Application

Application Notes
Dual Duct Sequence Configurations
21
Siemens Industry, Inc.
Application Note
A6V11692042
Smart Infrastructure – Building Products
2019-04-01
Use Case 5a – Constant volume DD option, ventilation in both ducts, mixing control, with cold
duct ventilation in deadband
VntSprtDdband = Duct 1, example 1:
Cold duct stays at constant max volume
during cooling and deadband to provide the
elevated minimum ventilation setting.
At the heating setpoint, mixing control
occurs to maintain constant volume dual
duct air flow and room temperature control:
as heating load ramps up, hot duct damper
modulates open and cold duct damper mod-
ulates down.
Optional heat elements (e.g. hot water coil)
can be configured to provide additional
heating after the hot duct has reached max-
imum flow.
VntSprtDdband = Duct 1, example 2:
Cold duct stays at constant max volume
during cooling and deadband with an addi-
tional level of supplemental ventilation air
flow provided by hot duct. The air flows are
summed to provide an elevated minimum
ventilation setting larger than max cooling
flow.
At the heating setpoint, mixing control
occurs to maintain constant volume dual
duct air flow and room temperature control:
as heating load ramps up, hot duct damper
modulates open and cold duct damper mod-
ulates down. When the total flow (ventila-
tion setpoint) is larger than the max heating
setpoint, the cold duct provides the addi-
tional supplemental ventilation air flow.
Optional heat elements (e.g. hot water coil)
can be configured to provide additional
heating after the hot duct has reached max-
imum flow.