Supply Fan Speed Control; Single-Speed, Belt-Driven Fans; 2-Speed & Variable Speed Vfd-Driven Fans; Supply Fan Status Points - Trane SYMBIO 700 Troubleshooting Manual

Supply Fan Speed Control

At the initial launch of the Symbio 700 for Odyssey equipment, three supply fan types are supported:

Single-Speed, belt-driven fans

These fan types are controlled ON/OFF via a single binary output on the Symbio 700.
2-Speed & Variable Speed VFD-driven fans
These fan types are controlled via Modbus through a wired communication link (except for air-handlers
paired with non-Trane or legacy Electromechanical condensers)
At all times, a minimum fan speed will be maintained based on equipment design requirements.

Supply Fan Status Points

Single-Speed

Supply Fan Output Status - Indicates whether the fan is commanded ON or OFF
Supply Fan Speed Status - 0% when fan is OFF, 100% when fan is ON

VFD-driven

Supply Fan Output Status - Indicates whether the fan is commanded ON or OFF
Supply Fan Speed Status - Estimated active fan capacity from 0-100%. 0% = OFF, 100% = Maximum
Speed per application
Supply Fan Signal Command Status - Modbus signal command to VFD; 0% = Minimum Configured Drive
Speed, 100% = Maximum Configured Drive Speed
Status points will reflect accurately but can be impacted by VFD setup and setpoints.

Fan Setpoints with VFD-driven Fan Types

When a system is equipped with a VFD, the minimum and maximum VFD parameters can be adjusted to
tune the airflow to meet the application requirements.
In addition to this, the Symbio 700 supports setpoints that can be used to adjust airflow as needed:

Supply Fan Maximum Speed Setpoint

Range: 67-100%
Operation:
This setpoint "trims" the maximum fan speed, based on the configured maximum VFD speed
Example: VFD Max = 60Hz
Supply Fan Maximum Speed Setpoint @ 75% yields a maximum of 45Hz VFD output.
Effective VFD Max (to be used in Supply Fan Minimum Speed Setpoint application) will be set to 45Hz
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