5 Noises that Indicate Something Is Wrong with Your Furnace

HVAC Tech Inspecting A Gas Furnace

If your furnace is making strange noises, there could be a problem that requires professional attention. Noises are the most unmistakable sign that something is amiss, but not all noises mean the same thing. It’s essential to learn what different sounds mean so you can determine whether there’s a problem and, if so, what the problem may be. Correcting furnace noises could range anywhere from replacing furnace filters to a total system replacement. Check the list below to find out if the type of noise your furnace makes is a reason for alarm.

5 Common Furnace Noises

It’s essential to call an HVAC professional right away when you find your furnace leaking water. It helps to know a little about your furnace and answer the obvious question, “Why is my furnace leaking?” There are several reasons why a furnace might leak, but here are some of the most common reasons why. 

1. Clicking​

When a furnace makes a clicking noise, it could mean there’s an ignition issue. An ignition system is responsible for lighting the gas and creating the flame that heats the air. When ignition fails, a clicking sound is heard as the furnace attempts the process repeatedly. This can be caused by anything from dirty burners to an extinguished pilot light, and a trained HVAC technician should inspect it. 

2. Banging

A furnace making a knocking or loud banging sound can mean a few things. If the knocking and banging sounds appear when the furnace starts running, they could be from expanding air ducts. Objects shrink when they’re cold and expand when they’re warm. The same happens to air ducts. As warm air starts to pass through them, they expand to accommodate the new temperature, which creates a popping noise.

Banging sounds could also mean there’s an ignition problem. This could be the issue when a furnace doesn’t turn on right away and starts running after making a loud popping sound. Delayed ignition causes a build-up of gas in the heat exchanger. When it finally ignites, it causes a small explosion that harms the furnace. Like before, the ignition issue could be caused by dirty burners, slow gas supply, or improper flow. It’s enough of a concern to have an HVAC contractor inspect it before the problem gets worse.

5 reasons for furnace making noise infographic

3. Humming

Furnaces naturally emit a low noise when they are running. A furnace making a humming noise louder than usual often points to a blower fan or motor problem. This is typically an electrical issue that can be remedied by replacing or treating an old blower motor or its capacitor. If the sound persists and gets increasingly louder, it’s best to call a technician to diagnose the problem properly. 

4. Whistling

Whistling sounds often mean there’s restricted airflow. Check your furnace for clogged or dirty filters. Inspect your ductwork for any obstructions that could be affecting the circulation of air. If all vents have been opened, the filter has been replaced, and the sound persists, it’s time to call a technician for further assessment. 

5. Rattling

Most furnaces are big and bulky and require many parts to stay in function. Those parts can get old and worn, leading to loose parts in the furnace. Loose parts could cause a rattling sound. Things like bearings, panels, and, in older systems, belts can become loose or aged and require replacement. 

Loose pieces can also break other parts of the furnace, such as blower motors, igniters, heat exchangers, and gas burners. Once the rattling spreads or worsens, it probably means the problem is spreading too. 

If the rattling is high-pitched and happens when the furnace first comes on, it could be a broken heat exchanger. Just like the air ducts expand when warm air starts to blow, the coils expand and make a rattling noise when the heat exchanger is cracked or has a leak. This is an immediate cause of concern, and it should be addressed before the problem magnifies as the repairs for heat exchangers get costly. 

Air Pro Heating and Cooling

When you hear strange furnace sounds, it’s best to get it checked out immediately. The longer you wait, the more time you give for the problem to worsen. Air Pro Heating and Cooling has trusted HVAC technicians ready to be dispatched to service your furnace equipment and all your heating and cooling needs. Contact us today to schedule a visit and see why we’ve been in the air conditioning business for two decades. 

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