It’s natural for your furnace to produce some noise. However, certain unusual sounds may indicate a problem with your unit.

By understanding common furnace noises and when to seek professional help, you can ensure your heating system operates efficiently and safely throughout the winter months.

5 Furnace Noises to Watch For

From whistling and rattling to squeaking and banging, your furnace can make a lot of weird noises. If you’re wondering why your furnace is so noisy, consider the following sounds and what might be their causes. If all else, call a local HVAC professional for furnace repairs.

   1. Whining

A few different problems could be causing your furnace to make a whining noise. It could indicate a damaged blower motor or blower belt. Or, the shaft bearings may need to be oiled.

Blower motor problems are usually caused by worn-out bearings or a worn-out blower belt. Over time, the lubricant in the bearings can dry out, causing friction and a high-pitched whining sound. If your furnace has a belt-driven motor, a worn or loose belt can also create the same noise.

Depending on the severity of the issue, an HVAC technician can easily repair or replace your blower motor and belt, or oil the shaft bearings.

   2. Whistling

Problems in your ductwork could be causing an eerie whistling sound coming from your furnace. This is relatively common in older furnaces and should be repaired to prevent further damage.

Common ductwork problems that cause whistling sounds may include:

• Air Leaks: Holes or gaps in your ductwork can cause air to escape, creating a whistling sound.
• Restricted Airflow: If too many vents in your home are closed or your ducts are clogged with debris, it can increase air pressure, leading to whistling.
• Loose Ductwork: Vibrating or loose ductwork may produce a whistling sound.

If notice any whistling noises, reach out to a certified technician for air duct sealing and repairs.

   3. Banging or Clanging

If you hear a loud banging or booming noise when your furnace starts, it could be caused by expanding and contracting air ducts. If there is too much static pressure in your furnace’s ductwork, it can expand and make a loud banging noise. There can be several causes of high static pressure, including undersized ducts, closed supply vents, or dirty air filters.

Banging noises in your ductwork can also be caused by oil canning. Oil canning means there is a weak spot in the ducts that requires more support. You can fix this issue by screwing a thicker piece of metal onto the weak spot.

You may also have an issue with piping if you hear a banging or clanging noise. The pipes sometimes contract as they cool down. Or, a banging noise could indicate dirty burners or a defective gas valve.

To determine the exact cause of why your furnace is making a banging noise, it’s best to call a heating professional.

   4. Rattling

A rattling noise from your furnace could indicate several issues. This may include:

• Metal Parts Cooling Down: If you hear a rattling sound when your furnace turns off, it is most likely caused by the metal parts cooling down inside the furnace.
• Loose Components: Check for loose panels, ducts, or blower components that may lead to rattling or shaking.
• Heat Exchanger Issues: In severe cases, a rattling sound could indicate a cracked heat exchanger, which is a serious safety concern.

While loose components may seem like a DIY task to fix, it’s always best to contact an HVAC professional just in case something else is causing the rattling noise.

   5. Popping

Popping noises from the furnace could indicate delayed ignition, dirty burners, or ductwork expansion. If there is a delay in ignition, a small gas explosion can occur, causing a distinct pop or bang. Accumulated dirt on the burners can lead to delayed ignition as well, creating popping sounds.

As mentioned above, expanding ductwork can also create popping noises. As the furnace heats up, the ducts will expand and contract, sometimes making distinct popping noises.

What To Do If Your Furnace Is Making Noise

If your furnace is making noise, first investigate to see if you can find the cause. Some issues, like replacing an air filter, can be easily resolved on your own.

However, most of the time, unusual noise from your furnace should be handled by a professional. While some homeowners may want to attempt DIY fixes, it’s best to let a professional handle the job. This is for the safety and comfort of you and your family.

It’s time to contact an HVAC professional if you notice any of the following signs:

• Loud, persistent noises
• Noises accompanied by reduced heating performance
• Unusual smells, such as gas or burning odors
• Signs of carbon monoxide poisoning
• Sudden increases in your heating bill

Remember: Never attempt to repair your furnace yourself. Improper repairs can be dangerous, and performing repairs yourself may even void any warranties on your furnace.

Instead, turn to the experts at GAC Services for help. Our HVAC professionals are here to assist you with your furnace needs. If your furnace is making noise, contact us today for repairs.