When your furnace turns on for a heating cycle, does it make a loud BANG or BOOM sound? This can happen for a couple of different reasons, some of which are easy fixes and others that might indicate major safety issues with your system. Today we’re going to talk about why your furnace might make a banging sound when starting and what steps you should take to fix the problem!

Why does your furnace make a banging sound when starting?

There are two primary reasons why your furnace might make a banging sound when starting:

  1. Dirty furnace burners.
  2. Over time, dirt can build up on your furnace’s burners. This buildup gets more severe when your furnace filter is dirty and/or you skip annual tune-ups for your system. Regardless of the cause, dirt buildup on your burners will delay the ignition of the gas that is fed to your system. As a result, gas will build up inside of your furnace and when the ignition finally begins, it creates a miniature explosion inside of your system that makes a loud banging sound. This can be a serious safety issue with your system that can also lead to a cracked heat exchanger.

  3. Ducts are popping. Your ductwork expands and contracts during your furnace’s heating cycles. This can sometimes create booming or banging sounds when your air handler turns on and the pressure changes inside of your ducts. If this sound gets louder or occurs more frequently than usual, it’s likely due to pressure buildup in your ducts that is caused by a clogged air filter or closed vents in your rooms.

What should you do if your furnace is making a banging sound when starting?

Furnace noises should never be ignored, especially if they occur right when the system kicks on. If you hear a banging sound at the start of your heating cycles, contact Jerry Kelly Heating & Air Conditioning immediately so that we can send someone to your home to inspect the problem. You don’t want to take any chances if the sound is being caused by a delayed ignition.

How can you prevent your furnace from making a banging sound when starting?

  • Schedule annual furnace tune-ups so that we can clean your burners before every heating season.
  • Change your air filter every month to avoid pressure problems in your return ducts.
  • Keep all of your air vents open and clear of obstructions to avoid pressure problems in your ducts.

If you have any questions about why your furnace fan is always on, or if you’d like a heating system serviced or installed in your home, contact Jerry Kelly Heating & Air Conditioning, your St. Charles, MO, furnace installation and repair contractor. We service the St. Louis area, including towns like Weldon Spring, Wentzville, and Winghaven, MO.

photo credit: Q9F via photopin cc

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