What Does a “Squirrel Cage” Have to Do with My Comfort System?

If you ever listen to HVAC repair technicians talk about the work they do, you may overhear a strange bit of jargon: talking about “the squirrel cage.” You may immediately have the silly picture in your heat of a squirrel running around in a wheel as the source of the energy for your air conditioner, furnace, or heat pump. Of course, your home’s comfort system doesn’t rely on squirrel-power (or the power of any other animal aside from the humans who first built it), but you may be interested to learn exactly what your technicians are talking about and why it’s important.

The squirrel-cage rotor

A squirrel cage refers to a type of AC (alternating current, not air conditioner) induction motor, and is sometimes called a squirrel-cage rotor. When connected to a motor, the set-up is called a squirrel-cage motor.

The configuration of a squirrel-cage rotor is a cylinder that is mounted on a shaft, which does make it resemble the running wheel you’d find in a rodent cage. The rotor contains copper or aluminum bars (the same bars that a squirrel would run along if it used the wheel). As the rotor spins, it induces an electric current in the conductive copper/aluminum bars. This current then reacts with the magnetic field of the motor connected to the rotor, and this produces the necessary torque to turn the shaft and run the motor. Basically, the rotor turns around with the magnetic field as the conductive bars interact with it.

So what’s this squirrel cage doing for my comfort system?

The main use of a squirrel-cage motor in a home HVAC system is that it powers the blower fan. If you have a forced-air heating system, such as a furnace, and/or an air conditioning system, the squirrel-cage motor is the part that turns the fans that blows the heated and cooled air through the ventilation system. It’s also a part that must be left to the care of HVAC professionals: don’t attempt to repair or replace one yourself!

When you need skilled heating or air conditioning repair in Fletcher, NC, call on Comfort Central, Inc.

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