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Application

ManualsBrandsSiemens ManualsRoom controlsRoom Condition Monitor, RPM series
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Sequence of Operation
Wiring Diagrams
29
Siemens Industry, Inc.
Application Note, App 2923
The application varies the supply airflow as the fume hood flow changes, in order to
maintain the proper room pressurization. The supply airflow is not varied for cooling
purposes; all temperature control is done by the reheat valve.
Because of this, START should be set to 100 to allow the reheat valve to be controlled
by the full range of TEMP LOOPOUT and to prevent the room temperature PID Loop
from winding up.
General Exhaust Only - Operating Without a Supply Box
This application can operate without a supply box. If a supply box is not being
controlled, set TRACK METHOD to FLOW and set the following points:
TRACK MODE to 0.
A value of 0 = STE (supply tracks exhaust) Flow Tracking, should be used for both
the occupied and unoccupied modes.
SUP FLO COEF to 0.
When SUP FLO COEF equals 0, SUP AIR VOL will always read 0, but will never
display as Failed.
OCC SUP MIN and UOC SUP MIN to 0.
If these two points are not set to 0, SUP AIR VOL— will read 0 since SUP FLO
COEF was set to 0—will be less than the supply box minimum, resulting in a false
ventilation alarm.
OCC SUP MAX and UOC SUP MAX left at default or a higher value.
These two points should be set to the highest value: 1) default or 2) OCC GEX
MAX / UOC GEX MAX – small values will result in the exhaust box not being able
to reach higher flow setpoints.
This setup is useful when the room has a constant source of supply air from other
equipment or sources not connected to the controller. If you enter this constant supply
air volume value into OTHER SUP, the application will vary the general exhaust airflow
as the fume hood flow changes, in order to maintain the proper room pressurization.
Since all temperature control will be done by the reheat valve, START should be set to
100 to allow the reheat valve to be controlled by the full range of TEMP LOOPOUT and
to prevent the room temperature PID Loop from winding up.
Wiring Diagrams
Offboard Air Module Wiring.