Reasons Why Your Furnace May Be Making Noises

It can be unnerving to start hearing weird noises coming from your basement when you’re sitting at home. What’s causing this racket? It could likely be your furnace. Furnaces have been a staple appliance in households for a long time, and just like any other appliance, they can act up and make noises at times. 

Several types of noises could be coming from your furnace, and there could be multiple reasons why. Below, we dive into why your furnace may be making certain sounds, what types of sounds it can produce and whether you should be concerned. 

Why Is My Furnace Making Noises?

Although this is can be an unconventional approach, the easiest way to determine why your furnace is making noise is by evaluating the sound itself. Some of the noises furnaces can potentially make include the following: 

Banging Sounds

Hearing a banging noise when you first turn on your furnace means it’s likely not lighting right away. When this occurs, gas builds up in the combustion chamber, and when your furnace finally lights, it can create a mini-explosion. 

Some main reasons for delayed ignition might include:

• A broken pilot light.
• Low gas supply.
• Dirty or misaligned burners.
• Too much air mixed with gas.

Shrieking Sounds

If you hear a high-pitched squeal or shrieking noise coming from your furnace, there is typically a problem with the blower. The blower within your furnace is powered by a motor containing bearings, and these components can eventually wear out due to age or overheating. Another cause of this noise could be a damaged belt. When discovered early enough, these issues can be an easy fix. But if you ignore this noise, these worn components can damage other parts of your furnace.

Scraping Sounds

A scraping noise from your furnace most likely results from a problem with the blower wheel. This noise will typically sound like metal rubbing on metal or nails scratching against a chalkboard. The wheel could be causing this noise for a few reasons. One reason is that the blower wheel is loose, causing it to scrape against the blower casing. The solution to this can be as simple as tightening the blower wheel.

Unfortunately, not all possible reasons for this noise are as simple as that. Two other potential causes include a broken blower blade and a broken motor mount, which causes the blower assembly to hit the housing. These issues will require help from an HVAC technician. If they remain ignored, they can severely damage your furnace.

Rattling Sounds

If you hear rattling sounds from your furnace, it can mean one of two things. Your furnace has a loose internal part, or the heat exchanger is cracked. 

Because furnaces are so complex, they require numerous moving parts. Because of this, parts can quickly become loose over time if they weren’t tightened enough. Various furnace parts can come loose and produce this sound, including these common components:

• Bearings in the blower motor.
• A worn blower motor fan belt, which mostly applies to older furnaces.
• Connections in the ductwork.
• Panels around the furnace.

As for the second potential cause, a cracked heat exchanger is a bit more serious. The heat exchanger is the portion of the furnace that creates heat, and it is filled with metal coils that heat up to warm the air. If there is a crack in the coils, this issue can cause the heat exchanger to rattle.

Whistling Sounds

If a whistling sound is coming from your furnace, it usually results from low airflow. Essentially, this means the blower cannot draw in enough air to heat. This malfunction can occur for a couple of reasons, such as:

• Dirty air filters.
• Blocked air vents.
• Unclean or damaged ducts.

Fixing this issue can be as simple as changing your air filter. If doing this doesn’t take the noise away, it is best to contact a trained HVAC technician to find the root of the problem.

Common Furnace Noises

Now that we have gone over all the possible reasons for why noises may be coming from your furnace, you may wonder when these noises are considered normal and when they shouldn’t be ignored. To help you identify them, here’s a list of normal sounds and other noises that you should pay extra attention to.

Normal Furnace Noises

Every appliance and machine emits regular sounds that occur from general operating, heating up and cooling down. If you hear these sounds from your furnace, you should not automatically be alarmed by them unless they come with other side effects:

• Chirp:A chirping sound is a typical furnace noise. Unless this turns into a screech or gets much louder, it is considered a standard sound that furnaces make.
• Rattle: If you hear subtle rattling noises when the system is cooling down, this is par for the course when operating a furnace and is typically nothing to be alarmed about.
• Hum:A hum will usually occur when the furnace is initially turning on, and it is generally followed by a clicking sound.
• Crackle: Once a furnace shuts down, crackling noises are common as the machine’s components cool down. 
• Ping/thumps: Pings and thumps throughout the house are also common noises you may hear from your furnace. While these sounds may seem alarming, they simply originate from the air ducts expanding and contracting.

Furnace Noises To Be Concerned About

In contrast, if you hear these furnace noises in your home, you should take immediate action to ensure nothing has gone wrong with your machine that could cause expensive damages:

• Banging 
• Whistling/shrieking
• Scraping 
• Exaggerated rattling

Contact a technician immediately before the problem does more damage to your furnace and bank account. Acting quickly will also save you plenty of headaches from sitting through these annoying noises. 

E.A.C. Heating & Air Can Solve Your Furnace Problems

Are you a business owner or homeowner in Hilton Head, Bluffton, Okatie or any surrounding areas? Are you regularly hearing noises coming from your furnace, need a heating repair or looking for regular maintenance? Contact E.A.C. Heating & Air today for help! 

As a company with over 30 years of experience and a designation as a Carrier Factory Authorized Dealer, we provide peace of mind through our quality service. Our highly trained professionals are more than happy to help you with your residential or business issues and find a solution to any HVAC problems you come across.