Now, on a call for cooling, the motor turns on and is going to try to maintain your programmed CFM. (Always use the manufacturer’s tables for setting up an ECM motor). You use the programming board and set BOTH the cool and adjust profiles for as close to 1200 CFM as you can. So we need 400 CFM per ton or 1200 CFM to work properly. “Let’s say you have a 3 ton air conditioner. I found an article from our friends at York that gave a “real-world” example of how ECMs work.
What is ecm in car full#
And since you don’t NEED the motor to run at full speed all the time, it’s a no-brainer energy savings technique! So any time you can slow it down, even a little, saves you big bucks. A motor running at full speed uses nearly 8 times the energy of a motor running at half speed. When it is not needed at full speed, the motor can slow down, which uses far less energy. The energy savings come into play when demand and static pressure decreases. The control board dipswitch settings (usually set in the field) need to be set up properly for proper seasonal operation. * Ideal airflow will be different in heating and cooling modes. At the same time, increased airflow also provides the additional oomph of airflow that the system needs to provide additional cooling or heating capacity during high demand times for the system. More airflow also reduces static pressure, which reduces torque. A faster motor creates more airflow to make sure that CFM stays steady despite the resistance in the system from conditions like clogged filter or a hard-working evaporator. When the microprocessor senses increased torque, it automatically increases the speed of the motor. Higher pressure essentially creates additional resistance on the blades of the fan motor, which is why it needs more “muscle” or torque to turn the motor. An increased torque basically means that it requires more “muscle” to turn a motor. This higher pressure increases the torque on the motor. Resistance to air flow can also be caused by a clogged filter or dirty coil, which will also increase static pressure. Higher cooling demand increases condensation on the evaporator coil, reducing air flow (hence higher static pressure). When the load or demand on the system increases (like it’s really hot outside, for example), a higher static pressure is present. We couldn’t figure out what could initiate a change in torque? It turns out it’s static pressure in the system. This was where me and the folks in my office really got stuck. Depending on system conditions, the motor will need to spin faster or slower in order to keep a steady torque and airflow. What WILL change is the speed of the motor (RPM). Once the settings are programmed into microprocessor in the factory and the control board dip switches are set in the field, the motor torque and airflow (CFM) should remain steady*. When ordering a replacement ECM motor, techs must know the specs of the model in which the motor will be installed for it to work properly. It should be noted that the ECM motor programming is specific to each model of HVAC equipment, so programming is ONLY done at the factory, not in the field. The logic is a math equation or algorithm that figures out the ideal airflow for each specific piece of HVAC equipment out there and uses a formula to maintain that airflow using a calculation of the precise relationship between motor speed and torque. It holds the logic that controls the motor. The microprocessor is the “brains” of the motor.
But for ease of discussion, I’m going focus on a Constant Torque ECM motor.Ī Constant Torque ECM is made up of two parts, the motor and ECM Microprocessor, that are both housed in one shell. Since cfm, rpm and torque are all related, the basic prinicples are the same. Without a VFD or external sensors to monitor pressure, temperature, or anything else, how the heck does the motor know when to speed up and when to slow down?ĮCM stands for an “electronically commutated motor” which basically means a motor that uses electronic controls to vary its speed. There are three types of ECM motors: constant cfm, constant rpm, and constant torque. The general consensus was that although we were familiar with the concept behind them – they are motors that regulate their own speed without the help of an external VFD or other device – none of us really understood the magic behind what makes an ECM Motor actually work. Yeah, we have weird water cooler conversations like that. Several of us were discussing ECM motors in the office the other day.