Some factors that cause excessively noisy ducts include dents or damage, loose metal parts, dirty or blocked vents, and closed dampers.
Insulate Your Ductwork
If your ductwork isn't properly insulated or doesn't have insulation, add insulation to duct runs in the basement or attic. The insulation should be formed and designed to insulate ducts. The insulating material will muffle loud noises from within and it can improve energy efficiency as well.
Thermal Expansion: As the furnace heats the air, the metal ducts expand. When the furnace turns off and the air cools, the metal contracts. This rapid change in temperature can cause the ducts to flex and make popping or banging noises.
If the noise is just air movement, you will want to line the duct with absorbing material, or create a baffle. If you go this route, do not use materials that can become airborne such as fiberglass. Closed cell foam would be the safest.
You should be accustomed to the sound of your HVAC system running. A low hum or the sound of blowing air is normal. If your air vents suddenly become very noisy and distracting, it's often a sign of a more serious issue. Depending on the problem, there may be an easy or more complicated fix requiring a professional.
Those sags and bends can make it harder for your system to move air, which can increase static pressure and create noise. Dirty air filters or ducts: Over time, the dust and dirt buildup on your air filters and inside of your ducts makes it hard for your equipment to move air. It can also make the system noisier.
Possibly the best, most professional and reliable ways to reduce noise from ventilation ducts & reduce the risk of cross talk is to use a specialist duct noise reducer. Called circular sound attenuators, or silencers, these will decrease the sound transmitted throughout your ventilation ductwork.
If you notice an AC vent rattling noise or clanking sound, it could mean that your metal duct joints are loose or disconnected. Use metal tape to reconnect the joints, then call a local AC repair pro for a long-term fix.
Rodents, bugs, and accumulated dirt are common culprits. Wind, air currents, and failing ductwork can also generate sounds that go bump in the night.
An HVAC duct silencer is specifically engineered to reduce airborne noise carried along ducts or produced by enclosures. You'll also find these silencers described as sound attenuators when they are used in industrial settings.
Experts advise having your air ducts cleaned every 2 to 3 years to prevent many maintenance and health problems before they start. However, homes with pets or children with allergies should have their air ducts professionally cleaned more frequently than the recommended average.
But if you notice a bad odor once you turn on the system, there might be a problem with your ductwork. Similarly, a lot of dust in your house indicates that your ductwork is damaged and dirty. Broken ductwork plays a major role in restricting clean air from flowing throughout your home.
HVAC air ducts are frequently comprised of metal which makes them prone to causing noise with even the most minor disturbances. This ductwork noise can be a source of frustration for homeowners when it's constant or excessively loud.
In most cases, noisy pipes are caused by movement as they expand and then knock against other surfaces. Therefore, one of the best ways to solve this problem is to check that all pipes are securely fastened and that they're not touching anything else.
Regularly replacing the air filters, as recommended by the manufacturer or HVAC technician, can significantly reduce fan noise, improve indoor air quality, and enhance overall system efficiency. You can also know your filter needs to be changed by looking at the color.
A whistling or roaring sound from a supply air vent could mean the vent has either too much air flowing through it or the volume damper inside the vent is partially closed restricting the normal airflow. Homeowners often close vents in empty rooms so they don't spend money to heat or cool unoccupied space.
Check the dampers on the supply side of your ductwork and try opening them up one at a time to see if this reduces the popping and banging noises. You can also adjust the actuator inside of the duct dampers up or down to reduce the duct noises. If you don't know how to do this, contact your local HVAC technician.
One of the most common causes of noises in the attic is wildlife. Animals such as bats, squirrels, raccoons, mice, and even birds can find their way into attics seeking shelter or food. Squirrels are particularly active during dawn and dusk. They make scratching sounds as they climb walls or scamper across floors.
Steps to soundproof ductwork include changing the structure of the ductwork, lining the interior with sound absorption, creating a soundproof barrier for the exterior, and adding baffles for soundproofing inside the air vents.
If the usual noise volume increases, or you start to hear flapping, rattling or high-pitched sounds from the supply vents, return grilles or ceiling diffusers, it's likely due to an increase in pressure caused by airflow restrictions somewhere in the HVAC system.
Animals like squirrels, raccoons, and rodents can find their way into your house and into the ductwork. They can even make a new home in the ducts, which becomes a serious problem for your home. If you think you hear scratching coming from your ductwork, it's incredibly important to call professionals right away.
Overtime, dirt and grime build up on the fan blades can cause the fan to become noisy. Make sure that the fan blades are clean. If the fan is worn out or damaged, it may begin to make noise as it spins. We recommend you to check for wear and tear of the fan.
Rattling Noise
Air vents can also make rattling noises when small items are inside them, such as nails or toys. This type of noise can also occur when you have a supply register that has come loose. In this case, tightening the register can stop this rattling sound.