If you have a gas or electric furnace heating your home in Mount Pleasant, SC or Charleston, SC, chances are you’ve heard some strange sounds coming from the unit at times. While some heater noises are totally normal, others can signal a bigger problem that requires professional HVAC attention. As your local heating experts, we want to help you interpret the most common heater sounds so you know whether it’s something to be concerned about or not.
Rumbling Noise When It First Turns On
This low, rumbling noise when you first turn your furnace on for the season or even just first thing in the morning is generally nothing to worry about. It comes from the initial combustion when the furnace burns fuel to create heat or from the fan motor and blower components spinning up to operating speed. This rumble tends to last only a few seconds to a minute or two and often quiets down once the entire furnace system is up and running.
Whistling or High-Pitched Squealing
A whistling, squeaking, or squealing noise, especially a high-pitched one, usually indicates a problem with your furnace blower motor, specifically the motor bearings. Motors rely on lubrication to spin smoothly. When the grease or oil lubricants wear thin or break down over time, motor components rub directly on each other, creating friction and noise. Have your HVAC technician lubricate or replace the blower motor before the squealing causes a full breakdown.
Intermittent Clicking Sounds
If you hear a distinct clicking noise coming from your gas furnace intermittently, this is likely caused by your ignition system producing sparks to light the burners. Older furnace models relied on standing pilot lights instead of electronic igniters. The igniter systems make clicking sounds on and off all winter long as they produce small sparks to relight the furnace each time it cycles on. This is completely normal so there’s no need to worry.
Most Common Heater Sounds Loud, Repetitive Banging or Clanging
Loud banging noises coming from your furnace, especially repetitive clanging sounds, typically indicate serious issues with the heat exchanger. The heat exchanger transfers heat from the burners to the blower to be circulated through your home’s ductwork. Cracks or holes in the exchanger allow combustion gases to leak and accumulate inside the unit. When the furnace starts up, these gases ignite and cause loud bangs or explosions. A damaged heat exchanger needs immediate replacement as it can leak dangerous carbon monoxide into your home.
Hissing Sounds Near the Burners
If you mostly hear hissing sounds localized to the burner area of your gas furnace, this points to a couple possible causes. Low gas pressure reaching your furnace can prevent the valves from closing completely. Gas then continues leaking from the burners in a long hiss even when the furnace shuts off. Low pressure usually results from blockages or bends in the gas line infrastructure leading to your home. The other possible cause is a faulty gas valve not sealing off the burners completely. Have your HVAC company check the gas pressure and valves and make any necessary repairs.
Water Trickling Sounds
Since most furnaces include air conditioning coils that produce condensation in warmer months, they have a drain system to remove this water. If you notice trickling water sounds coming from your furnace year-round, even during winter heating operation, this often signals a plugged condensate drain trap or tube. The water has nowhere to go and slowly builds up inside the furnace, potentially causing rust, electrical shorts, and other damage over time. Getting the drains cleared out and sealed to prevent future clogs is the solution.
Understanding Common Furnace Sounds
While hearing strange clanging, banging, and hissing coming from your furnace can be unsettling, not all sounds are warning signs of immediate trouble. We want you to recognize the difference between normal operating noise vs. critical red flags signaling it’s time to call a professional. Listen closely, document the specific noises you’re hearing and contact us anytime something seems seriously amiss with your heating system. We’re happy to assess the situation and let you know if repairs are required. With proper maintenance and care, your furnace can run smoothly and quietly for years to come. Call Mount Pleasant Heating & Air Conditioning 803-837-4115