Application

Application Notes
Dual Duct Sequence Configurations
6
Siemens Industry, Inc.
Application Note
A6V11692055
Smart Infrastructure – Building Products
2019-04-01
Overview
14269
Dual Duct Variable Volume with Two Inlet Sensors, 2-Stage Electric Heat, Chilled Ceiling
and Hot Water Radiator: Template 14269 (on DXR2.x18).
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 1
ST
, 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.
Plant Diagram
VavSuPos1
VavSuPos2
Variable air volume supply air
damper
TSu
Supply air temperature sensor
(for monitoring and diagnostics)
VavSuDiffP1
VavSuDiffP2
Supply air VAV differential
pressure sensor
TR
Room temperature
(part of ROpUn)
HclEl
Electric heat coils (2-stage)
ROpUn
Room operating unit
Rad
Modulating HW radiator
Description of Functions
Basic Functions
Auxiliary Functions
⚫ Operating modes for room, plant and
devices
⚫ Each VAV duct can provide conditioned
air for cooling or heating
⚫ Ventilation air provided by either or both
ducts
⚫ Mixing control or snap action control,
configurable
⚫ Supply air VAV box, pressure sensor
⚫ Electric heat coils (2-stage)
⚫ Hot water radiator
⚫ Supply chain coordination
⚫ Green Leaf function
⚫ Comfort button for occupant override