Compact, static

Functiebeschrijving

VAV terminal units control the volume flow in a closed loop, i.e. measurement – comparison – control.

The volume flow rate is determined by measuring the differential pressure (effective pressure). For this purpose the VAV terminal unit is fitted with a differential pressure sensor.

The integral differential pressure transducer transforms the effective pressure into a voltage signal, which is then analysed by the microprocessor of the controller. The volume flow rate actual value is available as a data point or voltage signal. The factory setting is such that a 10 V DC voltage signal always corresponds to the nominal volume flow rate (Vnom).

The volume flow rate setpoint value comes from a higher-level controller (e.g. room temperature controller, air quality controller, central BMS), either as a voltage signal or as a data point, or from local switch contacts. Variable volume flow control results in a value between Vmin and Vmax. It is possible to override the room temperature control, e.g. by a complete shut-off of the duct.

The controller compares the volume flow rate setpoint value to the actual value and controls the integral actuator accordingly.

Volume flow rate parameters and voltage ranges are factory stored in the controller. Changes on the customer's site can easily be carried out using an adjustment device, a notebook with service tool, or a bus interface.

Volume flow control

• The volume flow controller works independent of the duct pressure
• Differential pressure fluctuations do not result in permanent volume flow rate changes
• To prevent the control from becoming unstable, a dead band is allowed within which the damper blade does not move.

Any attachments are to be defined with the order code of the VAV terminal unit.

Compact controllers for VAV terminal units

① TVR, TVJ, TVT, TZ-Silenzio, TA-Silenzio, TVZ, TVA, TVRK