Venstar T7900 - Manual (Page 88)

80
Installation Instructions
Sample Wiring Diagrams
with Dip Switch Positions
Heat Pump Systems with Dual Fuel
Free Cooling utilizes the Y1 terminal for the operation of 1st stage cooling.
If mechanical (compressor) cooling is also present, the mechanical cooling is
connected to the Y2 terminal in this instance.
Free Cooling may be used with a Gas/Electric or Heat Pump system.
Temperature Sensor: ACC-TSEN Temperature Sensor 10K ohm sensor
at 77F/25C. Negative Temperature Coefficient.
Residential & Commercial Heat Pump with
‘O’ Reversing Valve and Fossil Fuel furnace.
7 Wire, 2 Stage Cooling, 3 Stage Heat
R 24VAC Power
C 24VAC Common
W1/O/B Reversing Valve
W2 3rd Stage Heat
(connected to furnace)
Y1 1st Stage Compressor
(Cool or Heat)
Y2 2nd Stage Compressor
(Cool or Heat)
G Fan
Number of Compressor Stages
set to 2
Dual Fuel set to On
Free Cooling
Free Cooling
Damper
C R G Y1 Y2 W1/O/B W2 W3
10K Thermistor
Outdoor Sensor
GAS/EL HP
O
GAS
B
ELEC 12
3
ON
Use 18-22 gauge thermostat wire.
SENSOR
(see Dual Fuel Settings, pg. 36)
(see Compressor Stages, pg. 33)
ACC-TSEN