5 Strange Heater Sounds & What They Mean

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The occasional sound from your heater or furnace is no cause for alarm, but if you’re noticing unusual sounds or if the heating system just started making sounds, it may be time for heater repairs. Check out this list of furnace noises to determine what might be the cause and if it’s necessary to call an HVAC company.

A broken heater is nothing to ignore! When you need heater repairs or maintenance, contact Bloomington Heating & Air for prompt and dependable service. Schedule an appointment today.


When you first turn it on, a furnace humming or even intermittent soft humming as the furnace changes currents is no cause for concern. However, a heater making loud noise is unusual and should be inspected promptly. If the humming occurs beyond the initial start-up, it could be a fan wearing down, and a technician should be called to replace it.


A whistling furnace usually indicates something is blocking the airflow. You can troubleshoot this issue on your own by checking and replacing the air filter, ensuring all vents and dampers are opened and unblocked, and cleaning the air ducts. If the furnace is still whistling, it may indicate a more serious issue, such as with the burner or blowers. If your furnace has always whistled, it may not be the right size for your home or ductwork. In this case, a new furnace installation can save you money and stop the annoying whistling.


A gentle whooshing or even a soft roaring sound when the furnace turns off is no cause for concern. However, if the furnace rumbling continues after the unit is off, there may be an issue with the burner where oil or gas is still in the combustion chamber. This should be taken very seriously, as the extra fuel in the combustion chamber can result in carbon monoxide in your home. If your furnace is rumbling after turning off, call an HVAC technician immediately for emergency heater repairs.


A furnace banging when you first turn it on may indicate an issue with the ignition. There are several reasons that the ignition may not be functioning properly, such as dirty or clogged burners, a weak flame in the pilot light, or an issue with the electrical system if there is an electronic ignition. HVAC maintenance can help catch these problems before they cause issues with the heating system.


The furnace rattling or making a metallic scraping sound is often a sign something is loose, usually your blower fan, and needs to be inspected as soon as possible so repairs can be made. If left alone, the fan’s blades or another loose part could cause irreparable damage to the rest of the heater.

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