The term "bearing" comes up in a variety of contexts, but it may be unfamiliar to you if you don't have much experience with mechanical equipment. Mechanical bearings allow two parts to move together while minimizing the friction between them. Without bearings, electrical motors and even the wheels on your car would be unable to spin smoothly and without the need for constant part replacements.
In your furnace, you find bearings helping your fan motors spin smoothly and quietly. When a bearing fails, you will usually very quickly notice that something is wrong. Recognizing the signs of a bearing failure can help you to address the problem before it leaves you without heat for the winter.
The Role of Bearings in Your Furnace
Depending on your furnace design, bearings will play a key role in one or two locations: the air handler motor and the draft inducer motor. If you picture the central hub of a fan, it's easy to see why your HVAC air handler blower requires bearings to function. As the motor turns, the bearings allow the fan blades to spin inside the housing.
If you own a furnace with a draft inducer, then bearings play a similar role in the operation of this smaller fan. Your furnace's draft inducer helps to clear away exhaust gases trapped in the heat exchanger, so this unit only runs when the furnace first turns on.
The Signs of Bearing Failure
Bearing failures can be noisy and disruptive, and you will often notice the sound before a failure negatively impacts the operation of your furnace. If your air handler bearings are beginning to wear out, then you may hear a low hum or grinding noise whenever your fan runs. As the problem worsens, the grinding may progress to squealing, and the fan will eventually stop running.
Bad bearings in your draft inducer will produce similar symptoms. Since the draft inducer only runs for a short time, you may only notice these noises for a minute or two after the furnace turns on.
The Causes of Bad Bearings
Under normal circumstances, the bearings in your air handler and draft inducer should last for the life of your furnace. Early failures typically result from poor maintenance habits that allow the air handler motor to overheat. When your air handler overheats, the grease in the bearing "cooks," ultimately reducing its effectiveness. Without proper lubrication, friction will quickly destroy the bearings.
If you believe that your air handler is suffering from a bearing problem, always contact an HVAC professional as soon as possible. Not only will bad bearings eventually cause your system to seize up, but leaving the problem for too long can ruin your air handler's motor. Addressing the issue is the best way to save money and restore the functionality of your furnace. Reach out to a professional to learn more about furnace repair.