You Could be Eligible for Up to $2k in Tax Credits! Learn More Today! Read More

Skip navigation


AW Heating & Cooling Blog

Heater Sounds You Shouldn’t Ignore


When it comes to the holiday season, there are some common things you’ll hear—perhaps carolers traveling through your neighborhood, holiday music on your radio, toy and gift ads on the TV. What you shouldn’t be hearing, however, are strange and unfamiliar noises coming from your heating system.

Now, no heating system is silent. You’re going to hear it cycle on and off. If you have a ducted system, you’ll hear the ducts making a bit of noise as they expand and contract with the temperature fluctuations going through them. You’ll also, of course, hear the whoosh of air as the heat blows through your vents.

But you shouldn’t expect to hear much else beyond this. If you notice sounds you’ve never heard before or loud noises that just don’t seem normal, it’s likely time to give us a call. Keep reading as we delve into what types of sounds we’re referring to.

A Loud Bang or Boom During Startup

We’ll start with the sound that often scares homeowners the most—a loud banging or booming noise coming from your furnace. This is especially concerning if it’s a gas-powered system. If you hear it happening consistently rather than just when the furnace starts up, then you may have a problem with the air ducts or sheet metal siding of the furnace expanding and contracting—due to either poor installation or improper heating system sizing.

But if it’s only happening at startup, then you have a reason to be concerned. The noise can be something as relatively simple as a dirty furnace burner. But that dirt enables gas to buildup, causing a short of mini-explosion when they do ignite. This may not affect your home right away, but it rattles the heat exchanger, which can eventually crack and leak dangerous carbon monoxide gas into your home.

A Squealing Noise

Any squealing noise you hear from your furnace might be the result of a lack of lubrication or a blower fan belt that’s wearing down. This means it’s an easy fix for our technicians, but it doesn’t mean it’s not a big deal. If you let this go on for too long, the fan can stop working altogether, disallowing the furnace from operating when you need it the most.

It’s better to have your system repaired at the first sign of a problem than wait on it and end up with an even bigger, more expensive repair, or even premature replacement.

Low Rumbling

This can certainly seem like a pretty concerning sound. We can’t say with absolute certainty what the cause is, without seeing and hearing your furnace or heater for ourselves. However, one common explanation is that the pilot flame is too low.

Check the flame of your furnace to confirm that it’s blue instead of yellow or orange. Otherwise, that rumbling noise can be attributed to a dangerous carbon monoxide leak, depending on the unit. So shut off the system and call for help if you believe this to be the case.


Finally, let’s talk about scraping—we’re talking about a metal-on-metal noise. This should never be ignored when it’s happening in your furnace. What you’re most likely hearing is the motor mount coming loose form its casing. In other words, the metal-on-metal sound you’re hearing is indeed metal-on-metal.

This may not seem like a big deal, but the damage that can result due to this will lead to replacement if it’s not handled right away.

For expert heater repair in Toledo, OH, contact “Your Comfort Specialists” here at AW Heating & Cooling today!

Comments are closed.