Vav Box Control Logic

The sup ply airflow setpoint is reset from the zone maximum airflow setpoint when the space is at full cooling proportion ally down the zone minimum when no cooling is required.

Vav box control logic. Conventional vav box logic. In many cases a variable air volume box is nothing but an assembly of a sheet metal box with a damper and controls inside a control panel. Vav box control logic. A vav box is integral to the ductwork connecting primary ductwork to secondary ductwork.

Summarizes a detailed analysis of vav box control and selection1 and provides vav boxes sizing criteria that will mini mize lcc in typical applications. A variable air volume vav box is a part of an hvac system in commercial buildings. 6 vav terminal control applications application note pressure independent an improved vav box control strategy employs cascaded proportional integral control loops. The zone temperature loop samples space temperature and resets the airflow setpoint between the minimum and maximum flow settings.

Dual maximum vav box logic summary title 24 requires dual maximum logic for vav zones with ddc setpoints set minimum and heating maximum setpoints as low as possible minimum allowed by controls is seldom a factor if box properly sized do not use maximum allowed by t 24 just because it is legal cost impact. If the fan airflow is higher than the pre set critical value 70 of the design flow the fan speed is proportionally adjusted based on the airflow ratio. Vav controls and airflow setpoints figure 1 shows a single duct vav box using pressure independent control logic. Vav boxes with reheat coils were traditionally controlled using the con trol logic shown in.