The 7 furnace noises: Your troubleshooting guide from JNJ

It’s natural for your furnace to make some sound while in operation. However, how do you know when your furnace noises are normal, and when something is wrong? From whistling to pops, there are 7 furnace noises you need to listen for this winter.

If you’re hearing them, it might be time to call a HVAC professional for a heating repair inspection.

JNJ is a professional heating and cooling business serving Elgin, South Elgin, and other communities along the Fox River in Illinois. For heating maintenance or other services, contact our team.

The 7 furnace noises (and what they mean)

Not all furnace noises are the same. Different parts make different sounds within the machine. In fact, being able to identify the sound being made can help a professional HVAC technician know where to start inspecting a system.

With that in mind, here are the big seven furnace noises and what they mean for your system:

1. Whistling

This is one of the most common issues an older furnace might have. It might “whistle” if it has a dirty air filter or has a high-density filter that stops proper airflow. That’s because air is being forced through a small space, causing that high-pitched sound.

2. Squealing

If the blower shaft or electric motor has bearings that have seen better days and gone without heating maintenance, you might hear squealing or whining noises from the furnace. If you don’t get those bearings looked at or fixed, that squealing sound will turn into a grinding noise eventually. At that point, it might be too late to repair the system.

We recommend having the furnace checked out at the first squeal. It’s true what they say: the squeaky wheel does get the grease.

3. Flapping

If your furnace is old and you hear a flapping noise, one of two things might be wrong with it. The fan belt might have worn away, or it might have gotten too loose to remain in place. A tapping or squealing noise might also be the result of the same issues. In any case, you should get the furnace checked out quickly before incurring more damage.

4. Squeaking

A furnace that seems fine on the outside is not necessarily working fine. For example, if you hear a squeaking noise coming from an apparently perfect-looking furnace, the blower unit might be askew. You might also hear a rattling noise if the unit is not mounted correctly. This is a problem with installation: you need to call JNJ for service.

5. Rumbling

The blower wheel acts like a vacuum: without a proper covering or with a defective filter, it can suck in foreign objects. So if you hear a rumbling noise coming from it, chances are the fans sucked up paper or solid dirt into the unit. This can happen if the filter is not replaced or cleaned regularly. Hire professionals to replace the filter and you will hear the last of that rumbling.

6. Popping

If you hear a pop when your turn on the furnace, it can be because the furnace is too dirty. The dirt can slow down the ignition process, resulting in gas buildup. So when the accumulated gas catches fire, it will be followed by a pop or a loud bang.

If this noise is ignored, you might need to have the heat exchanger replaced, which will not be cheap. Regular maintenance can prevent this issue and save you from the costs as well.

7. Banging

There are two main types of banging sounds that come from the furnace. The first, described above, is when a dirty ignitor allows gas to be built up, which then is ignited in a miniature explosion. This, obviously, requires the immediate attention of an HVAC professional.

However, another more common banging sound is the sounds your home’s air ducts make as the heat running through them causes the metal to expand and contract. In a vast majority of cases, this is harmless and normal for your ducts.

Our tip: Listen to where banging sounds are coming from. Are they coming from other parts of your home (duct expansion) or just from your furnace (furnace ignitor)? Are they consistent (furnace ignitor) or just occasional (duct expansion)? When in doubt, give the pros at JNJ a call for an inspection. Here’s a video guide to furnace knocking issues.

Hire the professionals at JNJ Heating & Air Conditioning to inspect your furnace

When you’re hearing strange furnace noises, it pays to better safe-than-sorry. A professional HVAC technician can inspect your system and give you peace of mind this winter. To get in contact with a trusted HVAC company right here in Elgin and South Elgin, contact JNJ.

We offer 24/7 emergency furnace repair!

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