Five Bad Sounds Your Furnace Makes (And What They Mean)

Five Bad Sounds Your Furnace Makes (And What They Mean)

It’s not unusual for you to hear some sound coming from your furnace in the winter when you have it running. You may notice it turning off and on, but you also may notice a few different sounds coming from your heating system.


If you hear noises coming from your furnace, we want to tell you what they may mean, and what you should do about it. And, when it’s time to call your HVAC company about repairing your furnace.

Your Hear A Sound Coming From Your Furnace

If you hear a sound coming from your furnace, you should listen and assess the sound. It could be something you can take care of yourself, or it may be something more serious that you need to call an HVAC technician to take care of.


Here are five bad sounds you may hear coming from your furnace:

  1. Hissing or whistling
  2. Clanging and banging
  3. Rattling
  4. Popping
  5. Rumbling

Hissing Or Whistling

Hissing or whistling sounds coming from your furnace usually indicate air is escaping from the system somewhere. This could be due to a blockage in airflow, or maybe a leak in your duct. We recommend changing your air filter if it’s clogged. This could be causing air to build up if it can’t properly flow through the ducts.


If your system is still hissing after this, call a contractor. It could be a sign of a bigger problem, and you shouldn’t let it continue.

Clanging And Banging

If you hear clanging or banging sounds, it’s a sign of a problem. It’s normal to hear a little kick on and off at times with your furnace, but if you are hearing it banging, it could be a sign your system is having trouble lighting the burner.


Your burner has trouble igniting if it’s dirty, and then gas builds up. One it ignites, you hear that bang. This can eventually become dangerous, and harmful to your system.


You can avoid this problem by scheduling a regular service to have your system cleaned and tuned up!


A rattling sound is usually an indication of something being loose or broken. If your front panel is loose, it’s easy to tighten it up and the rattling should be gone. If you are hearing it coming from inside your furnace, it could be a sign of something more serious.


You could have a loose or broken component. If your heat exchanger is cracked, this could be a major issue, and one that is dangerous. If your heat exchanger is cracked, it could lead to carbon monoxide leaking into your home. This is poisonous, odorless gas that can even lead to death.


If you hear a rattling and it’s not coming from the front panel, you should call a contractor ASAP!


Popping sounds come from your ducts contracting and expanding when you have your heat on. This isn’t something you should worry too much about. If you hear it more often than usual, or coming from the actual furnace, then you should call in a professional. As long as the popping is coming from the ducts, and it isn’t breaking them, you should be just fine.

Furnace Noises and What They Mean - YouTube


It’s very normal to hear a low rumble when your system cycles off. If you hear a loud rumble, or it’s persistent, it could be a problem with your burner. Gas may be getting caught in the system and burning in the furnace, causing a rumbling sound. Again, we recommend calling an HVAC technician to take a look at your system and make sure everything is working properly.

Installing A Carbon Monoxide Detector

One of the most important pieces of equipment in your home is a carbon monoxide detector. In all these situations we described, aside from the ducts popping, there is a chance carbon monoxide leaks into your home. This is EXTREMELY dangerous, and a carbon monoxide detector will alert you if there’s a leak before it can cause you and your family any harm.


If your carbon monoxide detector goes off, turn off your heating system immediately and call your HVAC contractor!

HVAC Maintenance To Prevent A Broken Furnace

One of the best things we can recommend to prevent your furnace from making noise or breaking down is regular HVAC service. HVAC Maintenance will help your system last as long as it should, and run efficiently. If your system is dirty and unkempt, it’s likely that it will start using more energy than it should. This will cost you money in energy bills, cause more frequent breakdowns, and eventually lead to an early death of your furnace. Schedule service every year and get the most out of your furnace!