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4 Causes Of Your Furnace Making Loud Noises

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A heating unit is an indispensable appliance during winter months. However, your system may malfunction with continued use or increased strain. When this happens, you may hear loud noises when the furnace operates, accompanied by a reduced performance. Since different issues cause various noises, you should know that it is best to engage a residential HVAC contractor instead of checking the unit yourself. This way, they will quickly diagnose your system, identify the cause of noise, and remedy it for seamless operation. The following are reasons you may experience loud noises from your unit.

Clicking Noises

If using a gas furnace, you may notice clicking noises when the ignition system is defective. This could result from dirt and debris building up around the burner, impeding the gas from lighting up. Additionally, a faulty valve may prevent the gas from reaching the system, causing the production of a weak flame. Finally, if the pilot light wears down, it may lead to an easily extinguishable flame. As such, you will hear clicking noises as your system attempts to ignite. Sometimes, your system will make clicking noises due to an object infiltrating the fan cabinet. 

Banging Noises

You should know that an ignition delay may lead to banging noises in the furnace. This could be due to leaky gas lines or dirty burners, hindering proper ignition. Moreover, gas may accumulate in the combustion chamber, creating a mini-explosion when it ignites. As a result, you will hear banging noises from the small gas explosion. On the other hand, your furnace may produce banging sounds due to the expansion and contraction of ducts. Note that this happens because ducts are subject to positive and negative pressure, causing them to make intermittent banging when expanding and contracting.

High-Pitched Squeal

A high-pitched squeal indicates a defective blower. This could result from the motor bearings deteriorating over time, especially due to overheating from dirt build-up. Consequently, you will hear whistling sounds as the fan attempts to rotate. In addition, your furnace will make a high-pitched squeal when the fan is straining to draw adequate air for heating. Note that limited air flow happens due to clogged air filters, obstructed return vents, or leaky ducts.


Your furnace may emit a relatively soft hum when it starts a heating cycle. However, if this sound escalates to loud noises, the system's electrical compartment could have malfunctioned. For instance, a power surge may cause the blower's capacitor to give out, preventing the motor from running. Alternatively, when your furnace transformer ages, it may not convert energy effectively. As a result, a defective transformer will make a humming noise as it fails to sustain the system at the correct voltage capacity.

A noisy furnace is an inconvenience in your home. Therefore, you should hire a residential HVAC repair service to check the source of the noise and repair or replace the problematic component. Also, ensure the expert services your unit as required to keep it in good working order.