Variable Speed GE ECM Motors - When you look at buying a new HVAC system it will surely arise when the HVAC salesman or HVAC contractor who comes to give you an estimate will show an HVAC system that has a variable speed motor or the GE ECM (Electronically Commutated Motor) installed in it. These are systems that have a higher efficiency rating than the HVAC equipment that has the typical electric blower or condenser fan motor.

The ECM (Electronically Commutated Motor) uses less energy than the standard PSC motor that is commonly used in air handlers and condensers to move air. The ECM motor also offers more control which has good benefits in HVAC applications.

Variable Speed GE ECM Motors

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HVAC Motors That Save Energy - Variable Speed GE ECM Motors

GE or General Electric and Emerson (to name a few) produce variable-speed ECM motors for the HVAC industry. The HVAC manufacturer then takes these ECM motors and installs them inside their air handlers and condensing units. Not all ECM motors are variable speed. For example, in condensers, the motor has a fixed speed the same as many standard PSC motors.

The reason manufacturers use the more expensive ECM motor and run them at fixed speeds is because they use less energy than the standard PSC motors commonly used in condensing units. This allows the condensing unit to use less energy and gives the HVAC equipment a higher SEER rating.

Typically the ECM motors in the air handlers are variable speed but require a control board to control the speed to ramp up and down according to what the controller is calling for. The control boards can also be set to change the amount of air the ECM blower moves through the air handler.

This is commonly done with dip switches and gives the manufacturer a lot of flexibility for offering a single air handler that can accommodate different airflow capacities.

How the ECM Motor Works as a Blower – Variable Speed GE ECM Motors

Trane, Carrier, Rheem, York, and all the big HVAC manufacturers (and a few small ones also) have their own tagline for describing the ramp up and ramp down for the ECM blower motor.

The air handler will turn on and ramp to 50% (or whatever percentage the manufacturer deems appropriate) and then after so many minutes as determined by the program the ECM blower will ramp to 100%. When the thermostat satisfies the motor will slowly ramp down and then stop after so many minutes. This is often referred to as soft start and soft stop.

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The typical PSC motor starts and immediately goes to 100% and then stops almost immediately (aside from inertia) when the thermostat satisfies. The benefit of this is it can reduce humidity in the air when the unit first starts. This is important in the summertime when humidity levels are typically high in many geographical areas.

The less the humidity in the air the cooler you will feel. A big part of air conditioning is humidity removal and the variable ECM blower motor helps humidity removal when the motor is stepped up as described.

Efficiency Ranges and Other Factors for Variable Speed GE ECM Motors

Variable Speed GE ECM Condenser & Blower MotorsThe ECM motor (Electronically Commutated Motor) is preprogrammed to run at certain speeds as determined by the HVAC manufacturer such as Trane, York, Lennox, or Carrier. The first stage in the program is usually a lower speed in the cooling cycle to remove humidity.

A slower rate of an airflow across the evaporator coil allows the cold evaporator coil to remove the humidity in the air. The second stage of the ECM motor is usually 100% peak speed as designed for CFM’s and tonnage of the system.

From low to high speed the ECM (Electronically Commutated Motor) maintains a good efficiency range between 60% and 80% between all speeds versus the PSC motor with multiple windings getting between 10% efficiency at lower speeds to nearly 50% efficiency at higher speeds. As you can see that no matter the speed of the ECM it maintains efficiency and reduces the amount of electricity consumed to do the same thing the PSC motor does to move air.

Another bonus for the ECM motor especially in cooling mode is the fact that the temperature of the motor is constant and typically at or near ambient temperature whereas the operating temperatures of the PSC motor are 90 degrees F. to 170 degrees F. This means the air conditioner that uses the PSC motor must also overcome the heat generated and added to the system by the PSC motor while the heat added to the system with the ECM motor is nil to none.

Common Sense Protection for the Variable Speed GE ECM Motors

ECM motors are here and they offer a higher efficiency because they use less energy and provide benefits that the typical PSC motor cannot offer. ECM blower motors have been around for a while and have proven their reliability in HVAC applications. They are not trouble-free though as with any mechanical or electrical device problems can occur. To prevent some of the problems that occur it is recommended that surge protectors be used because of the solid-state controls that control the ECM motor.

Surge protectors can be purchased at most electronic stores and even some HVAC wholesalers offer surge protectors. By purchasing the air handler or gas furnace and condenser with an ECM motor you will consume less energy when your air conditioner or heating system is running. This means lower utility bills and more money in your pocket in the long run.

Variable Speed GE ECM Motors Additional Information:

  • Variable-speed ECM motors offer higher efficiency than other motors.
  • Variable-speed ECM motors if programmed and set properly improve system temperature, humidity, and capacity.
  • Variable-speed ECM motors can vary the speed based on input from a control board.
  • Variable-speed ECM motors enhance the efficiency of an HVAC system.
  • Variable-speed ECM motors offer slow start or soft start capabilities.
  • Surge protectors should be used on the circuit with Variable speed ECM motors.
  • Variable-speed ECM motors can be used in both the condenser and the air handler.

It is essential to gain all the benefits one can gain from these motors that they are programmed and set up properly. The programming part is up to the manufacturer while the setup part is up to the installer. This is why it is crucial to select a qualified and properly trained contractor to install your new system.

Other resources for Variable Speed GE ECM Condenser & Blower Motors can be found in our resources section below. High Performance HVAC also has additional HVAC Motor articles:

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Variable Speed GE ECM Motors