Troubleshooting Noisy Furnace Ducts

Maintenancing noisy  furnace ducts

“Did you hear that?”

“What was that sound?”

“Was that the furnace?”

How often do you ask those questions in your home? Living with furnace ductwork can mean living with all sorts of sounds, some benign, some signs of that it’s time for to call a heating service professional.

That’s why we’re focusing this week’s blog on some common ductwork issues, and troubleshooting noisy furnace ducts just by listening.

1. When your ducts are snapping…

These sounds are the most common sounds you’ll hear from your ducts, and probably nothing to worry about. Snapping and popping noises are the sound of your ducts expanding and flexing as a result of changing air pressure and temperature as your system turns on.

Sealing heating ductwork2. When your ducts are rattling…

While this sound can be unnerving, it’s typically the sign that your furnace ductwork is loose or sized incorrectly. When your HVAC system is working, loose ducts will rattle against each other.

It’s not a matter of life or death, but it is costing you money, as loose ductwork can lead to the loss of heat, and thus a higher energy bill.

3. When your ducts are whistling…

The idea of “whistling while you work” might have been OK for Snow White. When your furnace whistles as it works, it’s probably due to constricted air flow.

Check the filter in your furnace to see if it’s time for a replacement. From there, look at your vents to make sure they’re open and clear of debris. It’s not a serious issue, but it could lead to more significant problems. Have your HVAC professional look at it during scheduled maintenance.

iStock-490908462_RT.jpg4. When your ducts are vibrating or humming…

This noise usually means the air flow return section of your heating system is clogged, leading to a massive drop in air pressure. The smaller the blockage, the longer the vibration/humming noise will last. Near-total blockages announce themselves with a short, loud, sudden hum.

5. When your ducts are scratching and buzzing…

This ductwork problem has nothing to do with your furnace. Instead, you’ve likely got mice, insects or other pests living within the ducts to escape wintry weather.

6. When you hear squealing noises…

You might be tempted to squeal yourself. The fan or motor belt in your furnace is frayed and ready to give, leading to a persistent, loud squealing noise. It needs to be replaced, and soon.

7. When you hear a booming noise…

This could be a serious problem. Soft, infrequent booms are common, a sign that the furnace plenum – an air distribution box – is expanding.

But a loud, frequent booming noise is the sound of delayed furnace ignition, which can threaten your entire HVAC system. Consult with an expert right away.

maintenancing a furnaceIf your furnace ductwork is making noises you aren’t sure about, All Seasons Comfort Control can help.

We offer preventative maintenance agreements to our residential customers. We’ll check your ductwork as part of a larger HVAC system inspection and make sure your heating system is at its best for years to come. If you don’t have a maintenance agreement, we can still help. 

We recommend having your system checked at least once a year. Contact us today to learn more about our pre-winter heating maintenance plan.