Application

Sequence of Operation
Alarms
34
Siemens Industry, Inc.
BACnet LCM-OAVS, Application 6760
140-1326
2015-07-07
Example
CTL STPT = 70°F: OCC.UNOCC = OCC
If
TEMP LOOPOUT =
and
SUP AIR VOL =
then
DISCH STPT =
Formula for DISCH STPT:
CTL STPT +
(TEMP LOOPOUT x
100% ÷ SUP AIR VOL)
10°F
OCC SUP MAX
80°F
70° + (10° x 100% ÷ 100%)
10°F
0.5 ´ OCC SUP MAX
90°F
70° + (10° x 100% ÷ 50%)
–5°F
0.25 ´ OCC SUP MAX
50°F
70° + (–5° x 100% ÷ 25%)
0°F
any flow
70°F
70° + (0° x 100% ÷ x%)
CTL STPT = 70°F: OCC.UNOCC = UNOCC
If
TEMP LOOPOUT =
and
SUP AIR VOL =
then
DISCH STPT =
Formula for DISCH STPT:
CTL STPT +
(TEMP LOOPOUT x
100% ÷ SUP AIR VOL)
10°F
UOC SUP MAX
80°F
70° + (10° x 100% ÷ 100%)
10°F
0.5 ´ UOC SUP MAX
90°F
70° + (10° x 100% ÷ 50%)
–5°F
0.25 ´ UOC SUP MAX
50°F
70° + (–5° x 100% ÷ 25%)
0°F
any flow
70°F
70° + (0° x 100% ÷ x%)
While the actual number of BTUs is not explicitly calculated, DISCH STPT varies as
the supply flow varies in order to maintain a constant quantity of heat entering the
room. (An example of when the supply flow can vary during CV mode is when it varies
in order to maintain proper room pressurization when the fume hood sash position
changes.)
This module also limits TEMP LOOPOUT to values that generate supply air
temperature set points that are less than DISCH MAX and greater than DISCH MIN.
Alarms
The controller is equipped with ventilation and pressurization alarms. It does not
contain temperature alarms. The controller’s alarms are designed to:
 Inform room occupants of hazards.
 Inform building operation personnel that the system is not functioning correctly.
 Supply data for documenting laboratory safety records through trending.
These alarms can be annunciated locally and/or broadcast across a network.