Siemens 125-1957 User Manual
6
Siemens Building Technologies,Inc.
2
Applications
Basic Operation
The Unit Vent Controller
⎯0 to 10V Output provides Direct Digital Control (DDC) technology
for unit ventilator applications. The applications available in this controller are as follows:
•
Heating and/or Chilled Water Cooling,
ASHRAE Cycles l and II
ASHRAE Cycles l and II
Application 2281
•
Heating and/or Chilled Water Cooling,
ASHRAE Cycle III
ASHRAE Cycle III
Application 2283
•
Heating and DX Cooling,
ASHRAE Cycles I and II
ASHRAE Cycles I and II
Application 2284
•
Heating and DX Cooling,
ASHRAE Cycle III
ASHRAE Cycle III
Application 2286
•
Nesbitt Cycle W
Application 2287
•
Slave Mode (no control; available for set up,
and point extension device)
and point extension device)
Application 2299
Control Temperature Setpoints
The controller maintains a specified temperature setpoint based on Day/Night mode, the
heating/cooling mode, or the setpoint dial (if used).
heating/cooling mode, or the setpoint dial (if used).
Day/Night Mode
The controller maintains the specified day setpoint temperature during daytime hours and the
specified night setpoint at night.
specified night setpoint at night.
Day Heating Operation
The controller maintains the room temperature by resetting the unit ventilator's discharge
temperature setpoint (2281/2284), modulating the available coil control device, controlling
auxiliary radiation (if provided), positioning the outdoor air or face-bypass damper.
temperature setpoint (2281/2284), modulating the available coil control device, controlling
auxiliary radiation (if provided), positioning the outdoor air or face-bypass damper.