38Audc With Svr Relays; All Units - Carrier Gemini 38AU07 Series Installation Instructions Manual

WATCH
YOUR
SUCTION
RISERS
LIQ INJ BULB
TO SUCTION LINE
SOLENOID
VALVE
Fig. 34 — Location of Hot Gas Bypass in 38AUDC12
SUCTION LINE
HOT GAS
DE-SUPERHEAT
CHAMBER
HOT GAS BULB
TO SUCTION LINE
AND INSULATE
SCHRADER VALVE
AT BOTTOM
COMPRESSOR
Fig. 33 — Hot Gas Bypass Option
Hot Gas Bypass
Factory Installed
Option
33
EVAPORATOR
COIL
HOT GAS LINE

38AUDC with SVR Relays

With no thermostat demand, there will be no voltage at
LVTB-A1; HGBP SOLENOID is de-energized and solenoid
valve remains closed, preventing bypass vapor from the desu-
perheating tank to enter the suction line at the compressor.
On a thermostat call for first-stage cooling, LVTB terminal
Y1 is powered; when CADM1 is satisfied, compressor con-
tactor C1 and Solenoid Valve Relay SVR1 are energized.
SVR1 contacts close, providing 24-v to LVTB terminal A1,
then through HGBP RELAY NC contacts to HGBP SOLE-
NOID. HGBP solenoid valve opens, allowing bypass vapor
from the desuperheating tank to enter the compressor suction
port.
If thermostat calls for second stage cooling, LVTB termi-
nal Y2 is powered; when CADM2 is satisfied, compressor
contactor C2, Solenoid Valve Relay SVR2 and HGBP RE-
LAY are energized. HGBP RELAY NC contacts open, de-en-
ergizing the HGBP SOLENOID; solenoid valve closes,
blocking bypass vapor from the desuperheating tank and unit
runs at full cooling capacity.
The model 38AUDC also includes the 32LT Motormaster
low ambient control as a standard feature. Refer to Appendix
C for information on the Motormaster control.

All Units

If either the Low Pressure Switch or High Pressure Switch
opens while thermostat output Y1 or Y2 remain energized,
the compressor contactor is de-energized, the compressor
stops and liquid line solenoid is de-energized (valve closes).
CADM initiates a TRIP event (cooling demand sensed at
CONDENSER
COIL