Why Is My Furnace Making a Loud BOOM noise? A New Jersey Tech Answers | Air Experts

So every time your gas furnace kicks on you get the same pattern of noises:

Click…click…(short pause)…BOOM!

It’s a scary noise and, unfortunately, it’s just as scary of a problem. So what’s going on?

If your furnace makes a loud BOOM sound as it starts up, you have a problem called “delayed ignition”. Delayed ignition is caused when gas builds up inside your combustion chamber, leading to a small explosion when it finally ignites.

So, what’s causing this gas buildup? We’ll answer that. But first, it’ll help to take a look at how your furnace is supposed to ignite…

Normal gas furnace ignition vs. delayed ignition

When your gas furnace gets the call for heat, this is the basic breakdown of what should happen:

  • Step 1: The gas valve opens and delivers gas into the combustion chamber.
  • Step 2: The gas is ignited immediately by the furnace ignitor (or the pilot light if you have an old furnace).
  • Step 3: That ignition creates a steady flame that heats up your heat exchanger and warms the air that’s pushed into your home.

But during delayed ignition, there’s a breakdown somewhere between step 1 and 2. Instead of the gas immediately igniting, the gas just builds and builds, accumulating enough fuel and energy for a mini explosion once ignition finally occurs.

And that explosion can crack or damage your heat exchanger, allowing dangerous carbon monoxide to leak into your home.

What causes delayed ignition?

Several things can cause delayed ignition, including:

  • Pilot flame problems
  • Not enough gas coming from gas burners
  • Too much gas coming from gas burners
  • Dirty, rusty or clogged burner ports

Unfortunately, you’ll need a professional to determine which of these issues is your problem. They’ll be able to troubleshoot your system and then repair your furnace.

Need help from a New Jersey tech?

If you’re dealing with delayed ignition, don’t wait to fix it.

Over time, delayed ignition can worsen and lead to expensive furnace repairs or even system replacement.

To save yourself money (and protect yourself from gas leaking into your home), just schedule your appointment today and we’ll fix your furnace.

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