You're used to your furnace running as quietly as it's designed to be. When you hear unexpected noises coming from your furnace, it's naturally a cause for alarm. Loud and unusual noises can be caused by any number of issues. Some of these issues are relatively minor and easily solvable, while others signal the need for a licensed HVAC expert to step in.

The following gives you an idea of what sounds to keep your ears tuned for. You'll also learn some of the underlying causes and how you can get your furnace back to its relatively quiet self.

Rattling Noises

Rattling noises often stem from loose components. These components include panels that were incorrectly reinstalled or improperly tightened after a previous service. Some fasteners can also back themselves out due to excessive vibration.

Here are a few things that can be done to nip those rattling noises in the bud:

• Locate and tighten loose fasteners.
• Make sure every panel is properly installed.
• Check for loose ductwork and reinforce with duct tape or additional screws.
• Place rubber or cork pads underneath the furnace to reduce vibration and noise.

Whistling Noises

Whistling noises usually indicate a problem with airflow. The ducts may be too small for the amount of air your furnace pushes, for instance. Gaps and tears in the ducts can also cause air to whistle past. Even your furnace air filter can create whistling noises if it becomes extremely clogged with debris.

Like before, here are a few ways to eliminate those whistling noises:

• Check and replace the furnace air filter on a regular basis.
• Check the ductwork for any signs of damage or improper installation.
• Consider upsizing your furnace's ductwork to match its airflow needs.

Squeaking Noises

Furnaces also rely on proper lubrication to function quietly. A lack of lubrication or use of the wrong lubricant can cause some moving parts on a typical furnace to make noise. Keeping up with regularly scheduled maintenance is key to eliminating noises typically caused by incorrect or inconsistent lubrication.

On furnaces that rely on belt-driven motors, a worn-out rubber drive belt can also squeak and squeal. Poorly fitted metal ductwork and metal panning used to create panned joists for return ductwork can also make noise during furnace operation.

Squeaking noises that eventually devolve into metallic scraping sounds may be the result of a failed blower motor bearing. Replacing one of these components requires the expertise of a trained heating furnace repair professional.