Basic Documentation
26 / 44
Siemens VAV compact controller G..B181.1E/3 | VAV modular controller ASV181.1E/3 CE1P3544en
Smart Infrastructure 2021-10-26
5.2.1 Calculation formulas
The parameters are based on the following formulas:
300 Pa is the upper limit of the operating range of the differential pressure sensor.
The nominal pressure is the differential pressure in the VAV box at a given nominal
volume flow, determined by the OEM specification.
5.2.2 Conversion of C-values into Vn values
In case the C-value of a VAV box is known, it can be converted into a
corresponding Vn value as both are linked by Δpnom
.
and
Example for a box with C = 57.2 and Vnom = 900 m3/h:
In this case, set Vn = 1.1 which corresponds to a Δpnom = 248 Pa.
Calculation of Vn
(Δpnom = nominal
pressure)
Min. and max. volume
flows (Vmin / Vmax)
Actual relative flow as
function of setpoint and
min. / max. limits
Actual relative flow as
function of differential
pressure
Actual differential
pressure as function of
actual flow
Formulas are linked by
Δpnom