LAARS SC 12 - Install and Operating Manual - Manual (Page 7)

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 Cutoff + 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 Cutoff + 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.