Application

Sequence of Operation
Application Notes
41
Siemens Industry, Inc.
Application Note, App 2928
140-1302
2015-07-07
Application Notes
Supply Only - Operating Without a General Exhaust Box
This application can operate without a general exhaust box. If a general exhaust box is
not being controlled, set TRACK METHOD to FLOW and set the following points:
 TRACK MODE to 3.
– Without a fume hood attached, use a value of 3 = ETS (exhaust tracks supply)
Flow Tracking, should be used for both the occupied and unoccupied modes.
– With a fume hood attached, use a value of 0 = STE (supply tracks exhaust)
Flow Tracking, should be used for both the occupied and unoccupied modes.
 GEX FLO COEF to 0.
When GEX FLO COEF equals 0, GEX AIR VOL will always read 0, but will never
display as Failed.
 OCC GEX MIN and UOC GEX MIN to 0.
If these two points are not set to 0, GEX AIR VOL— will read 0 since GEX FLO
COEF was set to 0—will be less than the general exhaust box minimum, resulting
in a false ventilation alarm.
 OCC GEX MAX and UOC GEX MAX left at default or a higher value.
These two points should be set to the highest value: 1) default or 2) OCC SUP
MAX / UOC SUP MAX – small values will result in the supply box not being able to
reach higher flow setpoints.
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.
General Exhaust Only - Operating Without a Supply Box
BTU compensation in Application 2928 will not function without supply airflow. Use
Application 2922.
Wiring Diagrams
Offboard Air Module Wiring.
CAUTION
The LCM-OAVS has two terminal blocks with terminations numbered identically
(terminations 1 through 16). DO NOT mix these up with each other.
If the LCM-OAVS is not connected as shown, it is not resistant to electrical surges. It
is also susceptible to interference from other equipment.