HeatingDon’t Ignore These Furnace Noises


Is your furnace causing a ruckus? It can be concerning when your furnace is making scary sounds. When your furnace is working properly, it shouldn’t make too much noise. Although it’s not uncommon for your furnace to make a bit of noise when it starts up, some noises could indicate you should get your furnace looked at by a professional immediately. Below are some furnace noises you should never ignore.

Furnace noises you should never ignore

1. Banging
2. Rattling
3. Rumbling
4. Whistling
5. Squealing or Screeching
6. Clicking
7. Buzzing

1. Banging

inside of furnace

If you hear a loud bang when you turn on your furnace, we recommend you turn the system off immediately and contact us. You may have a gas buildup in the system, which is something you should never ignore. This issue could crack the heat exchanger, which is both unsafe and potentially costly.

2. Rattling

If your furnace is rattling, the issue can be as simple as a loose panel or loose screw. If it’s not either of these things, it could be from a leak or crack in your heat exchanger. A broken heat exchanger can leak carbon monoxide into your home, which is extremely dangerous.

Before attempting to work on your furnace, make sure you turn off the power. You can try tightening your panel or screws to see if that fixes the rattling sound. If this doesn’t solve the rattling noises, make sure you contact us ASAP.

3. Rumbling

A rumbling sound could simply mean your furnace needs some maintenance. You may have dirty gas burners or a pilot light that needs to be adjusted but note the color of your furnace flame. The flame should be blue, although a small yellow tip is fine. If your flame is any other color, contact your HVAC company right away. A flame that’s not blue could point to potentially dangerous conditions.

4. Whistling

hand replacing furnace air filter

If your furnace is whistling, it could be from a dirty air filter. If the airflow is restricted due to a clogged filter, it could cause your furnace to whistle. You can prevent this issue by making sure to keep your filters replaced. It’s a good idea to replace your filter every one to three months. Read more here to find out how to change the air filters in your home: How To Change Your Home’s Heating And Air Conditioning Filter.

5. Squealing or Screeching

Squealing or screeching normally means that something is wrong with your blower. The blower belt may be loose and off-track, or your motor bearings are failing and need professional attention. It’s good to get this looked at as soon as possible to avoid more expensive repairs down the road.

6. Clicking

It’s not unusual to hear clicking when you first turn your furnace on. This is simply your ignition clicking on. On the other hand, if you’re hearing clicking all the time, it usually signals a compressor or control panel issue. If your furnace in Bellevue, WA is constantly clicking, make sure to get it checked out.

7. Buzzing

furnace wiring

A buzzing noise normally means the issue is electrical. The issue could be from the transformer, blower motor, or capacitor. Specifically, buzzing could mean something is loose in your furnace’s transformer. Wear and tear over time can cause parts in your transformer to become loose and buzz, and the wires or the box may need to be tightened.


You don’t want to come home to relax after a cold day only to find your furnace is making annoying noises or not working properly. Make sure to pay attention to any furnace noises you hear since some of them could mean serious and dangerous issues. At MM Comfort Systems, we have the knowledge and experience to handle any furnace problem, including repairs or installation. We can ensure your home is not only warm but also safe. If your furnace is making noise or you just want to make sure your system is running smoothly, contact us.


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