Why is My Furnace & Ductwork Making Noise?

Every house makes it own noises, and you get used to them over time. The plumbing, furnace, dishwasher, clothes washer and dryer all operate with familiar sounds that you’re accustomed to. Most of the time, you won’t even notice these noises.

Occasionally, unusual popping or banging noises may come from behind walls or ceilings or from the furnace unit, and these can be unsettling. What’s a “normal” noise and what noises should you look out for? We’ll try to explain the sources of some of the duct and furnace noise that’s common in homes.

What Causes Duct & Furnace Noise?

Your home’s ducts deliver heated or cooled air from the furnace, heat pump, or A/C to every room in your home. A blower fan pushes this air through at a high pressure. As a result, it can sometimes force the ducts’ thin metal outward. When this happens, a banging noise can result.

Recent Ductwork Cleaning

Surprisingly, this is more likely to happen after you’ve had ductwork cleaned. With accumulated dust and debris removed from the ducts, the airflow can move unimpeded at higher speed and pressure.

Duct Shape

The shape of the ducts also can have an effect. Square or rectangular ducts are more prone to expansion than rounded or oval ductwork.

Whistling While It’s Working

A whistling sound emitted from supply registers is a good sign; it just means the air is flowing.

These duct or furnace noises are generally nothing to worry about. In fact, these noises can actually indicate that your HVAC system is working as intended.

Noises That Should Get Your Attention

If you start hearing loud banging sounds or popping noises from your combustion furnace, this could be more serious.

When the burners begin rusting or otherwise deteriorating, blockages can result. These blockages delay the flow of gas into the combustion chamber. When the gas finally does come out and ignite, a small explosion may occur.

Left unattended, the situation will only get worse. Talk with a professional technician about any noises you’re unsure of and they can help inspect and remedy any issues.

Consult the Pros

For more information on duct and furnace noises in your home, please contact us at 318-795-8000. We’ve provided quality HVAC and plumbing services to Shreveport, Bossier City and Natchitoches since 1960.