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Replace Oversized Motors To Reduce HVAC Energy Use

Today's tip from Building Operating Management comes from James Piper, contributing editor to Building Operating Management and Maintenance Solutions magazines: Replace oversize motors to reduce HVAC energy use.

Commercial and institutional facilities typically have many more motors operating in their HVAC systems than most managers realize. Because these motors use so much energy, they offer great opportunities to make a significant impact on facility energy use.

By far the leading cause of energy inefficiency with HVAC system motors is a mismatch between the motor's rated horsepower and the load it is driving. Most HVAC system motors are induction motors.

While these motors are efficient and reliable, their efficiency, like building chillers, drops off significantly when they operate under part-load conditions. By properly matching motor horsepower to system load requirements, managers can achieve major energy savings.

Achieving this goal requires that managers conduct a survey on HVAC system motors to identify those that are significantly oversized for the application. The goal of the process is to develop a comprehensive list of applications that use motors, including information on the motor horsepower, the load it is driving, and the age and rated efficiency of the motor.

The focus should be on motors that are oversized or have exceeded their operating life expectancies.

Replacing older, oversized motors with properly sized ones offers two benefits. First, matching the motor horsepower to the actual load improves the operating efficiency of the system.

Second, changes in motor design have resulted in a generation of motors that have operating efficiencies 2-8 percent higher than older, standard motors. Coupled with the improved operating efficiency that comes from matching the motor horsepower to the load, the improvement in efficiency can provide a relatively quick payback for managers and facilities.

This has been a Building Operating Management Tip of the Day. Thanks for listening.


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