Page 1
SC-LLC-200
LEAD/LAG CONTROLLER
INSTALLATION INSTRUCTIONS
Page 2
INTRODUCTION
The SC-LLC-200 from Specified Controls is a versatile, 24VAC powered lead/lag controller offering
true dual stage control to balance the operating run time between HVAC equipment as well as
other redundant devices. The controller has dedicated terminals for 24VAC power, 2 inputs and 2
outputs. LEDs provide visual indication for power and output status.
SEQUENCE OF OPERATION
When 24 Volt power is first applied to the 24VAC terminals 7and 8 on the SC-LLC-200, Unit 1 and
Unit 2 output contacts remain open. When 24 Volts is applied to input terminal 1, Unit 1 output
contacts go closed and Unit 2 contacts remain open. When 24 Volts is removed from terminal 1 for
at least 10 seconds, Unit 1 output contacts open. When 24 Volts is reapplied to terminal 1, Unit 1
output contacts remain open and Unit 2 output contacts go closed. The lead/lag sequence is
reversed every time 24 Volts is removed from terminal 1 for more than 10 seconds and then
reapplied.
In a dual stage application, 24 Volts applied to terminal 2 will close the lag output contacts. As long
as 24 Volts is maintained on terminal 1, the lag output can be cycled on and off.
The SC-LLC-200 Lead/Lag Controller must be powered from the same 24 Volts as Unit 1 control
circuit or a relay will be required.
WIRING DIAGRAMS
The wiring diagrams illustrated in this installation manual represent a sampling of the many ways
the SC-LLC-200 can be applied for lead/lag control.
The SC-LLC-200 is an operating controller only and depending on the application, it is the
responsibility of the installer to verify that the SC-LLC-200 complies with all electrical and/or
plumbing codes.
SPECIFICATIONS
Input: 24 VAC
Frequency: 60/60 Hz
Contact Rating: 12 Amps @ 24 VAC
PC Board Dimensions: 3.25” W x 5.5” H
Mounted on Snap-Track
Controller With SC-LLC-200-ME with metal enclosure
Optional Enclosures: SC-LLC-200-WPE with weather-proof plastic enclosure
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
06-1072-083011
Page 3
SC-LLC-200
LEAD/LAG CONTROLLER
STAND ALONE APPLICATIONS
TYPICAL WIRING DIAGRAMS
Page 4
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER WITH
SINGLE-STAGE COOLING UNITS IN PARALLEL
SC-LLC-200
LEAD/LAG
CONTROL
HVAC UNIT 1
HVAC UNIT 2
Y1
Y1
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
G
R
X
G
R
C
SINGLE-STAGE STAT
G
R
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 5
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER WITH
SINGLE-STAGE COOLING UNITS IN PARALLEL
WITH UPSTAGING
SC-LLC-200
LEAD/LAG
CONTROL
HVAC UNIT 1
HVAC UNIT 2
Y1
Y1
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
G
R
X
G
R
C
MULTI-STAGE STAT
G
R
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 6
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER FOR
2 PUMP SYSTEM WITH A FLOW SWITCH TO
TRIGGER LEAD/LAG
SC-LLC-200
LEAD/LAG
CONTROL
24V R
Unit 2
Unit 2
24V C
TRANSFORMER
24V LINE
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
CONTROLLER
PUMP 2 RELAY
24 V
RY-1
COIL
NC C NO
24 V
RY-1
COIL
NC C NO
PUMP 1 RELAY
PUMP
120V / 240V
POWER
FLOW SWITCH
PUMP 1 PUMP 2
120V / 240V
POWER
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 7
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER FOR
2 PUMP SYSTEM WITH A RELAY TO
TRIGGER LEAD/LAG
SC-LLC-200
LEAD/LAG
CONTROL
24V R
Unit 2
Unit 2
24V C
TRANSFORMER
24V LINE
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
CONTROLLER
PUMP 2 RELAY
24 V
RY-1
COIL
NC C NO
24 V
RY-1
COIL
NC C NO
PUMP 1 RELAY
PUMP
120V / 240V
POWER
PUMP 1 PUMP 2
120V / 240V
POWER
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 8
Page 9
SC-LLC-200
LEAD/LAG CONTROLLER
USED WITH SC-SC-TK-400 TWINNING
AND PARALLELING KIT
TYPICAL WIRING DIAGRAMS
Page 10
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER AND
SC-SC-TK-400 TWINNING KIT FOR COOLING LEAD/LAG
SC-SC-TK-400
Y1
W1
G
R
X
SINGLE-STAGE STAT
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1
HVAC UNIT 2
Y1
W1
Y1
W1
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC Unit 1HVAC UNIT 2
X
Y1
Y2
W1
W2
G
G
O/B
R
R
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 11
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER AND
