5012886-YIM-B-0517
Johnson Controls Unitary Products
25
Pin Temperature sensor connections at right on upper edge of UCB
SAT+
Supply Air Temperature sensor input from 10K
Ω
@ 77
°
F, Type III negative temperature coefficient
thermistor
Input required for operation; 3.625 VDC reading SAT+ to SAT
–
with open circuit. Used in heat/cool staging cutouts, free cooling
operation, demand ventilation operation, comfort ventilation
operation, economizer loading operation, VAV cooling
operation, hydronic heat operation.
RAT+
Return Air Temperature sensor input from 10K
Ω
@ 77°F, Type III negative temperature coefficient
thermistor
Input required for operation; 3.625 VDC reading RAT+ to RAT
–
with open circuit. Used in return air enthalpy calculation.
Substitutes for space temperature if no other space
temperature input is present.
OAT+
Outside Air Temperature sensor input from 10K
Ω
@ 77°F, Type III negative temperature coefficient
thermistor
Input required for operation but may be a communicated value;
3.625 VDC reading OAT+ to OAT
–
with open circuit. Used in
heat/cool cutouts, low ambient cooling determination, dry bulb
free cooling changeover, outside air enthalpy calculation,
economizer loading operation, heat pump demand defrost
calculation.
CC1+
#1 refrigerant circuit Condenser Coil temperature
sensor input from 10K
Ω
@ 77°F, Type III negative
temperature coefficient thermistor
Input required for heat pump units, not required for A/C units;
3.625 VDC reading CC1+ to
CC1
–
with open circuit. Used in heat pump demand defrost
calculation.
EC1+
#1 refrigerant circuit Evaporator Coil temperature
sensor input from 10K
Ω
@ 77°F, Type III negative
temperature coefficient thermistor
Input required for operation; 3.625 VDC reading EC1+ to EC1
–
with open circuit. Used in suction line temperature safety.
CC2+
#2 refrigerant circuit Condenser Coil temperature
sensor input from 10K
Ω
@ 77°F, Type III negative
temperature coefficient thermistor
Input required for 2-compressor heat pump units, not required
for 2-compressor A/C units, not active for 1-compressor units;
3.625 VDC reading CC2+ to CC2
–
with open circuit. Used in
heat pump demand defrost calculation.
EC2+
#2 refrigerant circuit Evaporator Coil temperature
sensor input from 10K
Ω
@ 77°F, Type III negative
temperature coefficient thermistor
Input required for operation of 2-compressor units, not active for
1-compressor units; 3.625 VDC reading EC2+ to EC2
–
with
open circuit. Used in suction line temperature safety.
Pinned connections on right edge of UCB
RAH+
Return Air Humidity input from 0-10 VDC @ 0-
100% RH sensor
Input required for reheat units, optional in all other units, may be
a communicated value. Used in return air enthalpy calculation,
temperature/humidity setpoint reset, reheat operation.
DCT PRS+
Supply Duct Pressure input from 0-10 VDC @ 0-
5” w.c. sensor
Input required for variable air volume units. Used in VAV indoor
blower operation.
DFS (upper pin)
24 VAC hot return from Dirty Filter Switch
Optional input; switch closure for greater than 15 seconds
during indoor blower operation
initiates a notification alarm
DFS (lower pin)
24 VAC hot out for Dirty Filter Switch
Connects through circuit trace to the R terminal
APS (up-
per pin)
24 VAC hot return from Air Proving Switch
When this optional input is enabled: the air proving switch must
close within 30 seconds
of initiation of indoor blower operation and not open for greater
than 10 seconds during in- door blower operation to allow heat/
cool operation and prevent an “APS open” alarm; the air proving
switch must open within 30 seconds of termination of indoor
blower operation to prevent an “APS stuck closed” notification
alarm
APS (lower pin)
24 VAC hot out for Air Proving Switch
Connects through circuit trace to the R terminal
C
Common for the VFD output
Negative of the VDC circuit for the VFD output
Table 9:
Smart Equipment™ UCB Details (Continued)
Description
Function & Comments
