Application

Application Notes
Dual Duct Sequence Configurations
23
Siemens Industry, Inc.
Application Note
A6V11692055
Smart Infrastructure – Building Products
2019-04-01
Use Case 5b – Constant volume DD option, ventilation in both ducts, mixing control, and hot
duct ventilation in deadband
VntSprtDdband = Duct 2, example 1:
Hot duct stays at constant max volume
during heating and deadband to provide the
elevated minimum ventilation setting.
At the cooling setpoint, mixing control oc-
curs to maintain constant volume dual duct
air flow and room temperature control: as
cooling load ramps up, cold duct damper
modulates open and hot duct damper modu-
lates down.
Optional cooling elements (e.g. chilled water
coil) can be configured to provide additional
cooling after the cold duct has reached
maximum flow.
VntSprtDdband = Duct 2, example 2:
Hot duct stays at constant max volume
during heating and deadband with an addi-
tional level of supplemental ventilation air
flow provided by cold duct. The air flows are
summed to provide an elevated minimum
ventilation setting larger than max heating
flow.
At the cooling setpoint, mixing control oc-
curs to maintain constant volume dual duct
air flow and room temperature control: as
cooling load ramps up, cold duct damper
modulates open and hot duct damper modu-
lates down. When the total flow (ventilation
setpoint) is larger than the max cooling
setpoint, the hot duct provides the addition-
al supplemental ventilation air flow.
Optional cooling elements (e.g. chilled water
coil) can be configured to provide additional
cooling after the cold duct has reached
maximum flow.