Application

Application Notes
Sequence of Operation – Summary
25
Siemens Industry, Inc.
Application Note
A6V11692055
Smart Infrastructure – Building Products
2019-04-01
Sequence of Operation – Summary
Overview
This application modulates the supply air dampers of the dual duct terminal box for
cooling, heating, and ventilation. Terminal box airflow is maintained at the larger of
ventilation airflow or the heating or cooling airflows.
A chilled ceiling device is active during cooling. When in heating, the 2-stage
electric heating coils sequence with the hot duct supply damper to maintain room
temperature at setpoint.
The analog outputs for damper control (1DMPR POS, 2DMPR POS) are modulated
by respective airflow PID controllers. Two binary outputs activate the stages of
electric heat (HTG EL 1ST, HTG EL 2ST). Additionally, a modulating output
commands the hot water radiator (RAD V POS) and a modulating AO commands
the chilled ceiling device (PANL C POS10).
Each duct can be configured to provide hot, cold (or both) airflow, and the source
for ventilation air can be configured to come from cold duct, hot duct, or both.
Additionally, the transition between heating and cooling is configurable for hot/cold
airflow mixing control or snap acting control. See Dual Duct Configurations for
detailed information on these topics.
PID controllers are provided for each of the following control elements:
⚫ Room heating demand
⚫ Room cooling demand
⚫ VAV duct 1 airflow setpoint
⚫ VAV duct 2 airflow setpoint
⚫ Ventilation demand
(basic ventilation and/or demand control)
Inputs
⚫ Room temperature sensor
⚫ Room temperature setpoint shift
⚫ Temporary Comfort button
⚫ GreenLeaf button
⚫ Differential pressure sensor, Duct 1
⚫ Differential pressure sensor, Duct 2
⚫ Supply air temperature sensor
⚫ Condensate monitor
⚫ Heating coil overtemperature detector
Outputs
⚫ Supply damper actuator, duct 1
⚫ Supply damper actuator, duct 2
⚫ Binary output for stage 1 electric heat
⚫ Binary output for stage 2 electric heat
⚫ Hot water radiator coil modulating valve
⚫ Chilled ceiling modulating valve