VAVFanControl
Applicable to OS V1.7
The VAVFanControl component allows to control the fan speed (if configured - both analog and digital depending on the fan type), occupancy status, and the demand for heating or cooling. The component determines the effective setpoint for regulating the fan speed, based on the output from the temperature control loop (only for heating in parallel fan case), the setpoints for minimum and maximum fan speed, and the current occupancy status and operating mode (normal, balancing). Additionally, it is possible to use the fan in a selected HVAC mode - such as WarmUp.
VAVFanControl slots
The VAVFanControl component has the following slots:
Status: informs about the status of the component; if the Fan Type/Fan Commend/Occupancy Status/HVAC Mode slot or one of the demand input slots has a null value then the status is fault, otherwise it is OK;
Available statues: OK, Fault, Disabled, Unlicensed, Down, Error;
Fan Analog Speed: returns an analog fan speed resulting from the connected control loops;
Fan Digital Command: returns a calculated digital fan command;
Note
Fan control is calculated in the component based on the fan control mode, type, HVAC mode, occupancy, and active control loops. Fan analog speed also takes into account Max Fan Speed and Min Speed Values, which can limit the range of the fan operation.
Fan Type: specifies a fan type (series or parallel; version without a fan is None);
Fan Command: allows to set a test fan control, if configured in Fan Type for use;
Available settings: Auto, Max Speed, Min Speed, Stop;
Control Mode: specifies a control mode for the fan in the analog mode:
Available settings:
Analog (linearly according to the heating/cooling demand and within limit speeds set in the MinFanSpeed and MaxFanSpeed components),
Digital (on/off binary mode available in occupied, bypass and, optionally, standby statuses);
Hvac Mode: receives the HVAC mode set in the HVACMode variable;
Available settings: Auto, Heat, Cool, MorningWarmUp, PreCool, NightPurge, Fire, Off;
HVAC modes
Auto:
parallel fan: working on heating demand,
series fan: working if occupied/bypass or standby (if allowed);
Heat:
parallel fan: working on heating demand,
series fan: working only on heating demand if occupied/bypass or standby (if allowed);
Cool:
parallel fan: inactive,
series fan: working only on cooling demand if occupied/bypass or standby (if allowed);
MorningWarmUp:
parallel fan: if the WarmUpParallelFan variable is set to true, the parallel fan is active in this mode,
series fan: ventilator set to the maximum speed;
PreCool:
parallel fan: inactive,
series fan: ventilator set to the maximum speed;
NightPurge:
parallel fan: inactive,
series fan: ventilator set to the maximum speed;
Off: both types of fan disabled;
Fire:
parallel fan: inactive,
series fan: set to the maximum speed.
Occupancy Status: specifies an occupancy status resulting from the values of window contact, present motion, network occupancy, schedule occupancy, airflow detection, and panel button override;
Available settings: Occupied, Unoccupied; Standby, Bypass;
Cool Demand: receives the value from the connected cooling PID loop;
Heat Demand: receives the value from the connected heating PID loop;
Max Fan Speed: allows to set a maximum fan speed - high limit for the range of the fan operation;
Min Fan Speed: allows to set a minimum fan speed - low limit for the range of the fan operation;
Warm Up Parallel Fan: allows to run a parallel fan in the MorningWarmUp HVAC mode;
Standby Series Fan: allows to run a series fan in a standby occupancy mode;
Fan Delay Off: allows to set a delay fan off time after heat demand goes to 0%.
Note
In systems with a water reheater the Fan Delay Off may be set to 0. However, setting the delay is required in systems with an electric reheater.
VAVFanControl in the application