Delta Controls eZFC-424R4-24, Application Manual

Page: 72 / 85

eZFC-424R4-24 Application Guide
Edition 2.6 Page 71 of 84
Demand Control Ventilation
Demand control ventilation (DCV) control sequence determines the amount of fresh air in the
space. The sequence only operates during occupied modes and is disabled when the building is
unoccupied. To use the DCV algorithm, on the Local Inputs tab of the configuration graphic, you
should have a CO2 input (AV3) set up with the DemandVentEnable setting (BV103) turned on.
You should also enter a CO2 demand setpoint in the CO2DemandVentSetpoint (AV185) field.
The CO2 demand is reflected in the demand control ventilation (AV813) object. The algorithm
determines the airflow setpoint needed to meet this demand. The demand increases when the
Space CO2 remains above the CO2DemandVentSetpoint and decreases when the Space CO2
falls below the CO2DemandVentSetpoint.
This airflow setpoint is not only controlled by the CO2 demand, it is also affected by the temperature
control airflow demand via a high select logic. This means a higher CO2 airflow demand could
overheat or overcool a space if that zone does not have any local temperature controls.