Why is My Furnace Making Loud Noises?

Furnaces often make noises, particularly older models. Normal sounds included small pops from the ducts and the humming of the system as the blower runs.

However, if you notice noises that are very loud and disruptive, your furnace may need repairs, maintenance, or perhaps complete replacement. It is important to understand that ignoring these noises is a huge mistake because what’s causing them could result in more expensive repairs and replacement costs in the future.

The following are three types of noises that indicate serious issues with your heating system.

Loud Metallic Scraping Sound

A loud scraping noise which sounds like metal rubbing against metal often means there is a problem with the heater’s blower wheel. If you recognize this noise, shut off your furnace immediately and contact a licensed HVAC technician to inspect and repair the issue.

Common problems with the blower wheel include:

  1. The blower wheel is broken.
  2. The blower wheel became loose from the motor shaft, causing it to hit the blower casing.
  3. The mount to the motor broke, resulting in the entire blower assembly dropping and hitting your house repeatedly.

Squealing or Whining Sound

A high-pitched, squealing noise typically doesn’t indicate a serious issue. However, it is important to get noise fixed or else ignoring it can result in further problems later on.

Common causes of squealing or whining noises include:

  1. Loose, slipped, or frayed blower belt.
  2. Blower motor malfunction
  3. Shaft bearings that require oil

Loud Bang or Pop When the Heater Turns On

Dirt in the furnace burners impedes the burners from igniting, causing gas to build up. As soon as the gas finally ignites, you will hear a loud bang. These small explosions could crack the heat exchanger, which is a costly repair.

In addition, the loud banging sound may be coming from your air ducts, especially if you have metal ones. When the furnace blower turns on and off, the ducts expand and contract. This could mean that your ducts are undersized or flimsy, dirty air filter, or blockage in your vents.

If any of these strange noises are coming from your furnace, call for professional services right away.

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Contact 72 Degrees Air Conditioning & Heating and schedule an inspection and repairs from our licensed HVAC technician in Fredericksburg and Kerrville, TX.