2800 LAURA LANE
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MIDDLETON, WI 53562
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FAX (608) 836-9044
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www.tcs-basys.com
12
The software allows you to override the thermostat by putting
the override parameter into the remote mode, and thus dis-
abling the timed override.
SETBACK AND OVERRIDE APPLICATIONS
In most applications, it is desired to maintain a regular sched-
ule, 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 external time
clock and close the contact when you want the room occu-
pied, such as with a switch or wind-up timer. If each occupan-
cy period is about the same, (theaters, meetings) another
option is to set the DI3 to external time clock, and use the
timed override button to put the unit in occupied mode.
To make the unit always occupied, set DI3 to external time
clock and short the DI3 terminal to ground.
DISCHARGE AIR TEMPERATURE SENSING
The SZ1017a, SZ1041, SZ1051 and SZ1053 accept a remote
discharge air sensor for monitoring purposes. (See setup
instructions for dipswitch placement for this option.)
SZ1041 and SZ1051
Choose YES in programming screen #30b (for the SZ1041) or
#29a (for the SZ1051) only if you have a discharge air sensor
installed and you want the SZ1041 or SZ1051 to use its built-
in economizer functions. If NO is chosen, the discharge air is
still monitored. You must also have an outdoor air sensor
installed for economizer operation. See Economizer Operation
section for further programming options.
SZ1017a and SZ1053
Choose YES in programming screen #29d (for the SZ1017a)
or #33c (for the SZ1053) 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 monitored.
When this function is enabled, a LOW LIMIT and HIGH
LIMIT are entered in steps #30d and #31d (SZ1017a) or #34c
and #35c (SZ1053). If the HIGH LIMIT is reached, the fan and
heating devices 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 devices will be turned
off and will remain off until the discharge air temperature rises
3° above that limit. When either limit is reached, the service
LED will be on until normal operation resumes.
The discharge air span is 0 to 150°F (-17.8 to 65.6°C).
ANALOG OUTPUTS (SZ1041, SZ1051)
On the SZ1041, analog output one is used to control an econ-
omizer. On the SZ1051, analog output one is used to control
the heating or cooling in a space, while analog output two is
used to control an economizer.
ANALOG OUTPUTS/DISCHARGE AIR RESET
(SZ1017a, SZ1053)
The analog output on the SZ1017a is used to control the heat-
ing or cooling in a space. The analog outputs on the SZ1053
are used to control the heating and cooling in a space. To use
the discharge air reset function, a discharge air sensor must be
installed. In programming step #29d (for the SZ1017a) or #33c
(for the SZ1053), the discharge air sensor must be enabled. In
programming step #32d (SZ1017a), or #36c and/or #37c
(SZ1053), the control must be based on DISCHARGE air.
In programming screen #33d (SZ1017a), or #38c and/or #39c
(SZ1053), you are asked to enter a discharge air setpoint. The
discharge air temperature will be controlled to this setting by
modulating the heating or cooling device.
In programming screen #34d (SZ1017a), or #40c and/or #41c
(SZ1053), you are asked to enter a reset ratio factor. This is
the number of degrees that the discharge air setpoint is raised
when the room temperature falls below the heating setpoint by
1 degree if the analog output is set for heating, or the number
of degrees that the discharge air setpoint is lowered when the
room temperature rises above the cooling setpoint by 1 degree
if the analog output is set for cooling.
OUTDOOR AIR TEMPERATURE SENSING
The SZ1017a, SZ1041, SZ1051 and SZ1053 accepts a remote
outdoor temperature sensor for monitoring purposes. (See
setup instructions for dipswitch placement for this option.)
Choose YES in programming screen #35d (for the SZ1017a) or
#27b (SZ1041) or #37a (SZ1051) or #42c (SZ1053) only if
you are using an outdoor air sensor and you want to enable the
outdoor air heating and cooling lockout functions. If NO is
chosen, the outdoor air is still monitored.
When the function is enabled, COOLING LOCKOUT TEMP
and HEATING LOCKOUT TEMP are entered in steps #36d
and #37d (for the SZ1017a) or #28b and #29b (SZ1041) or
#38a and #39a ( SZ1051) or #43c and #44c ( SZ1053). If the
outdoor air temperature falls below the COOLING LOCKOUT
TEMP, all cooling stages will be locked out and will remain
locked out until the outdoor air temperature rises 2° above the
lockout temperature. If the outdoor air temperature rises above
the HEATING LOCKOUT TEMP, all heating stages will be
locked out and will remain locked out until the outdoor air
temperature falls 2° below the lockout temperature.
The outdoor air span is -40 to 160 °F (-40.0 to 71.1 °C).
FAN PROVING
The SZ1017a, SZ1041, SZ1051 and SZ1053 allow DI1 to be
set for fan proving to protect equipment on fan failure. To uti-
lize this, a pressure or current switch is required, which indi-
cates when the fan is running. If the thermostat turns on the
FAN, and DI1 is not closed after thirty seconds, the system
will go to OFF, disabling all outputs, the fan LED will turn off
and the service LED will be lit until the system is manually
reset by switching the system to a mode other than OFF.
