Variable Speed GE ECM Condenser & Blower Motors | HVAC Control 5/5 (1)

Variable Speed GE ECM Condenser & Blower Motors

Variable Speed GE ECM Condenser & Blower 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 mover air. The ECM motor also offers more control which has good benefits in HVAC applications.

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HVAC Motors That Save Energy – Variable Speed GE ECM Condenser & Blower Motors

Variable Speed GE ECM Condenser & Blower Motors
Variable Speed ECM Blower Motor

GE or General Electric and Emerson (to name a few) 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 runs 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.

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How the ECM Motor Works as a Blower

Trane, Carrier, Rheem, York, and all the big HVAC 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 less 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.

Efficiency Ranges and Other Factors for the ECM Motor

Variable Speed GE ECM Condenser & Blower MotorsThe ECM motor (Electronically Commutated Motor) is preprogrammed to run at certain speeds as determined by the HVAC manufacture 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 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 temperature of the motor is constant and typically at or near ambient temperature whereas the operating temperatures of the PSC motor is 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.

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Common Sense Protection for the ECM Motor

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 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.

Variable Speed GE ECM Condenser & Blower Motors Additional Information:

  • Variable speed ECM motors offer a higher efficiency than other motors.
  • Variable speed ECM motors can vary the speed based on input from a control board.
  • Variable speed ECM motors enhances the efficiency of an HVAC system.
  • Variable speed ECM motors offers 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.

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9 thoughts on “Variable Speed GE ECM Condenser & Blower Motors | HVAC Control

    • Yes as long as you maintain the proper RPMs of the old motor and do not exceed the temperature limitations of the safety limits. For a novice I do not recommend it.

  1. Is there any particular surge protector rating that you would recommend? Any particular surge protector brands?

    My ECM failed due to a surge at least that is what I am being told. We definitely smelled a plastic/rubber smell the night before.

    Really good information on your site.

    • It really depends on the type of system you have but you can purchase the surge protectors that go in the main electrical panel and will protect whatever circuit or range of circuits you have installed in the panel. If you have a heat pump then you have a larger circuit than you would for an air conditioner as most heat pumps have electric heat strips. The best thing to do to properly protect the system is to take a load calculation of the system and protect everything from the main panel.

  2. I have a Trane air handler model TWE031E13FBO. The ICM motor starts up and as it ramps up in speed I get a sudden buzzing sound and the motor turns off and then repeats this cycle . I was hoping to get advice on what part would be the culprit ?
    ICM Fan control board?
    Motor Module?

  3. I have an Armstrong Air handling unit with an ECM motor, I do not believe it is variable speed, The ECM module is dead on my motor, the motor is only sold as one piece and its 1,100 dollars to replace, Can I replace my ECM motor with a different motor that has the same ratings as the original…

    • Yes you can but you will lose efficiency, mess up any warranty, and potentially cause lots of other problems. You also have to make sure you get RPM’s correct otherwise you will have problems with the evaporator coil freezing or other issues with the refrigeration system. Not sure what the RPM’s of the new motor should be as the are different motors for different air handlers for blower speed and it depends on the blower wheel and some other factors. The most important part is get the proper amount of CFM’s across the evaporator coil otherwise you will cause more problems than not. The wiring for a technician should be pretty cut and dry. You will likely have to add a relay to control the blower if you convert it. Honestly, I do not recommend it unless you really know what you are doing. I know it can work and save you money but I would not do it myself unless I had specific written instructions from the manufacturer.

  4. I have a carrier unit I have replaced the existing ECM motor was a GE 3.0 ECM I put in a new ECM motor however the furnace is looking for a signal that the motor is running at 250 rpm’s my furnace is locked out because it does not receive signal from new motor I have is a Genetech replacement for the Ge

    The old motor had a common 2 speed Rx TX. And a v+. The new motor has a common and 4 speed wires. No V+ . I believe the v+ is a 24 V output from the motor. Any ideas

    • Rule of thumb especially with electronics and especially with certain manufacturers like Carrier and Trane is to use an exact replacement. Carrier parts are typically proprietary (which makes them expensive) so you may have to either re-engineer (not recommended) or go to Carrier or a Carrier dealer for the right part.

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