the extent of the damage, the blower wheel may need fixing or replacement.


Electrical Problems

A buzzing or humming noise might indicate an electrical issue. Common problems include a faulty transformer, aging blower motor, bad inducer motor, or a failing blower motor capacitor. Professional inspection is necessary to pinpoint and fix the electrical components.



What Should I Do If I Hear These Noises?

As mentioned, in some cases, furnace noises can be normal. But many of these noises can result in serious safety issues, such as carbon monoxide leaks, or broken parts that prevent your equipment from heating your home properly. So if your heating equipment is making any noise in excess, or you just aren’t sure what the noise means, it’s best to contact a licensed, experienced HVAC technician, like Total Line, to diagnose and repair the problem. For more information about Furnace Services in North Vancouver.


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For more information about specific services, check out Total Line’s pages on Tankless Water Heater Services, Furnace Services, and Heat Pump Repair Services in North Vancouver.

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