Why is my furnace making strange noises?

Like people, when furnaces get old they start making strange noises. Some noises are natural, but others could be a sign of a serious problem.

Please don’t ignore any of these furnace noises. They’re signs of problems that need to be fixed, not ignored.

Leaving them alone will lead to an expensive repair that could have been avoided.

Banging noise

Possible causes: This scary noise has 2 possible causes: dirty burners or an air duct issue.

You’ll know if the burners are dirty if your thermostat is saying your home needs heat and the furnace delays turning on. You see, when the thermostat calls for heat, gas is sent to the burners. But if the burners are dirty, they have a hard time igniting the gas. So the gas builds up.

Guess what happens when it finally ignites the gas? BOOM! There’s the noise.

You’ll know if it’s an issue with the air ducts if…well, you hear it coming from the ducts near the furnace. The noise is the ducts expanding and contracting because of:

  • Undersized ducts
  • Too many dampers closed
  • Clogged air filter

The proper fix: If the burners are dirty, have a professional clean them. If the ducts are popping out, try opening dampers or changing the air filter. If the noise continues. Contact a professional for help.

Grinding noise

Possible cause: This metal-rubbing-metal noise is probably caused by an issue with the furnace’s squirrel cage blower wheel. Stop reading this article and turn off your furnace to prevent damage to your furnace.

The proper fix: The fix depends on the specific issue:

  • If the wheel is loose, a professional needs to tighten it.
  • If the wheel is broken, it needs replacing.
  • If the the motor mount is broken, it needs repairing.

So many noises, so little time

These are just a couple common noises a furnace can make. Didn’t see the noise your furnace is making covered in this article?

Feel free to ask one of our experts to help you troubleshoot your furnace or give us a call at (913) 856-5801 and we’ll come diagnose your problem.

Santa Fe Air Conditioning and Heating serves the Kansas City area.