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Five Common Causes Your Furnace Makes Loud Noises

Achieving comfortable indoor air is one of the priorities, and a furnace can make that happen. Considered a forced-air system, a furnace utilizes the ductwork and allows users to install an air filtration system, humidifier, dehumidifier, and air purifier right into the system. So, instead of using multiple spot conditioning systems, you can have it all in your furnace system.

These heating systems are also known for their efficiency and ability to heat a room fast. And when it comes to costs, furnaces are cost-effective. The initial cost might be high, but you can offset that quickly, considering the given perks and long-life expectancy. But to keep it in good shape and high efficiency, you need also to get some maintenance work done. A straightforward way to do that is to notice any noises it’s making. Learn more about what these noises are, their causes, and the actions you need to take.

basement home furnace unit with cover off.

1. Clogged filter

Is there a whistling sound coming from your heating system? That might be a sign of a restricted airflow in the furnace caused by clogged filters. You can check if your furnace filter is clogged with dust or dirt by turning off your system and removing it. In some cases, a good cleaning will do. Or, you might need a replacement, especially if the filters are already worn out enough. Using a new filter can mostly guarantee that the whistling sound will disappear. Note that this is an internal furnace repair, so it’s best to let the professionals handle it.

2. Dirty burners

If you hear a loud boom or bang whenever you turn your furnace on, there’s a possibility that the burners are dirty. Failing to clean the burners regularly can cause delayed ignition then gas build-up. That is when the exploding or boom sound starts. It is highly recommended to call on a local heating technician for a tune-up. They can provide regular inspections and cleanings to your furnace burners, preventing gas build-up. Experts can also ensure that there wouldn’t be an unbalanced air-to-fuel ratio, which can cause a loud boom or bang.

3. Gaps in the duct

Gaps in the air duct, usually appear to be small holes, can cause your unit to produce a whistling sound. Leaks on the air duct are usually a result of poor connections to the ducting trunkline and deterioration of the ductwork itself. These are common issues with an old HVAC system. These leaks will not just generate a whistling sound but can also waste energy and increase your bills. In most cases, you can use high-standard HVAC foil tape to cover up the gaps and fix the whistling sound. You can also seal them off using clear hi-temperature silicone. Sealing up different junctions in the air duct can improve the efficiency of your heating unit.

4. Out-of-balance blower wheel

An out-of-balance blower wheel can cause your system to produce the same sound your washing machine does. It’s important to get this fixed right away, leading to more issues. It can affect your overall HVAC system. An out-of-balance wheel is typically caused by materials like tissue or paper getting sucked into the air duct. This happens when you attempt to change the unit’s filter while it’s still running. Another possible reason is that a balancing weight has fallen from the wheel. Call on an experienced heating technician for a complete system inspection.

5. Crack in the heat exchanger

The last on our list is probably the most severe problem your unit can have. If the heat exchange has a crack, it’s highly advisable to stop using it until it’s fixed. Instead of safely venting the carbon monoxide outdoors, the crack can cause it to get mixed into your indoor air. This can generate deadly carbon monoxide indoors, which can endanger your and your family’s health. A cracked heat exchanger will produce a rattling noise or a clink. Other heating units will generate a low-pitched rumble, which you should watch out for too. If you hear any of these sounds, immediately call on an emergency furnace technician to inspect it.

With as little as listening to the noises your furnace is making, you can save yourself from more expensive repairs or even a replacement. If you’re not that handy or skilled in such a task, let the experts do it to avoid causing further problems to your furnace. Maintain your system’s high efficiency by hiring a heating and cooling professional.


About Julee: Julee Morrison is an experienced author with 35 years of expertise in parenting and recipes. She is the author of four cookbooks: The Instant Pot College Cookbook, The How-To Cookbook for Teens, The Complete Cookbook for Teens, and The Complete College Cookbook. Julee is passionate about baking, crystals, reading, and family. Her writing has appeared in The LA Times (Bon Jovi Obsession Goes Global), Disney's Family Fun Magazine (August 2010, July 2009, September 2008), and My Family Gave Up Television (page 92, Disney Family Fun August 2010). Her great ideas have been featured in Disney's Family Fun (Page 80, September 2008) and the Write for Charity book From the Heart (May 2010). Julee's work has also been published in Weight Watchers Magazine, All You Magazine (Jan. 2011, February 2011, June 2013), Scholastic Parent and Child Magazine (Oct. 2011), Red River Family Magazine (Jan. 2011),, and more. Notably, her article "My Toddler Stood on Elvis' Grave and Scaled Over Boulders to Get to a Dinosaur" made AP News, and "The Sly Way I Cured My Child's Lying Habit" was featured on PopSugar. When she's not writing, Julee enjoys spending time with her family and exploring new baking recipes.
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