R
2800 LAURA LANE • MIDDLETON, WI 53562 • (800) 288-9383 • FAX (608) 836-9044 • www.tcsbasys.com
8
SETBACK AND OVERRIDE APPLICATIONS
In most applications, it is desired to maintain a regular
schedule, and allow timed override with the button on
the face or with a remote momentary contact.
To allow a regular schedule, and also automatically
override with the use of occupancy or light sensor,
set DI3 to override and set it up so that the contact is
closed when you want the override.
For applications where a room might not be used on a
regular schedule, such as conference rooms, set DI3
to time clock and close the contact when you want the
room occupied, such as with a switch or wind-up timer.
If each occupancy period is about the same, (theaters,
meetings) another option is to set the DI3 to time
clock, and use the timed override button to put the unit
in occupied mode.
To make the unit always occupied, set DI3 to time
clock and short the DI3 terminal to ground.
DISCHARGE AIR TEMPERATURE SENSING
The SZ1018 accept a remote 1000
Ω
discharge air
sensor (TS1009 or TS1002) for monitoring purposes.
(See setup instructions for dipswitch placement for this
option.)
Choose YES in programming screen #39 only if you
are using a discharge air sensor and you want to
enable the discharge air temperature high and low
limit functions or discharge air reset function. See
Discharge Air Reset section for further programming
options. If NO is chosen, the discharge air is still moni-
tored.
When the function is enabled, a LOW LIMIT and HIGH
LIMIT are entered in steps #40 and #41. If the HIGH
LIMIT is reached, the fan and heating stages will be
turned off and will remain off until the discharge air
temperature falls 3° below that limit. If the LOW LIMIT
is reached, the fan and cooling stages will be turned
off and will remain off until the discharge air rises 3°
above that limit. When either limit is reached, the ser-
vice LED will be on until normal operation resumes.
The SZ1018 can use a remote discharge temperature
sensor for changeover from heating to cooling based
on the ANALOG SETPOINT set in step #25.
The discharge air span is 0 to 150 °F (-17.8 to 65.6
°C).
ANALOG OUTPUT / DISCHARGE AIR RESET
The analog output on the SZ1018 are used to control
the heating or cooling in a space. To use the discharge
air reset function, a discharge air sensor must be
installed. In programming step #30, the discharge air
sensor must be enabled. In programming step #42,
the control must be based on DISCHARGE air.
(Do not use with Zoning System)
In programming screen #43, you are asked to enter
a discharge air setpoint. The discharge air tempera-
ture will be controlled to this setting by modulating the
heating or cooling device.
Operation
UNOCCUPIED SETBACK
The SZ1018 operate in either an occupied or unoc-
cupied mode. During the occupied mode, the occupied
heating and cooling setpoints will be maintained, and
the fan will operate according to its occupied setting.
During the unoccupied mode, the unoccupied heating
and cooling setpoints will be maintained, and the fan
will operate according to its unoccupied setting. The
occupied LED will be lit when the unit is operating in
the occupied mode.
The occupied schedule may be set utilizing the inter-
nal time clock or DI3 may be used with an external
time clock, whereas when DI3 is closed, the unit is in
the occupied mode. The Smart Recovery function is
disabled when DI3 is used for external time clock.
OVERRIDE
A timed override is available using the button on the
face of the thermostat or through momentary contacts
wired into the OVR terminal. The amount of time the
unit will be overridden is set from 0 to 255 minutes in
the programming screen. This override behaves differ-
ently depending on the mode the thermostat is operat-
ing in (occupied or unoccupied) and the options that
have been enabled within the software.
In standard mode, the override only activates in unoc-
cupied mode and takes the thermostat into occupied
mode. If "Override for Occupied Period" is enabled
using the software, the override also activates in occu-
pied mode and takes the thermostat into unoccupied
mode. In either case, you are able to view the time
remaining in the override period both within the soft-
ware and by using the service button to scroll through
the status screens. If the occupant desires to return
the thermostat to unoccupied or occupied operation
(depending on how the override was used) before the
override time remaining elapses, they may press the
override button again.
Additionally, an "Override Hold" feature is built into the
thermostats. When in unoccupied mode, pressing the
override once and then pressing/holding it for 5 sec-
onds puts the thermostat into a "hold” mode (the over-
ride LED on the thermostat will flash quickly to confirm
the mode change). In this mode, the override setpoints
are used until the next occupied period is reached or
until the thermostat is manually taken out of the "hold"
mode by pressing the override button again. This
feature also works when the "Override for Occupied
Period" is enabled BUT starting from the occupied
mode and holding the thermostat in the unoccupied
state.
A continuous override is available through the DI3
contact or the software. If DI3 is set to external over-
ride, the unit will be in the occupied mode whenever
the DI3 contact is closed. When using this option, the
timed override may still be activated.
