96 • dap4 User Manual
1. Speed Constant (Const. Speed)
2. Speed Controlled by BMS (BMS Speed)
3. Speed Proportional to CW Valve (Vlv. Pos. Speed)
4. Static Pressure Constant (Air Pressure)
5. Airflow Constant (Const. flow)
6. Airflow Controlled by BMS (BMS Flow)
7. Airflow Proportional to CW Valve (Vlv. Pos. Flow)
8. Fan speed controlled by Return air temperature setpoint (Mod to R. Air)
9. Mod to Rack
1. Speed Constant (Const. Speed) - Default
In Speed Constant mode, the dap4 will start and operate the fan at the constant speed set in
CW SPEED. The constant speed is controlled by outputting a constant voltage to the fan
speed controller.
2. Speed Controlled by BMS (BMS Speed)
In Speed Controlled by BMS mode, the dap4 will start and operate the fan at the constant
speed set in CW Speed menu until it receives a new valid fan speed (30% - 100%) from a
BMS. The constant speed is controlled by outputting a constant voltage to the fan speed con-
troller.
The fan speed will automatically increase to the maximum fan speed set in MODULATE MAX
menu when reheat or humidification is required. The fan speed will revert to the BMS con-
trolled fan speed setting when the unit stops calling for reheat or humidification.
WARNING: IF CUSTOMER DECIDES TO USE THIS FAN SPEED CONTROL MODE (FAN
SPEED CONTROLLED BY BMS), DATA AIRE WILL NOT BE RESPONSIBLE FOR ANY EF-
FECTS, MALFUNCTIONS OR SPACE CONTROL CONDITIONS CAUSED BY THIS
SELECTION.
3. Speed Proportional to CW Valve (Vlv. Pos. Speed)
On units where proportional fan speed control based on the CW valve position is required, the
maximum fan speed is programmed in MODULATE MAX menu, and the minimum fan speed
as a percentage of the maximum fan speed is programmed via MODULATE MIN speed menu.
EXAMPLE: Assume a fan with a speed capacity of 1750 RPM, a maximum design fan speed of
1501 RPM and a minimum design fan speed of 901 RPM. Menu Modulate Max would be set
to 1501/1750 = 0.8577 or 86%, and menu Modulate Min would be set to 901/1501 = 0.6003 or
60%.
When the fan starts, it will operate at the minimum fan speed. As the chilled water valve opens,
the fan speed will modulate proportionally based on the CW valve position from the minimum
fan speed (when the CW valve is fully closed) to the maximum fan speed (when the CW valve
is fully open).
The fan will operate at the maximum programmed speed when the unit calls for reheat or
humidification.
Water valve action menu (Wtr Vlv Action) can be chosen for reverse acting valves. With this
