Why are my HVAC ducts making a popping sound?

Why are my HVAC ducts making a popping sound?

Is your air conditioner making noises at night? Getting a good night’s rest is impossible if you hear loud popping, cracking, and banging from your HVAC -- it’s even worse if you’re trying to sleep after watching a horror movie! Whether loud ductwork puts you on edge or not, nobody wants to hear noises in their home.

All HVACs make a slight humming sound when they’re on, but when the noise becomes excessive, it can indicate a bigger problem. The first thought that comes to mind is that your HVAC needs extensive repairs. Fortunately, the reason why ducts “pop” is often not a cause to worry.

How often are your ducts popping?

If you hear only occasional popping, it’s most likely no big deal. Your HVAC might just be expanding due to temperature. HVAC ducts are made of thin metal, so when warm air gets inside, this causes the metal to expand slightly. If the noise sounds like someone is knocking on a thin sheet of metal, it’s generally harmless.

However, if your ducts make a noise almost every day, this might signal a more serious issue. When this happens, it’s best to call an HVAC technician.

Why are your ducts making a popping sound?

Ice inside the unit

Popping noises are caused by ice inside the unit. This happens when your HVAC system isn’t draining or if the temperature is always set low. A properly functioning HVAC system should be able to detect when ice forms inside the unit and then thaw automatically. When this happens, try bumping the temperature up.

Water inside the unit

After heavy rainstorms, water can enter your AC unit, causing serious damage as well as popping, cracking, and banging noises. Turn off the power and inspect the outdoor unit for debris that might be trapping water inside. The bad news is that if the water is inside the unit, it’s already damaging sensitive components.

Noisy duct shape

Air ducts come in three shapes: square, rectangular, and round. The quietest are the round ducts while the loudest are rectangular ducts. The differences in noise occur because each duct shape can handle different pressure thresholds. Round ducts can handle the greatest amount of pressure. The easiest (but expensive) solution would be to replace your ducts, but it’s best to consult an HVAC specialist for more affordable solutions.

Furnace issues

Sometimes, newly installed furnaces can create popping noises. This is because your furnace may not be compatible with your HVAC system. When old equipment is installed on a new system, or when new equipment is added to an old system, your HVAC unit simply won’t function as intended. Vibrations from the furnace’s blower can result in rattling noises.

Time for HVAC maintenance

In most cases, your HVAC might just need servicing to get rid of the noise. HVAC maintenance is an overlooked part of regular home maintenance, primarily because of its cost, but is an extremely essential step in making your unit last longer and run more efficiently. Maintaining your HVAC also improves indoor air quality, allowing you to sleep and breathe easier.