The existing fan coil units are equipped with either three-speed fractional horsepower shaded pole induction motors and with 3-speed switches, or permanent split capacitor (PSC) induction motors in combination with electronic SCR speed controllers. These factory-standard technologies are low first-cost items, but are very inefficient in operation. Because they are typically turned down to achieve sound level targets, installed PSC motor efficiencies are typically in the range of only 12 – 45%.
ECM (Electronically Commutated) motors are high efficiency programmable brushless DC motors utilizing a permanent magnet motor and a built-in inverter. As the cost of the electronic inverters has declined and the reliability has improved, this technology has become much more practical and affordable. ECM motors maintain an efficiency of 65 – 72% at all speeds.
Average 90,000 hours MBTF (mean time between failure), versus 50,000 hours for a typical PSC motor. This translates into about 10 years for a typical fan coil as opposed to 8 years for a unit using a PSC motor.
Soft starts programmed into the ECM motor reduce stress transmitted to the mounting bracket or hardware.
Issues and Concerns
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