Furnace Noises: What Could They Mean?

Posted on: 20 December 2016


With the cold season underway, now would be a good time to give your furnace a closer look. An inspection by a qualified contractor can help minimize the possibility of fuel inefficiency, malfunctions and insufficient heating in the dead of winter, ensuring your home stays comfy and your energy bills remain reasonable.

A visual inspection is always great, but sometimes, you don't need a closer look to know there is a problem. Strange, unsettling noises from your furnace often point to an underlying issue that needs to be fixed. Here are common furnace noises and what they could mean.

Popping noises

If you hear loud banging and popping in your furnace when it is turned on after long periods of nonuse, you could be having dirty furnace burners that need to be cleaned before the unit can run smoothly. Dust and other debris in the burners usually delay the ignition process and cause an excess buildup of gas, resulting in the popping noise.

Once the burners finally light, they usually produce a loud, banging noise. The banging in your furnace could also result from the expansion and contraction of your ductwork, which essentially means that they are undersized and need to be replaced so that enough hot air is circulated in your home.

Scraping and squealing noises

Scraping sounds from your furnace are never pleasant. The main culprit for the racket is often a loose or broken blower wheel that needs immediate fixing before it causes the entire blower assembly to collapse.

High-pitched squeals from your unit could also indicate a problem with the blower. These noises are often produced when you have a frayed/loose blower belt, poorly lubricated bearings or a defective blower motor.

In most cases, problems with the blower are caused by crushed, blocked, or undersized air ducts that obstruct the flow of air and cause the furnace to work harder. An HVAC contractor form a company like Doctor Fix-It can come in and perform the necessary maintenance to the blower assembly and remove obstructions in the air ducts to get your furnace back to working order.

Booming noises

If you hear sounds that resemble what you'd get from banging a metal trashcan with a metal rod, you are likely dealing with air duct issues. The booming noise often occurs if the air ducts are undersized, and air pressure causes them to flex outward when the furnace is turned on. 

Alternatively, thin low gauge metal may have been used to cut corners when the ductwork was installed. In both cases, a technician will have to come in and replace the ducts so that the noises stop.