If your HVAC system is making strange noises—rattling, banging, popping—you’re not alone. Noisy ductwork is a common issue for homes with central heating and cooling. While it might seem like a minor annoyance, these sounds often point to underlying problems with your system.

So why do HVAC ducts make noise? Let’s break it down.

Common Causes of Noisy Ducts

1. Air Pressure Build-Up

One of the most common reasons for banging or popping noises is the expansion and contraction of metal ductwork due to air pressure.

When your HVAC system turns on, it pushes a high volume of air into the ducts. The sudden pressure increase can cause the metal to flex, creating popping or booming sounds. Once the system shuts off and pressure drops, the ducts contract again, often creating another round of noise.

2. Dirty Air Filters

Clogged air filters restrict airflow and force your system to work harder than necessary. This imbalance can lead to pressure fluctuations inside your ducts, causing whistling, rattling, or buzzing sounds.

Tip: Replace your filters every 1–2 months, especially during peak heating or cooling seasons.

3. Closed or Blocked Vents

Too many closed vents or dampers can trap air in your ducts and raise internal pressure. If you’re hearing booming or hissing sounds, it could be from the air struggling to escape.

Leaving multiple vents closed can also strain your HVAC system over time, reducing its efficiency and lifespan.

4. Bent or Collapsed Flexible Ducts

Poor installation or accidental damage can cause flexible ducts to kink or collapse. This restricts airflow and creates static pressure, which not only produces noise but also reduces performance.

A professional inspection can determine if your ductwork needs to be reconfigured or repaired.

5. Pests in the Ducts

Hearing scratching or rustling sounds in your vents? Rodents or small animals may have found a way into your ductwork. Aside from being unpleasant, this can pose serious health and safety risks.

If you suspect pests, call a professional immediately to assess and remove them safely.

Here are a few solutions that may help reduce or eliminate noise in your ductwork:

• Adjust the Fan Speed

If the blower fan is set too high, it may be pushing air too forcefully through your ducts. A technician can help calibrate your system to a more appropriate setting.

• Install a Bypass Duct

In multi-zone HVAC systems, bypass ducts help relieve excess pressure. This can minimize noise caused by too much air being forced through limited pathways.

• Upgrade to Larger Ducts

Sometimes the ducts are simply too small for the size of your HVAC system. Upgrading to a larger duct size can improve airflow and reduce pressure-related noise.

• Consider Different Duct Shapes

Round ducts tend to be quieter and more efficient than rectangular ones. If you’re planning a full replacement or renovation, switching to round ducts may be worth considering.

When to Call a Professional

While some minor issues (like replacing a filter) can be handled on your own, most ductwork problems require expert help. An HVAC technician can accurately diagnose the cause of the noise and recommend the most effective solution, saving you time, money, and stress.

Say Goodbye to Noisy Ducts with Kova Heating & Cooling

Noisy ducts aren’t just annoying—they’re often signs your HVAC system needs attention. Whether it’s a simple airflow fix or a full ductwork repair, our team at Kova Heating & Cooling is here to help.

We offer expert ductwork inspections, repairs, and system upgrades to restore peace and comfort to your home. From central air to ducted heat pumps, we work on all types of systems.

📞 Call us today at (360) 823-3111 to schedule a service or inspection, and get your home quiet and comfortable again.