I believe the Difference is in the PSC the torque is dependent upon the static pressure and air flow varies with the torque. Whereas in the ECM the torque is dependent upon desired design air flow, the air flow is set and the torque is applied depending upon the static pressure. At initial startup it's essentially a PSC, it knows the static pressure by the measured amperage, then the factory parameters set within tell it to increase torque to meet the design flow. The difference is the PSC is riding the fan curve (no ability to correct it's performance), the ECM is riding the system curve and is 20-30% more efficient in it's operation.
So, The home owner is the one keeping the furnace or air conditioner in efficient if they don't change the filter on a regular basis and keeping registers closed. PSC motors are more reliable than ECM.
in a furnace you measure the total external static pressure before the evap coil and within a foot of the blower. for an air handler right at the return and supply ducts.
The best video to explain variable speed ecm motor!
Thank you.
I still don't see the difference between a constant torque and a constant air flow. They seem to both try to achieve a certain torque
I believe the Difference is in the PSC the torque is dependent upon the static pressure and air flow varies with the torque. Whereas in the ECM the torque is dependent upon desired design air flow, the air flow is set and the torque is applied depending upon the static pressure. At initial startup it's essentially a PSC, it knows the static pressure by the measured amperage, then the factory parameters set within tell it to increase torque to meet the design flow. The difference is the PSC is riding the fan curve (no ability to correct it's performance), the ECM is riding the system curve and is 20-30% more efficient in it's operation.
So, The home owner is the one keeping the furnace or air conditioner in efficient if they don't change the filter on a regular basis and keeping registers closed. PSC motors are more reliable than ECM.
A dirty filter can take out a PSC too. Obviously the more complex the motor, the more that could go wrong with it. ECM are far better.
The only thing that is constant in my $8K brand new furnace is a motor whine noise...I hate it. We are in talks with the tech....
Where are the best spots to take the static pressure ? How close to the fan ?
Measure differential Within a few feet of the fan and outside duct pressure to get static
@@areuokdaie You never go outside the furnace or air handler cabinets to get duct pressure.
in a furnace you measure the total external static pressure before the evap coil and within a foot of the blower. for an air handler right at the return and supply ducts.
Ja!