If your furnace is old, it's probably not very efficient. One factor that contributes to efficiency is the furnace's motor. In the past, motors in furnaces were AC induction motors that used a lot of energy because they ran at full speed all the time. This also contributed to another problem: loud running noise. Today, however, more efficient furnace motor options are available. For instance, a furnace with a electronically commutated motor, or ECM, is a much better choice.
Benefits of an ECM Motor
ECM motors can save up to 75 percent of energy used when compared with older motors. You also have more flexibility with certain efficient furnace motor options.
- You can choose one motor type for the condensor and another for the air handler.
- Typically, a single speed ECM is put in the condenser and a variable speed ECM is put in the air handler.
- In addition to greater flexibility, there are other reasons why ECMs are more efficient and give furnaces a higher SEER rating (seasonal energy efficiency ratio). ECM motors run on DC, which makes operating them cheaper. AC goes in and a rectifier changes it to Direct Current.
- ECM motors have a built-in inverter and a magnet rotor.
- ECMs are easily programmed by the manufacturer. For example, the manufacturer can decide what percentage of full speed the motor will start out with. Then after a certain number of minutes, the motor will kick into full speed. This is called a soft start and this can reduce energy costs.
- A soft stop also saves energy because, when the thermostat signals the motor, it will slow down and then stop, rather than halting suddenly. Even working at a fixed speed, an ECM still works more efficiently than older motors.
