Low-Voltage Connection Points - Bosch SM Series Installation, Operation And Maintenance Manual

12 | Electrical

Low-Voltage Connection Points

Function
24 VAC Common
24 VAC Power
Fan Operation
3
Reversing Valve
st
Compressor 1 Stage
nd
Compressor 2 Stage
1
Condensate Sensor
Alarm Output (from
2
UPM)
Auxiliary Electric Heat
Second-Stage Auxiliary
Heat/Emergency Heat
Table 3 Low-Voltage Connection Points
Tables Notes:
1) If the condensate overflow sensor option is
utilized connect "CS" at the condensing section
to "CS" at the air handler. Be sure to ground
power supply.
2) If service LED is utilized connect "ALR" terminal
on the UPM board to "L" on the thermostat sub
base. The wiring may be spliced in the air
handling unit. The "ALR" output is hot (R) so
check thermostat instruction manual to ensure
compatibility.
3) "O" – reversing valve is energized in the cooling
mode. Fail safe is to heating.
4) Utilized when electric strip heater package
present.
5) Will vary depending on the thermostat.
8733826256 (2020/06)
From
Thermostat
C
R
G
O
Y1
Y2
—
L/ALR
4 W/W1/W2
5
W/E, W1/E, W2/E
4
Subject to change without prior notice
To Air Handler From Air
Handler
C
R
G
O
Y1
Y2
—
Splice
W1
W2
SM Split AH/AV Air Handler
To
Condensing
Section
C C
R R
— —
O O
Y1 Y1
Y2 Y2
CS CS
ALR (UPM)
— —
— —
SM Split AH/AV Air Handler