SC-TK-400 TWINNING KIT FOR COOLING LEAD/LAG WITH UPSTAGING
SC-TK-400
Y1
Y2
W1
W2
G
R
X
MULTI-STAGE STAT
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1
HVAC UNIT 2
Y1
W1
Y1
W1
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC Unit 1HVAC UNIT 2
X
Y1
Y2
W1
W2
G
G
O/B
R
R
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 12
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER AND
SC-TK-400 TWINNING KIT FOR HEATING LEAD/LAG
SC-TK-400
Y1
W1
G
R
X
SINGLE-STAGE STAT
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1
HVAC UNIT 2
Y1
W1
Y1
W1
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 1
X
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 2
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 13
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLER AND
SC-TK-400 TWINNING KIT HEATING LEAD/LAG WITH UPSTAGING
SC-TK-400
Y1
Y2
W1
W2
G
R
X
MULTI-STAGE STAT
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1
HVAC UNIT 2
Y1
W1
Y1
W1
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 1
X
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 2
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 14
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLERS AND
SC-TK-400 TWINNING KIT FOR HEATING AND COOLING LEAD/LAG
SC-TK-400
Y1
W1
G
R
X
SINGLE-STAGE STAT
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1HVAC UNIT 2
Y1
W1
Y1
W1
SC-LLC-200
LEAD/LAG
CONTROL
SC-LLC-200
LEAD/LAG
CONTROL
(HEATING) (COOLING)
24V R
Unit 2
Unit 2
24V R
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Unit 2
Unit 2
24V C
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 1HVAC UNIT 2
X
Y1
Y2
W1
W2
G
G
O/B
R
R
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 15
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLERS AND
SC-TK-400 TWINNING KIT FOR HEATING AND COOLING
LEAD/LAG WITH UPSTAGING
SC-TK-400
Y1
Y2
W1
W2
G
R
X
MULTI-STAGE STAT
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1HVAC UNIT 2
Y1
W1
Y1
W1
SC-LLC-200
LEAD/LAG
CONTROL
SC-LLC-200
LEAD/LAG
CONTROL
(HEATING) (COOLING)
24V R
Unit 2
Unit 2
24V R
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Unit 2
Unit 2
24V C
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 1HVAC UNIT 2
X
Y1
Y2
W1
W2
G
G
O/B
R
R
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 16
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLERS AND
SC-TK-400 TWINNING KIT FOR 1 HEAT / 1 COOL HEAT PUMP
SC-TK-400
HEAT PUMP STAT
Y1
G
O/B
R
X
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1HVAC UNIT 2
Y1
O/B
Y1
O/B
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 1
X
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 2
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 17
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLERS AND
SC-TK-400 TWINNING KIT FOR 1 HEAT / 1 COOL HEAT PUMP
WITH UPSTAGING
SC-TK-400
HEAT PUMP STAT
Y1
Y2
G
O/B
R
X
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1HVAC UNIT 2
Y1
O/B
Y1
O/B
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 1
X
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 2
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
Page 18
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLERS AND
SC-TK-400 TWINNING KIT AND RY-2 DPDT RELAY FOR
2 HEAT / 1 COOL HEAT PUMP
SC-TK-400
HEAT PUMP STAT
Y1
W
G
O/B
R
X
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1HVAC UNIT 2
Y1
O/B
Y1
W
O/B
W
G
R
G
R
X
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
O/B
R
HVAC UNIT 1
X
Y1
Y2
W1
W2
G
O/B
R
HVAC UNIT 2
R
24V
X
NC C NO NC C NO
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
24V
Page 19
WIRING DIAGRAM USING SC-LLC-200 LEAD/LAG CONTROLLERS AND
SC-TK-400 TWINNING KIT FOR 2 HEAT / 1 COOL HEAT PUMP
WITH UPSTAGING
(Auxiliary / EH Heat Work Together)
SC-TK-400
HEAT PUMP STAT
Y1
Y2
W
G
O/B
R
X
SC-LLC-200
LEAD/LAG
CONTROL
Y1
Y2
W1
W2
G
O/B
R
X
TERMINALS
THERMOSTAT
HVAC UNIT 1HVAC UNIT 2
Y1
W1
O/B
Y1
W1
O/B
24V R
Unit 2
Unit 2
24V C
Unit 1
Unit 1
Signal 1 IN
Signal 2 IN
1 2 3 4 5 6 7 8
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 1
X
Y1
Y2
W1
W2
G
R
G
O/B
R
HVAC UNIT 2
X
R
24V
X
5351 East Thompson Road, Suite 128, Indianapolis, IN 46237
Phone 888.359.0365
www.specifiedcontrols.com
SC-06-1196-062314
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