LAARS SC 12 - Install and Operating Manual - Manual (Page 6)

Page 6 LAARS Heating Systems
External Set Point - Terminals 4, 5, and 6
• The SC can accept a 4-20mA signal from an Energy Management System (EMS) or other signal
source to change the Set Point remotely (see pg. 23).
• Dip switch 6 and 8 must be OFF and dip switch 7 must be OFF OFF ON. These settings will allow the ON ON
SC to read and monitor the system water temperature using the System temperature sensor and
monitor the 4-20mA input to change the set point. (See wiring sensor on pg. 3) Also, see pg. 23 for
EMS programming parameters.
Shutdown or Setback - Terminals 7 and 77 8
• When adjusting control SETBACK Stb setting to 0 the SHUTDOWN feature is enabled by SHUTDOWN SHUTDOWN
closing a dry contact and all active stages are turned off. Any pumps controlled by the SC that
were on will remain on until the System Delay is over, then they will also turn off.
• The SHUTDOWN feature can be used whenever it is desirable to turn off the SC from a remote SHUTDOWN SHUTDOWN
location or another controller (for more details see pg. 24).
• When SETBACK Stb is enabled by adjusting control SETBACK Stb setting to a value higher
than 0 and closing a dry contact wired to terminals 7 and 8, the SC will immediately reduce the
temperature of the circulating hot water by the SETBACK Stb setting amount (see pg. 20 to
adjust the amount of SETBACK). All pumps controlled by the SC that were on will remain on until the
System Delay is over, then they will turn off.
• The SHUTDOWN/SETBACK signal must be a dry contact only to terminals 7 and 8. No voltage can be SHUTDOWN/SETBACK SHUTDOWN/SETBACK
placed across the SHUTDOWN/SETBACK terminals. SHUTDOWN/SETBACK SHUTDOWN/SETBACK
Prove or Domestic Hot Water (DHW) Input - Terminals 9 and 99 10
• The Prove or Domestic Hot Water features are set by the External Input Mode in the Power Up
Sequence. It can be switched between Prove (Pr) and Domestic Hot Water (dh).
• The PROVE feature is used to check system components’ operation before activating any stages. See PROVE PROVE
pg. 24 for typical applications.
• If the PROVE input terminals are open, the SC will enable only the System Output relay. All Stage PROVE PROVE
Outputs will be off when the PROVE input is open. PROVE PROVE
• When the Domestic Hot Water (DHW • When the Domestic Hot Water ( • When the Domestic Hot Water ( ) input is enabled by closing a dry contact, the Calculated water DHW DHW
temperature or the Set Point will change to 200°F and the decimal point on the left-most digit on the
display will fl ash.
• The DHW input will take priority over the outdoor reset function or the Outdoor Cutoff temperature. DHW DHW
Regardless of outdoor temperature, when the DHW input is closed, the SC will Sequence stages to DHW DHW
hold 200°F.
• If NO external conditions must be met before Stage Output is activated and terminals 9 and 10 are not used for Domestic Hot
Water (see pg. 25), DO NOT remove the factory installed jumper across the PROVE/DHW terminals. PROVE/DHW PROVE/DHW
• The PROVE/DHW signal must be a dry contact only to terminals 9 and 10. No voltage can be placed across the PROVE/DHW PROVE/DHW PROVE/DHW
terminals.
IMPORTANT FACTORY INSTALLED PROVE JUMPER: The PROVE input terminals must be PROVE PROVE
shorted for Stage Outputs to be activated. DO NOT remove the factory installed
PROVE jumper unless replacing it with a Prove or Domestic Hot Water signal.
Outdoor Sensor- Terminals 11 and 12
• The Outdoor Sensor must be installed if the Outdoor Reset operational mode is required (dip switch 8 ON). ON ON
• Installing the Outdoor Sensor is optional in the Set Point mode (dip switch 8 OFF). If it is installed, it will act as an Outdoor OFF OFF
Cutoff (see pg. 18). No stages will be activated when the outdoor temperature is above the Outdoor Cutoff.
• Locate the Outdoor sensor in the shade on the north side of the building away from doors,
windows, exhaust fans, vents, or other possible heat sources.
• The sensor should be mounted at least 4 inches away from the building wall and
approximately 10 feet above ground level.
• Sensor wires can be extended up to 500’ by splicing with 18 gauge shielded wire.
• Do not run sensor wire in conduit with line voltage.
• Temperature sensors have no polarity. Connect either wire to terminal 11 and 12.
• Connect the shield to terminal 3 SHIELD. Note that both sensor shields will be connected
to terminal 3.
Dry Contact
Prove or Domestic
Hot Water Signal
INPUTS
5 6 7 8 9 10 11
Sensor Com Dry Contact
Only
Dry Contact
Only
SHUTDOWN
/SETBACK
PROVE
/DHW
OUTD
4-20 ma
INPUTS
5 6 7 8 9 10 11 12
Sensor Com Dry Contact
Only
Dry Contact
Only
SHUTDOWN
/SETBACK
PROVE
/DHW
4-20 ma OUTDOOR
To Outdoor Sensor
In Shade
Shield
2 3 4
Com Shield +
TEMP
4 5 6
+ Sensor Com
4-20 ma
SC Source Current
24VDC Excitation Voltage
(-) Input
(+) Signal
INPUTS
5 6 7 8 9
Sensor Com Dry Contact
Only
Dry Contact
SHUTDOWN
/SETBACK
PROVE
4
+
4-20 ma
Dry Contact
Shutdown and
Setback Signal
4 5 6
+ Sensor Com
4-20 ma
EMS Sourcing Current
(-) Input
(+) Signal