Setting and using method
n For heat pump thermostat with O terminal signal input
AC 24 V
Thermostat Fan & System Switch
FAN
MODE
Thermal
Operation
[Auto / On]
[Cool / Heat / Off]
-
-
-
0
OFF
-
1
RT > SP
1
Cool
Auto
RT < SP
1
RT < SP
1
Heat
RT > SP
1
FAN
-
1
RT > SP
1
Cool
ON
RT < SP
1
RT < SP
1
Heat
RT > SP
1
Notes
• Thermostats that close contacts "O" or "B" during Cool or Heat call only have not been verified. "O"
and/or "B" contact closure must be maintained during respective cycle / mode selection.
• IDU Fan logic, depending on model selected, may delay IDU fan operation momentarily during a cold
start heat call. This function allows IDU coil to warm up prior to operating fan in some IDU models.
• Thermostats that use resistive anticipation are not supported at this time.
• Verify documentation of desired thermostat so that the logic is same as shown in the table above.
18 Dry contact for thermostat
Thermostat
LG does not supply this section
L
(Field supply)
N
L
L L
C
R Y G O
Input
IDU Response
FAN
COOL
[Mode / Thermal / Fan]
[Y]
[G]
[O]
-
-
-
Disable Operation
0
0
0
Off
1
0
1
Cool / On / On
0
0
1
Off
1
0
0
Heat/ On/On
0
0
0
Off
0
1
0
Fan/ Off/ On
1
1
1
Cool/ On/ On
0
1
1
Fan/ Off/ On
1
1
0
Heat/ On/ On
0
1
0
Fan/ Off/ On
※ RT : Room Temperature
※ SP : Set Point
n For heat pump thermostat with B terminal signal input
AC 24 V
Thermostat Fan & System Switch
FAN
MODE
Thermal
Operation
[Auto / On]
[Cool / Heat / Off]
-
-
-
0
OFF
-
1
RT > SP
1
Cool
Auto
RT < SP
1
RT < SP
1
Heat
RT > SP
1
OFF
-
1
RT > SP
1
Cool
ON
RT < SP
1
RT < SP
1
Heat
RT > SP
1
Notes
• Thermostats that close contacts "O" or "B" during Cool or Heat call only have not been verified. "O"
and/or "B" contact closure must be maintained during respective cycle / mode selection.
• IDU Fan logic, depending on model selected, may delay IDU fan operation momentarily during a cold
start heat call. This function allows IDU coil to warm up prior to operating fan in some IDU models.
• Thermostats that use resistive anticipation are not supported at this time.
• Verify documentation of desired thermostat so that the logic is same as shown in the table above.
Setting and using method
Thermostat
LG does not supply this section
L
(Field supply)
N
L L L
C
R Y G B
Input
IDU Response
FAN
HEAT
[Mode / Thermal / Fan]
[Y]
[G]
[B]
-
-
-
Disable Operation
0
0
0
Off
1
0
0
Cool / On / On
0
0
0
Off
1
0
1
Heat/ On/On
0
0
1
Off
0
1
0
Fan/ Off/ On
1
1
0
Cool/ On/ On
0
1
0
Fan/ Off/ On
1
1
1
Heat/ On/ On
0
1
1
Fan/ Off/ On
※ RT : Room Temperature
※ SP : Set Point
Installation manual 19