32 TRG-TRC014-EN
notes
period two
Components of a VAV System
Similar to electronic control, an electronic pressure transducer enables
pressure-independent control of the VAV terminal unit. The digital controller
positions the modulation device and operates the fan and the heat source.
Minimum and maximum airflow settings are adjusted through a
communication link to the digital controller. A 24-volt power supply is required
to power the unit actuator and controls.
Direct Digital Control (DDC)
▲ Electronic pressure transducer provides
pressure-independent control
▲ Digital controller positions modulation device,
controls terminal fan and heat source
▲ Minimum and maximum airflow settings
adjusted through communication link
▲ Electric power supply operates modulation
device and electronic controller
Figure 47
