High Performance HVAC Technicial Articles - GE ECM Electronically Commutated Motor for HVAC Blowers and Condensers

 

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GE ECM Electronically Commutated Motor for HVAC Blowers and Condensers

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 mover air. The ECM motor also offers more control also which has good benefits in HVAC applications.

GE or General Electric produces these 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 give 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 air flow capacities.

Trane, Rheem, York, and all the big manufacturers (and a few small ones also) have their own tag line 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. 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 summer time when humidity levels are typically high in many geographical areas.  The lesser the humidity in the air the more 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.

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 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 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 wholesaler’s 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.

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