Furnace noises can be unsettling. From clattering, banging and popping in the ductwork to clicking and squealing in the furnace itself, furnace noises can range from those that are typical, to those that indicate trouble. You don’t want to pay for service that is not necessary if the noise is normal. However, you want to be diligent about correcting possible malfunctions in a timely manner, to ensure they don’t become more costly. It is important to understand what noises from your HVAC system could mean to ensure that you do not ignore something that is potentially very serious.

Types of Noises

Noises can emanate from ducts and from the furnace. Generally, duct noises can be easily explained. Although there are different types of noises that can come from ducts, it is beneficial if you can distinguish what they are, and what they possibly mean.

Duct Noises

If banging or popping sounds can be heard in the ductwork after the system comes on, it’s most likely the sheet metal sides expanding to accommodate the air pressure that’s flowing through the ductwork is made of thin sheet metal, which tends to expand and contract with changes in air pressure. Sometimes having ductwork cleaned can cause popping, banging and other noises associated with expansion. When ductwork is clean, debris and dirt that may have been slowing down the airflow are removed, and the air pressure increases, causing the metal to expand. While this is harmless, it may be startling or annoying. Ductwork that hasn’t been cleaned may also emit banging, clanging or popping sounds. In this case, debris and obstructions may be causing a problem with airflow, resulting in noises. Getting a professional duct cleaning will help. Other ways your HVAC technician can mitigate duct noises:

  • Replace square rectangular ductwork with round or square ducts. Round is best, as it allows the air to flow most freely through the ducts.
  • Improve the ductwork design to allow for fewer bends and turns. The fewer obstacles in the ductwork, the better air can flow.
  • Replace thin residential-grade sheet metal ducts with commercial-grade sheet metal, which is much thicker. It won’t expand and contract as much.
  • Adjust the actuator inside the duct dampers to diminish banging.
  • Add insulation around ductwork.
  • Check dampers on the supply side of the ducts to see if they are open or closed. If several are closed, this could cause the banging.
  • Have the fan inside the ductwork cleaned.

Sometimes noise in the ducts can be caused by small animals. They sometimes make their way out, but at other times they can become trapped. It is best to contact pest control in case a scared animal attacks. This is especially worrisome if they are carriers of diseases such as rabies. In addition, waste and shedding from animals can end up in your indoor air, affecting air quality and aggravating respiratory problems. If the animals die within the duct system, the foul odor can end up affecting the air quality throughout your entire home.

Furnace Noises

Furnaces too, will make various noises, with several possible causes. Furnace noises are generally more concerning because they can be signs of something potentially dangerous. Furnace noises are often common when you first turn on the system after months of no use. Typical furnace noises include:

  • Booms and bangs may also arise from delayed ignition. Burners get clogged or dirty over time. When there is a call for an increase of temperature, a clogged or rusty burner may delay ignition.
  • Loud scraping can signal a malfunction with the furnace’s blower wheel. It may be loose and need tightening, or it could be broken and need replacing. Another possible cause of a loud scraping noise could be a broken motor mount.
  • High-pitched squealing might be caused by a loose or frayed blower belt, shaft bearings requiring lubrication or a blower motor malfunction.
  • If you hear a rattling noise, the cover panels might need to be tightened. If it persists, it may be that the blower is out of alignment or the motor is malfunctioning.
  • Clicking sounds are only normal when the furnace turns on and off. If you hear repeated clicking coming from the control panel, a relay may be broken and in need of repair.
  • Grinding noises could be a sign that the bearings are worn out and need replacing.

It is best to consult a technician as soon as possible for any new sounds from your HVAC system. A sound that you might think is harmless could be a sign of a real or developing problem. It is far better to be wrong and there is nothing wrong with the system, than to ignore sounds that need to be addressed right away.

System Noises Could Be Costing You

If the sounds from your system are an indication of a problem, it is quite likely that your system is not performing as efficiently as it should. Noises could also result from loose or damaged parts. If that is the case, your HVAC system might be working harder to keep your house at the temperature set at the thermostat.

The increased effort by the system could lead to further wear. You are likely to see an increase in your energy bill also. If the furnace is working harder, it is consuming more energy.

There is also a safety concern. Furnace noises could be a sign of electrical problems that could lead to a fire. Damage to the furnace could also result in carbon monoxide leaks that could lead to illness and even death.

Maintenance Is Key

Routine maintenance is one of the best ways to ensure your system is free from the kind of damage that would lead to these noises. During routine maintenance, your technician checks the entire HVAC system — the indoor as well as outdoor components. Your technician will thoroughly check and clean the system. Routine maintenance not only keeps your system performing as it should, but will also mean you are less likely to be faced with the dangers such as fires and gas leaks.

Furnace maintenance is recommended once a year, during fall. This will ensure that your furnace is in a better condition to handle whatever winter might bring. Maintenance works because it saves you from untimely system breakdown and helps to extend the life of your system.

If your system is old or needs a lot of repair, it is time to consider an upgrade . Don’t sacrifice comfort and safety, ensure that your furnace is in the right condition to meet the needs of your household.

If you are concerned about furnace noises, other HVAC-related sounds, or if there is anything about your system that does not seem to be quite right, contact Roberts Heating & Air Conditioning right away. We have been serving the Northbrook area since 1979, and our qualified technicians can provide the services and systems you need to improve system performance and comfort in your home. Call us today at 847-272-5836 for more information or to schedule an appointment.

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