Application

Application Notes
Dual Duct Sequence Configurations
14
Siemens Industry, Inc.
Application Note
A6V11692042
Smart Infrastructure – Building Products
2019-04-01
rent value of ventilation flow demand, provided that the ventilation flow demand is greater than cold duct air
flow, otherwise hot duct air flow will be zero.
Use Case 2c – VAV DD with ventilation in both ducts, last duct ventilation in deadband, with
mixing control:
Last active duct will stay open in deadband
to meet a ventilation requirement. Outside
of deadband, as the heating load (or the
cooling load) ramps up, the ducts provide a
hot/cold mixture to meet the ventilation
requirement. See additional information
below.
Ducts may close if ventilation requirement
goes to zero.
Parameter configuration for use case 2c:
• VavSuChovrCnd1 = Cooling
• VavSuChovrCnd2 = Heating
• VntDuctSprt = Both ducts
• CtlStrgy = Mixing control
• VntSprtDdband = Last duct
In use case 2c, with the thermal load in deadband the air flow from the last active duct (heating or cooling) will
equal the current value of the ventilation flow demand (may vary per room operating mode or DCV); the inac-
tive duct air flow will be zero.
If the last active duct = cold duct, then when the system exits the temperature deadband the behavior is as
follows:
• Exiting deadband on a call for cool when last duct is the cold duct and CtlStrgy = Mixing control;
On an increase in cooling load, the cooling flow demand on the cold duct modulates from cooling flow min