Siemens 125-1957 - Manual (Page 30)

APOGEE Unit Vent Controller
⎯
0 to 10 V Output Owner’s Manual
20 Siemens Building Technologies. Inc.
Application 2287 – Heating and Cooling,
Nesbitt Cycle W
Overview
In Application 2287, the Unit Vent Controller
⎯0-10V Output controls a unit ventilator
equipped with a heating coil, which may be hot water or steam, for Nesbitt Cycle W. Auxiliary
radiation coils are piped parallel to the heating coil and are not controlled separately by the
application. A chilled water coil or a DX cooling coil may be controlled. Heating only units can
also be controlled with this application by overriding HEAT.COOL (Point 5) to HEAT.
Other features available in this application include morning warm-up/cool-down, night mode
override and free cooling.
NOTE: The use of a low temperature detection thermostat (LTDT) is strongly
recommended for hot water and steam systems.
This application controls room temperature by directly modulating the coil control device(s)
and the outdoor air damper according to the schedule defined by Nesbitt Cycle W. The free-
cooling/economizer function is turned on and off by the field panel using FREE CLG (Point
23). The unit ventilator fan is also controlled in this application.
Figure 20. Application 2287 Control Drawing.