Application

Room Segment Functions
Device Control Functions HVAC
56
Siemens Industry, Inc.
Application Note
A6V11692055
Smart Infrastructure – Building Products
2019-04-01
Description
Parameter
Pre-loaded Value
Hysteresis for air volume flow state (1 and 2)
HysAirFlSta
2%
Enable monitoring for fan state → Must = 0:No for parallel fan
powered box applications; must = 1:Yes for series fan powered box
applications.
EnMonFanSta
No
Enable monitoring for missing air volume flow
0:No
1:Yes
EnMonNoAirFl
Yes
Minimum Ventilation Flow
In all installations (with or without demand control ventilation DCV), the Room
ventilation function provides minimum primary airflow when configured ventilation
is required. This can be set and enabled per operating mode. This provides
additional flexibility and energy savings and effectively replaces the VAV minimum
cooling and heating supply airflow setpoints. During heating (or cooling) when a
minimum heating (or cooling) flow setpoint is configured, the larger value
compared to ventilation will be used.
NOTE:
VAV and FPB have the minimum room air volume flow for the room operating
modes configured and enabled in the VAV Ventilation Control application
function, as follows:
- Minimum room air volume flow for comfort – 150 CFM
- Min. room air volume flow for pre-comfort – 150 CFM
- Minimum room air volume flow for economy – 0 CFM
- Min. room air volume flow for protection – 0 CFM
The minimum ventilation setting provides a low limit to the terminal box minimum
ventilation parameter (VavSuAflMinVnt), preventing minimum ventilation from
going below 150 CFM. For more information, see Airflow Sequencing and
Airflow Limits (found under Air Volume Flow Setpoint Calculation section).
Nominal Air Volume Flow
Nominal air volume flow refers to the "nominal" flow rating of the terminal box, the
maximum flow for which it is rated.
Default value of AirFlNom
⚫ Standard preloaded VAV / FPB templates: AirFlNom default = 1200 ft3/min
⚫ Raw factory value in unconfigured VAV or FPB type: AirFlNom default = 100
m3/h (59 ft3/min)
⚫ Lab (CET) type: see Lab documentation
(Dual Duct standard preloaded templates)
AirFlNom is used to define the scaling value that converts physical flow values to
their relative (percent) flow values. When AirFlNom is used, all of the application’s
air volume flow percent calculations are based on the value of AirFlNom. This
means that the value of AirFlNom - when used - is crucial for the proper
functioning of the automation station’s air volume flow control algorithms.
Dual Duct applications have the option of setting AirFlNom to zero, in which case it
is not used. See the following guidelines for specific information.