A Noisy Furnace: Reasons and Solutions

Posted: 2022-01-20

No one wants to deal with an extremely noisy furnace. Not only is it irritating, but it can also mean you’re about to spend money on repair. To help you determine why your furnace acts weird, keep reading.

Four Seasons Air Specialists is your trusted heating company in White Bear Lake MN. We help homeowners keep their furnaces quiet and their homes comfortably safe. Here are some reasons a furnace produces excessively loud sounds.

A Malfunctioning Blower Motor

Loud screeching and rattling noises coming from your furnace can mean the bearings in the blower motor or the blower motor itself are malfunctioning. Your blower motor drives the warm air out of your furnace and through the air ducts in your home. The blower motor requires routine lubrication, and often a specific kind of lubricant to maintain its optimum performance. Otherwise, the fan might seize up and cause a loud noise—not to mention a deafening repair bill.

If you have the knowledge or training, you can add lubrication to the motor. But be warned that this is not an easy DIY project. It requires careful motor removal. That’s why it’s best to call a professional technician for a proper inspection, lubrication, and any other necessary repairs or maintenance to eliminate the loud sound.

Loose Bolts, a Cracked Motor Fan Belt

Another common reason for your furnace to produce a rattling sound is a loose bolt in the access hatch. The hatch was probably opened and closed recently, but the bolts were not screwed down tightly. Using a wrench, you can easily fix this yourself. But for your safety, be sure to turn the furnace off before doing so.

A rattling sound can also be caused by a cracked blower motor fan belt. Such belts are similar to the ones in car engines, connecting the motor to the fan. If the belt suffers any damage, it can make a rattling noise as it works. If this is the case, the belt will need to be replaced before it becomes loose and causes more damage. This step requires the expertise of a qualified technician.

Filthy Burners, Air-to-Fuel Ratio Issues, Expanding Ducts

Heads up: do not ignore your furnace burners. If your furnace has dirty burners, you could be hearing a loud bang or boom when you turn the system on. Dirty burners can be a problem because they can delay the ignition. A delayed ignition causes gas to build up and could start a fire or cause an “explosion."
Therefore, you should consider annual inspections and cleanings to keep this issue under control. During a professional tune-up, all furnace burners are inspected and cleaned, eliminating safety risks.

An unbalanced air-to-fuel ratio can also produce a loud reverberating sound. To enable your furnace to work properly and efficiently, it needs a proper mixture of air and gas. If you have too much air and insufficient gas, gas can build up and result in a loud thundering sound.

Whether you have dirty burners or an unbalanced air-to-fuel ratio, you will need a professional to come and inspect the entire system to provide the proper cleaning and perform the necessary adjustments.

A booming sound could also mean that the metal air ducts are expanding and contracting as the temperature changes. This scenario is natural, and does not indicate any damage to the unit. But if the issue becomes quite alarming, there are some solutions you could discuss with your preferred HVAC company, including duct sealing and insulation, duct replacement, and air filter management.

A Dirty Filter, Defective Gas Supply Valve

Your furnace filter may be a part that is fairly easy to maintain but neglecting it can cause several problems, one of which is a whistling sound. This sound happens when the heated air struggles to pass the space left by the dirty filter. The dirt contributes to the motor’s wear and tear since it works harder to blow air through the small openings left on your filters.

Another reason why your furnace produces a whistling sound is a defective gas supply valve, which causes the gas flowing through your system to come out at high pressure. If you smell gas in your home, it’s best to turn the furnace off and call an HVAC professional to protect your home from fire and the effects of inhaling the gas.

Need Help? Call Four Seasons Air Specialists

To get rid of these loud sounds and restore the peace in your home, give us a call. As your friendly Dellwood HVAC repair company, we’d love to help you get the job done in no time.