Installation Guide
INSTALLATION 
9 
LOW VOLTAGE CONTROL WIRING
1. Field installed low voltage control
wiring must be a minimum of 18AWG.
2. Low voltage provided by terminal “R” in
Indoor Unit is 24VAC.
3. Terminal “G” in Outdoor Unit is not used
and does not require any field wiring to be
connected to this terminal.
4. 4-Way Valve (Reversing Valve) is energized
by terminal “B” in the Heating Mode and
must be configured accordingly at the field
installed thermostat.
5. Break “R” or “Y” from thermostat when using a field installed Condensate Overflow Safety.
It is the licensed HVAC 
installing contractors 
responsibility to install the 
Low Voltage Control Wiring 
in accordance with any 
prevailing local, state, and 
federal codes and 
regulations. 
3.6 Optional Electric Heater……………………………………………………… 
Indoor Unit Model 
Cooling 
Capacity 
Electric Heater 
Model 
Electric Heater 
Size (kW) 
FLEXX24 / 36HP230V1BH  24K / 36K  FLEXXHTR5KW  5 
FLEXX24 / 36HP230V1BH  24K / 36K  FLEXXHTR8KW  8 
FLEXX36 / 48 / 60HP230V1BH  36K / 48K / 60K  FLEXXHTR10KW  10 
FLEXX48 / 60HP230V1BH  48K / 60K  FLEXXHTR15KW  15 
FLEXX48 / 60HP230V1BH  48K / 60K  FLEXXHTR20KW  20 
NOTES: 
1. Optional Electric Heater “Sold Separately”.
2. When Optional Electric Heater is installed, Indoor Unit power supply must be connected to
circuit breakers provided with Electric Heater. *Refer to Electric Heater Installation
Instructions for all electrical requirements*
For more information on the optional Electric Heater, power supply requirements, and step-by-
step installation instructions please visit www.greecomfort.com or use the camera on your smart 
phone to scan the QR code below: 
NOTE: 
Y means Compressor control signal for the outdoor unit; 
B which is energized under the heating mode means 4-way valve control 
signal; 
D means defrosting signal; 
R means 24V AC power supply; 
C means 24V common; 
G means indoor unit fan signal for the indoor unit; 
W1 means heater control signal. 
NOTE: 
For cooling only unit, there is no need to connect the B and D 
terminals. 
NOTE:
 When outdoor defrosts, D of outdoor unit will send 24V signal to avoid 
cold winds. 
NOTE: 
When the electric heating operate, the indoor unit is forced to open the 
indoor unit fan. 
①. High and low voltage wires should be led through different rubber rings of
 the electric box cover.
②. Do not bundle up the thermostat wires or lay them side by side, otherwise errors will occur.
③. High and low voltage wires should be secured separately. Secure the former ones with big clamps and the latter ones with small clamps.
④. Use screws to tighten up the thermostat wires and power cords of unit on the terminal board. Wrong connection may lead to fire hazard.
⑤. If the thermostat wires of unit and power cords are not correctly connected, the air conditioner may get damaged.
⑥. Ground the unit through connecting the ground wire.
⑦. The units should comply with applicable local and national rules and regulations on power consumption.
⑧. When connecting the power cords, make sure the phase sequence of the power supply matches with the corresponding terminals,
otherwise the compressor will get reversed and operate abnormally.










