IM 830-6
58 www.DaikinApplied.com
Controls by Others - Variable Airflow
An EC motor with optional “variable fan speed control” allows
a field provided DDC controller to modulate the unit airflow
between 50% and 100% of nominal unit airflow in a single zone
variable air volume sequence. In continuous fan mode the
benefits of Single Zone VAV include sound reduction, energy
savings, and consistent and precise temperature control for
improved comfort with better air mixing and less stratification.
In humid climates, the ability to deliver a wide range of fan
speeds is particularly effective for de-humidification.
Note:
This option is not available with MicroTech controls.
Making Control Connections
For field provided control wiring connections refer to the
appropriate control wiring schematic,
Connect the field supplied controller to the harness provided. A
0-10VDC fan control signal must be provided between ground
and wire 33. For RPM/data out signal, connect controller to
wire 34.
The variable fan speed scale is linear between a minimum
50% airflow at 2vdc and a maximum 100% airflow at 10vdc
as shown in
. Reducing the input signal to 0vdc will
cause the motor to turn off. Care should be taken when using
variable airflow on units with DX cooling as lower airflow may
increase the risk of coil freeze-up. Variable airflow control
should not be used on units with electric heat.
Figure 97: 0-10VDC Variable Fan Speed Control
10
100
8
4
2
6
50
60
70
80
90
0-10 VDC Control Signal
% Nominal Unit Airflow
0