When a system is equipped with an External Rotor Motor (ERM), the minimum and maximum ERM
parameters can be adjusted to tune the airflow to meet the application requirements.
In addition to this, the Symbio™ 700 supports setpoints that can adjust airflow as needed:
• Supply Fan Maximum Speed Setpoint
– Range: Determined by unit tonnage. See the table below.
– Operation: This setpoint “trims” the maximum fan speed, based on the configured maximum
ERM rpm.
– Example: rpm max = 1940 rpm
• Supply Fan Maximum Speed Setpoint @ 75% yields a maximum of 1358 rpm ERM output.
• Effective ERM Max (to be used in Supply Fan Minimum Speed Setpoint application) will be
set to 1358 rpm.
• Supply Fan Minimum Speed Setpoint
– Range: 0-100%
– Operation: 0-100% over the minimum to effective maximum ERM configured fan speed
– Example: ERM Min = 0 rpm, Effective ERM Max = 1940 rpm
• Supply Fan Minimum Speed Setpoint @ 50% yields 970 rpm ERM output.
• Minimum and Maximum Speed Setpoints interact to ensure that the minimum defined fan speed at a
given equipment operating condition is maintained.
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WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.