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DN-Series Integrated Programmable Controls
DOAS
UNIT OPERATION
5.0 UNIT OPERATION AND FAN CONTROL
5.1 SEQUENCE OF OPERATION FOR UNIT START
The primary purpose of the DN DOAS Unit is to provide 100% OA. The amount of air that it
provides is based on the configuration of the supply and exhaust fans and whether the unit is
running or not.
Fans are either controlled with variable speed drives or ECM motors.
The unit will start when all of the following conditions are true:
u
There are no serious alarms.
u
The Digital Input for start/stop (terminals 17 and 18) are closed.
u
The unit is turned on at the keypad.
u
The time is within the scheduler “ON” time, if scheduler enabled.
u
The BMS has written the unit on signal, if BMS control is enabled.
Upon starting, the isolation dampers will open. The end switches of these dampers will
complete the Fan Enable signal to the ECM or VFD fans.
Once the fan enable signal is complete, the fan command signal will be sent to the fan after
the start up delay time. Each fan is paired with a current sensor. If within the alarm delay time,
default 90s, the current sensor does not detect the fan running, the unit will shut down and an
alarm will occur.
The setting
SF Alarm Unit Run?
setting tells whether the unit, and thus the exhaust fan, will
continue to run if there is an alarm with the supply fan.
The Unit status is shown on the bottom of this screen. More than one of these statuses may be
valid at one time
