Empirical models of airflow output and power consumption were developed for series fan powered variable air volume terminal units at typical operating pressures. Terminal units with 8 in. (203 mm) and 12 in. (304 mm) primary air inlets from three different manufacturers were evaluated. Generalized models were developed from the experimental data with coefficients varying by size and manufacturer.

Fan power and airflow data were collected at downstream static pressures of 0.25 w.g. (63 Pa). Upstream static pressures ranged from 0.1 to 2.0 in w.g. (25 to 498 Pa). Data were collected at four different primary air damper positions and at four terminal unit fan speeds. Model variables included the RMS voltage entering the terminal unit fan, the inlet air differential sensor pressure, and the upstream static pressure.

In all but one of the VAV terminal units, the resulting models of airflow and power had R2 values greater than 0.98. For the remaining unit, a faulty motor had been installed and shipped in the unit which prevented proper operation of the SCR. These models can be applied to HVAC simulation programs to model series fan powered VAV systems.

Units: Dual