Carrier Omnizone 50BVC Installation, Start-Up, Service And Controls Operation And Troubleshooting page 26

Install the thermostat in the space where the temperature is being
controlled, according to the instructions provided with the thermo-
stat.
WARNING
Before wiring the thermostat to the unit, make sure that main
power to the unit has been disconnected. Failure to heed this
warning could result in personal injury.
To wire the thermostat:
1. Connect the 'C' terminal from the 50BV unit to the 'C' termi-
nal on the thermostat.
2. Wire the 'Y1' and 'Y2' terminals from the 50BV unit to the
'Y1' and 'Y2' terminals, respectively, at the thermostat.
3. Make a connection between the 'G' terminal on the unit and
the 'G' terminal on the thermostat.
4. Attach a wire from the 'R' terminal at the unit to the 'R' ter-
minal at the thermostat.
5. 50BVQ and 50BVV ONLY: If the unit is a heat pump, con-
nect a final wire from terminal 'O' on the heat pump unit to
the 'W1/O/B' terminal at the thermostat. Configure the ther-
mostat for heat pump operation using the installation instruc-
tions provided with the thermostat. Set the reversing valve
polarity of the thermostat to 'O'.
6. For units with cycling (on/off) HGRH, connect the thermostat
H output to the H terminal on the 50BV. Set up the thermostat
to provide an H output only, as the unit will automatically
enable the Y1 and O terminals when there is a call for H
(dehumidification).
See Fig. 21 for typical thermostat wiring.
50BVT,V044-064 Only
Unit sizes 044-064 have 4 independent refrigerant circuits. These
units can be controlled using a standard commercial, 2-stage ther-
mostat. In this case, the first stage of cooling will turn on compres-
sors 1 and 2, and the second stage will turn on compressors 3 and
4. It is also possible to have 4 stages of cooling, using a suitable
field-supplied control method.
For 2-stage thermostat wiring, refer to Fig. 21. Jumpers must be
installed between the G and O terminals in Modules A and B. A
field-supplied, 24-v pilot relay should be used to energize Y2 on
Module B whenever Y1 is energized on Module A. Similarly, a
field-supplied 24-v pilot relay should be installed to energize Y4
on Module B whenever Y3 on Module A is energized (Y2 stage of
thermostat calls for cooling).
Finally, verify that transformer phasing is consistent between
Modules A and B.
THERMOSTAT
B
O
Y2 R W1 Y1 G C
2nd STAGE COMPRESSOR RELAY
Fig. 20 — Typical Wiring Unit Sizes 020-034
(Two-Stage Cooling Units)
26
TYPICAL
UNIT
24 VAC COMMON
FAN RELAY
COMPRESSOR RELAY
HEAT PUMP
24 VAC RETURN
C
O
Y1
Y2
R
G