5 Furnace Noises You Can't Afford To Ignore

Posted on: 4 September 2018

Imagine you're sitting on the couch enjoying the heating comfort your furnace has to offer. Suddenly, you hear a strange noise you've never heard from your furnace before. You could ignore the noise and hope the problem solves itself, but turning a deaf ear to your furnace could prove to be an expensive mistake.

Strange noises from your furnace could indicate a problem that's worth checking out. In most cases, you can even pinpoint the exact problem simply by recognizing the noises in question. If you need to troubleshoot a noisy furnace, this quick guide can help you identify those noises as well as their underlying causes.

1. Banging

In a typical gas furnace, ignition occurs as soon as you turn the furnace on. A delayed ignition can cause gas to build up within the furnace. When the furnace finally ignites, the gas buildup causes a larger-than-normal explosion—nothing to rival a Michael Bay movie, but enough to give anyone a scare. Dirty furnace burners or a faulty igniter can lead to ignition delays and subsequent gas buildup.

Your furnace ducts can also join in on the fun. Metal ducts that expand and contract due to temperature changes can also cause banging noises, although these noises aren't as dramatic as a delayed ignition. Nevertheless, you can solve this issue by properly sealing and insulating your ducts.

2. Scraping

If you hear plenty of scraping and scratching from your furnace, there's a good chance the blower fan is at fault. Metal blower fans can get knocked out of alignment and scrape against their metal housing. Blower fans can also suffer bearing damage, resulting in plenty of scraping and scratching. A poorly installed blower fan assembly can drop out of place, damaging the blower fan and its housing.

Needless to say, any scraping noises should be met with a cursory glance at your blower fan assembly. Check for any signs of damage. If there's any metal-on-metal contact between the fan and its housing, have your trusted HVAC technician make corrective repairs.  

3. Screeching

Those horrible screeching sounds could be the result of a loose or damaged blower fan belt. Check the belt tension and make sure it's not too tight or too loose. Look at the belt itself and watch for any cracks, glazing, dry rot, or other physical damage that suggests wear or defects.

On furnaces without a belt-driven blower fan, other moving parts can make screeching noises when they're not lubricated properly. It's up to your HVAC technician to inspect and, when necessary, lubricate these components to restore smooth, silent operation.

4. Rumbling

As it turns out, that rumbling noise isn't from your stomach—it's the result of a furnace with dirty gas burners or an improperly adjusted pilot light. Soot and debris buildup on the burners can block and distort airflow, creating a deep rumbling noise as the burners struggle to maintain a flame. A professional burner cleaning and pilot light adjustment can help ease the rumbling and even improve your furnace's overall efficiency.

A more dangerous source of rumbling in your furnace is the heat exchanger. Dangerous gases, including carbon monoxide, can escape through cracks in the heat exchanger, potentially creating a low-pitch rumble as the gases escape. A leaky heat exchanger must be checked and replaced as soon as possible to keep your home safe.

5. Rattling

Loose hardware such as a panel or fastener can also cause unpleasant rattling noises inside your furnace. Over time, vibrations from normal furnace operation can work panels and other components loose. In a few rare cases, sloppy installation or maintenance can result in loose or missing screws, which in turn leads to rattling panels and brackets.

Once you've pinpointed the exact source of the rattling, carefully tighten any loose fasteners you encounter. Loose screws and bolts can come into contact with other parts of your furnace, increasing its chances of breaking down prematurely.

For more information on heating maintenance and repairs, contact your local HVAC company.


Summer is Upon Us – Is Your AC Working?

Hi. My name is Laurie Waters. The HVAC contractor was just out at our house last week and did I ever get a lesson from him. You see, we had a warm spell hit and I went to turn our air conditioning on for the first time since last summer. Much to my dismay, it wasn’t working. All I got was a blast of warm air. The fan was bringing the outdoor heat inside. Thank goodness it wasn’t anything major. My unit needed Freon. While he was here, the contractor taught me how to do some routine maintenance around my unit, vents, and filters. I’m going to share this information with you. I hope you find it to be useful.

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