A furnace making a loud noise is more than just an annoyance. It could be a warning sign that something is wrong. Whether it's a bang, rattle, screech, or hum, unusual furnace sounds deserve your attention. Here's what those noises might mean, whether a loud furnace is dangerous, and when it's time to call in a professional.
Common Reasons Your Furnace Is Making a Loud Noise
- Banging or booming: Usually caused by delayed ignition, where gas builds up before igniting. Repeated occurrences can crack your heat exchanger, a costly and potentially dangerous repair.
- Rattling or vibrating: Often points to loose panels, screws, or ductwork, but can also indicate a cracked heat exchanger that may allow carbon monoxide to escape.
- Screeching or squealing: Typically signals a worn blower belt or failing motor bearings—mechanical issues that worsen without attention.
- Rumbling: A low rumble after the burners shut off often points to a dirty burner or pilot light issue that warrants a professional look.
Is a Loud Furnace Dangerous?
A possible danger depends on the cause. Some noises, like a loose panel, are minor. Other noises, such as banging from a delayed ignition or rattling from a cracked heat exchanger, can pose serious safety risks, including carbon monoxide exposure. If you notice a furnace making weird noises alongside symptoms like headaches, dizziness, or a yellow burner flame instead of blue, treat it as an emergency and ventilate your home immediately.
What Is Emergency Heat, and Is It Related?
You may have a heat pump system with a thermostat that includes an "Emergency Heat" or "Em Heat" setting. Emergency heat is a backup heating mode that bypasses your heat pump and relies solely on the auxiliary heating element. It's designed for situations when your primary system fails or struggles in extreme cold.
Running your system on emergency heat for extended periods is inefficient and hard on your equipment. If you find yourself switching to emergency heat frequently or notice your furnace making loud noises around the same time, that's a sign your system needs professional attention.
When To Call a Professional
Some furnace noises call for immediate action. Reach out to one of our HVAC professionals if:
- Your furnace is making a loud banging or booming noise at startup
- You hear persistent rattling that doesn't come from a loose panel
- The noise is accompanied by reduced heating performance
- You've been relying on emergency heat more than usual
- You suspect a cracked heat exchanger or carbon monoxide leak
Routine maintenance can also prevent many of these issues before they start. Regular system checkups improve efficiency and extend the life of your equipment.
Let Barnard Heating and Cooling Take a Listen
Barnard Heating and Cooling is a family-owned HVAC contractor serving Carthage, Missouri, and the surrounding communities. Whether your furnace is making a weird noise or you just want peace of mind in the colder months, our team is ready to help. Schedule your free estimate today and let Barnard Heating and Cooling keep your home comfortable all season long.