Page 7
Laars Sequencing Controls
WIRING THE STAGE OUTPUTS
• For SC-6 and SC-12 see pg. 14.
• For SC-6P see pg. 15.
WIRING THE SYSTEM OUTPUT
Combustion Air Damper
• To select the Combustion Air Damper mode of operation, Dip Switch 1 must be
OFF
.
• Wire the Air Damper to System relay terminals marked C and N.O.
• The Combustion Air Damper option causes the System relay to act as follows:
- If there is no call for stage output, the System relay is off
- On a call for stage output, the System relay is energized
- When the
PROVE
input is made, the lead stage is energized
PROVE
PROVE
- The System relay remains energized as long as any stage is active
- When the last stage turns off, the System relay remains energized for the period of
time set by the System Delay (see pg. 22)
- Then the System relay is turned off.
• To give the damper time to open, wire the damper motor end switch into the
PROVE
inputs. The
PROVE
PROVE
PROVE
input can be used in a
PROVE
PROVE
similar fashion to provide a delay for any equipment being energized by the System relay.
• The Combustion Air Damper operation can also be used to activate any piece of equipment that should be on whenever any stage
is active or can provide a signal to other equipment that one or more stages of the SC has been activated.
• The System Relay is a SPDT output capable of switching 6A resistive.
• Check the wiring information provided by the damper motor or other equipment manufacturer for the appropriate method to
activate the equipment with a SPDT output.
System Pump
• To select the System Pump mode of operation, Dip Switch 1 must be
ON
.
ON
ON
• Wire the System Pump to System relay terminals marked C and N.O.
• When there is no call for DHW, the System relay will be energized whenever the
Outdoor temperature is below the Outdoor Cutoff
COF
and the Shutdown is not
active. The System relay will remain energized even if all Output Stages are off.
• If an outdoor sensor is not connected or registers a fault condition:
- The System relay will be energized when any stage is active
- After the last stage is turned off, the System relay will remain energized for the period of time set by the System Delay (see pg.
22) and then turn off.
• When the control is set for “no DHW priority” (see pgs. 8 and 9) and there is a call for DHW:
- When the outdoor temperature below the Outdoor 2°F (
COF
+ 2°F), the System relay output will be active.
- Otherwise, the System relay will be off above
COF
+ 2°F (after the System Delay
Sd
has expired).• When the control is set
for “DHW priority” (see pgs. 8 and 9):
• When the control is set for “DHW priority” (see pgs. 8 and 9):
- The System relay will be off for an adjustable period of time set by the DHW Priority Time
dhP
.
- After the Priority Time has elapsed, when the outdoor temperature is below the Outdoor 2°F (
COF
+ 2°F) setting, the
System relay will be energized.
- When the outdoor temperature is 2°F above the Outdoor Cutoff (
COF
+
2°F), the System relay will be off at all times.
• The system output is capable of switching 6A resistive.
BEFORE POWER UP
• The dip switches must be set correctly for the application. Check the dip
switch chart on pg. 4 to make sure the SC is set properly before power up.
• Each Stage Output which is to be active (and has a relay installed) should have its
OFF/AUTO/ON
switch in the
OFF/AUTO/ON
OFF/AUTO/ON
AUTO
position.
• Any Stage Output which is not to be active (or any output without a relay) should have its
OFF/AUTO/ON
switch in the
OFF/AUTO/ON
OFF/AUTO/ON
OFF
position.
• Set the
LEAD STAGE
switch in the
LEAD STAGE
LEAD STAGE
AUTO
position for automatic rotation.
SYSTEM
C.
N.C.
N.O.
Combustion
Air Damper
Li
ne
N
eu
t
SYSTEM
C.
N.C.
N.O.
System Pump
Li
ne
N
eu
t
WARNING
WARNING
The SC is NOT a safety
control. Make sure damper
is wired back into boiler for
safety.
NOTICE
The SC DOES NOT source
power. A separate power
source must be supplied for
equipment being controlled.
