97 • dap4 User Manual
option turned on, the fan will operate at minimum fan speed when the valve is fully open and at
maximum fan speed when the valve is fully closed.
4. Static Pressure Constant (Air Pressure) - Optional
In Static Pressure Constant mode, a differential pressure (DP) transducer is required and
connected to dap4 module to report the differential pressure across the unit (between supply
and return air section).
When started in this mode, the fan will first operate at the constant speed set in CW Speed for
5 minutes. After that, the fan will proportionally increase or decrease the speed to maintain the
constant static pressure setpoint set in Static Air Pressure menu page, and the deadband set in
static band.
5. Airflow Constant (Const. flow) - Optional
This option requires a factory installed airflow flow measurement kit and programming.
On units where constant design airflow is required, an airflow value is entered into airflow SET
POINT on FAN AIR FLOW menu. In this mode, the fan will start and operate at this constant
design airflow all the time.
6. Airflow Controlled by BMS (BMS Flow) - Optional
In Airflow Controlled by BMS mode, the dap4 will start and operate the fan at the constant air
flow set in air flow setpoint in Fan Air flow menu until the dap4 receives a valid airflow value
(greater than the minimum allowed airflow and less than the maximum allowed airflow) from a
BMS. This control mode requires an optional airflow measurement kit.
The airflow will automatically increase to the maximum airflow set in Maximum Flow when
reheat or humidification is required. The airflow will revert to the BMS controlled airflow setting
when the unit stops calling for reheat or humidification.
WARNING: IF CUSTOMER DECIDES TO USE THIS FAN SPEED CONTROL MODE (AIR
FLOW CONTROLLED BY BMS), DATA AIRE WILL NOT BE RESPONSIBLE FOR ANY
EFFECTS, MALFUNCTIONS OR SPACE CONTROL CONDITIONS CAUSED BY THIS
SELECTION.
7. Airflow Proportional to CW Valve (Vlv. Pos. Flow) - Optional
On units where proportional fan airflow control based on the CW valve position is required, the
maximum airflow is programmed via Maximum Flow menu, and the minimum airflow as a per-
centage of the maximum airflow is programmed via Minimum Flow menu in Fan Air flow setting.
This control mode requires an optional airflow measurement kit.
When the fan starts, it will operate at the minimum airflow value. As the chilled water valve
opens, the fan airflow will modulate proportionally based on the CW valve position from the
minimum airflow (when the CW valve is fully closed) to the maximum airflow (when the CW
valve is fully open).
The fan will operate at the maximum airflow when the unit calls for reheat or humidification.
