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84 SCXG-SVX01B-EN
Control Sequences of
Operation
Occupied/Unoccupied Switching
There are four ways to switch occupied/
unoccupied:
(1) Night setback zone sensor
(2) Field-supplied contact closure
(hardwired binary input to RTM)
(3) Tracer Summit
(4) Factory-mounted time clock
Field Supplied Occupied/Unoccupied
Input on the RTM
This input accepts a field supplied switch
or contacts closure, such as a time clock,
with a rating of 12 mA at 24 VDC
minimum.
Tracer Summit System
The Tracer Summit system can control
the occupied/unoccupied status of the
self-contained unit.
Factory Mounted Time Clock
A time clock can control the
occupied/unoccupied status of the
self-contained unit.
Unoccupied Sequence of
Operation
The unoccupied mode helps conserve
energy during times when a building is
usually unoccupied. When in unoccupied
mode, the unit will control to the
unoccupied setpoints (usually a lower
Figure O-SO-1. Typical cycling morning warmup cycle
sequence of
operation
heating setpoint and higher cooling
setpoint). Setpoints can be programmed
at the HI, Tracer Summit, or the night
setback zone sensor.
The unit enters the unoccupied mode
when the RTM receives a closed signal
on the unoccupied input for more than
five seconds.
For units with supply air temperature
control entering unoccupied mode, the
following sequence will occur:
• Heating/cooling functions cease and the
economizer option closes fully. The
supply fan shuts down for proper cool-
down time of the heat exchanger.
However, the supply fan may remain
on for a short period of time.
• After the supply fan shuts down, the
occupied/unoccupied relay energizes
and the IGV option fully opens. Also, the
VAV box stroke time begins. The VAV
box stroke time is field adjustable to
allow time for VAV boxes to go to the
full open airflow position.
• After the max VAV box stroke time
expires and the IGV’s are fully open, the
supply fan, economizer (if enabled),
compressors, and heat are enabled to
satisfy the unoccupied zone
temperature setpoints.
Note: Unoccupied economizer operation
can be enabled or disabled at the HI or
using Tracer Summit.
Operation