VAV Application

A default application for the VAV14-IP controls the airflow adjusting it to a current demand for ventilation intensity depending on:

• occupancy status,

• space temperature,

• setpoint temperature,

• CO₂ level.

The application allows to optimize energy consumption of the air handling units.

The airflow control is based on the currently measured airflow in relation to the calculated setpoint for the airflow, which is calculated based on the demand for cooling, heating, or due to excessive CO₂ concentration, as well as due to forcing from the HVAC mode. The airflow demand is affected by the level of damper opening resulting from the airflow control loop.

The control loop for the CO₂ concentration in the room has a priority effect on the calculated airflow setpoint. This means that the airflow can be higher than the cooling or heating demand if the CO₂ concentration in the room is too high in order to ventilate the room. In the absence of a CO₂ sensor, the control loop does not affect the calculated flow setpoint.

The supply air temperature control loop is used to limit the supply air temperature specified by the current supply air setpoint based on the supply air temperature measurement. It can limit the reheater or perimeter control. The supply air temperature control loop operates only when there is a heating demand. If there is no supply air sensor, the control loop has no effect on limiting the supply air temperature.

The application is constructed to work in the following device configurations:

• VAV cooling only,

• VAV cooling/heating,

• VAV cooling with a water reheater and optional perimeter,

• VAV cooling with a 2-stage electric reheater and optional perimeter,

• series fan powered VAV cooling with a water reheater and optional perimeter,

• series fan powered VAV cooling with a 2-stage electric reheater and optional perimeter,

• parallel fan powered VAV cooling with a water reheater and optional perimeter,

• parallel fan powered VAV cooling with a 2-stage electric reheater and optional perimeter.

Configuration Scope

The VAV default application can be configured in the following areas:

• device type,

• damper direction,

• heating device type and priority,

• fan type,

• occupancy source, window and presence sensors,

• temperature source,

• temperature setpoint and offset,

• CO₂ source,

• airflow loop settings.

Application Modes

Taking into consideration all configuration options, types of devices used, and airflow settings, the VAV default application can be adapted to work in the following modes:

• VAV cooling only,

• VAV cooling/heating,

• VAV with water reheater and optional perimeter,

• VAV with up to 2-stage electric reheater and optional perimeter

• series fan powered VAV cooling with water reheater and optional perimeter,

• series fan powered VAV cooling with up to 2-stage electric reheater and optional perimeter,

• parallel fan powered VAV cooling with water reheater and optional perimeter,

• parallel fan powered VAV cooling with up to 2-stage electric reheater and optional perimeter.