Duct & Furnace Noises Can Cause Concern, But Not All Mean Trouble

Posted on: November 17, 2015

It can be unsettling to wake up to strange pops and whistles on cold nights in your North Carolina home, but it’s not an uncommon occurrence in forced air HVAC systems. Duct and furnace noise may occur at any time, particularly right after a professional duct cleaning.

The good news is that it’s rarely a sign of ductwork damage or other problems, but the duct and furnace noise can be intrusive. If you think that you need help right away, you can contact Air Experts in Raleigh, NC now! Otherwise, read on to learn the most common types of noises and what you can do about them.

Common Ductwork Sounds & How to Diagnose Them

Though most duct sounds are perfectly normal and generally not too concerning, they can be a nuisance. It can help to know why the sound is happening, and if there’s anything you can do to alleviate it! Luckily each sound is somewhat unique in its cause, making diagnosis for even a laymen quite easy. It’s just about knowing what you’re hearing and why you’re hearing it:

  • Popping and snapping. Pop and snap sounds are some of the least harmful, and most common. You hear this one when the ducts are flexing—most frequently when the system is first kicking on, since the sudden change in air pressure and temperature cause some natural expansion. Typically you’ve nothing to worry about here, but if the sound drives you bonkers you might look to replacing your ducts with something a bit more soundless.
  • Whistling sounds. Whistling comes as a result of constricted air flow, and the issue could be happening for one of a few reasons. You should check your furnace filter to see if it needs to be replaced, then move on to vents to ensure they’re all open and free of debris. This sound isn’t too dangerous in and of itself, but it can lead to problems down the line, so be sure to either remedy the issue on your own, or call in for a furnace repair specialist.
  • Rattling. Rattle noises are sort of spooky, but they are most likely simply the result of loose or incorrectly sized ductwork. When the system is on and air pressure is optimized, loose ducts can rattle against each other and cause this obnoxious and long-lived sound. The problem isn’t critical, but it does indicate that you’re losing heat, and thus probably paying a good bit extra in energy costs.
  • Vibrations and humming. The problem is nearly always a block or clog in the air flow return portion of your HVAC system, causing a sudden and large drop in air pressure. The vibrations can be consistent for smaller blockages or partial ones, or loud, sudden, and short-lived for nearly complete blockages.
  • Scratching, sampling, and buzzing noises. It’s unfortunate, and not at all pleasant, but you’ve probably got a pest problem. Mice, other vermin, and even bugs can take up residence in duct systems in the off season, making a home of the warm dark ducts.
  • Big or loud booming. If the sound is infrequent and sort of soft, then this is normal—it’s just the plenum on your furnace expanding, and is quite common. But fi the boom is loud and happening often, then we’re sad to say you’ve got a big problem. This is caused by a delayed furnace ignition, and can pose a considerable threat to your HVAC equipment, and even your home! Call an expert immediately.
  • Squealing sounds. Persistent squealing (usually very loud) will be a frayed or damaged fan or motor belt. This will need to be repaired or replaced quite soon, as it will eventually lead to a furnace breakdown.

Contact Air Experts for Furnace or Duct Services in Raleigh, NC Today!

For additional help or information about duct and furnace noises, contact Air Experts online today, or call us anytime at 919-480-2727! We provide comprehensive services for all your HVAC needs in Raleigh-Durham and surrounding areas.

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