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Laars Sequencing Controls

Document 4200

LINE

NEUT

OUTPUT 8

OUTPUT 9

OUTPUT 7

OUTPUT 10

OUTPUT 11

OUTPUT 12

INCREMENT

AUTO

OFF

LEAD STAGE

ROTATION

SELECT

SETTING

UP

DOWN

INPUTS

1 2 3 4 5 6 7 8 9 10

SAFETY

GROUND

MUST BE

CONNECTED

11 12

Sensor Com Shield

+

Sensor Com

Dry Contact

Only

Dry Contact

Only

TEMP

SHUTDOWN

/SETBACK

PROVE

/DHW

SYSTEM

Output 7

OFF

AUTO

ON

Output 8

OFF

AUTO

ON

Output 9

OFF

AUTO

ON

Output 10

OFF

AUTO

ON

Output 11

OFF

AUTO

ON

Output 12

OFF

AUTO

ON

OFF

AUTO

ON

OUTPUT 1

OUTPUT 2

OUTPUT 3

OUTPUT 4

OUTPUT 5

OUTPUT 6

Output 1

OFF
AUTO
ON

Output 2

OFF
AUTO
ON

Output 3

OFF
AUTO
ON

Output 4

OFF
AUTO
ON

Output 5

OFF
AUTO
ON

Output 6

OFF
AUTO
ON

System

LEAD

OUTPUT ON

4-20 ma

OUTDOOR

SC

Non-Modulating

Model SC6, SC6P

and SC 12

Output panel to Sequence

up to 12 individual

stages with lead-lag and

manual override capabilities

Installation and Operation Instructions

FOR YOUR SAFETY:

  

This product must be installed and serviced by a 

professional service technician, qualifi ed in hot water heater/boiler controls 

installation and maintenance.  This manual is intended for anyone who will 

install, operate or maintain the control system.  Before you begin installation 

and operation of this control, it is important that you thoroughly review this 

manual.  Improper installation and operation could result in damage to 

equipment and possibly even personal injury.  Laars Sequencing Controls are 

not intended for use as operation safety limit controls. Another control, which 

is intended and certifi ed as a high limit control, must be in the boiler/heater 

control circuit.

Summary of Contents for SC 12

Page 1: ...4 20 ma OUTDOOR SC Non Modulating Model SC6 SC6P and SC 12 Output panel to Sequence up to 12 individual stages with lead lag and manual override capabilities Installation and Operation Instructions FOR YOUR SAFETY This product must be installed and serviced by a professional service technician qualified in hot water heater boiler controls installation and maintenance This manual is intended for any...

Page 2: ...SWITCH 8 OFF 10 SET POINT CONTROL WITH OSS SEQUENCING 11 OUTDOOR RESET WITH NORMAL SEQUENCING 12 OUTDOOR RESET WITH OSS SEQUENCING 13 SC 6 AND SC 12 OUTPUT WIRING 14 WIRING THE STAGE OUTPUTS 14 SC 6P OUTPUT WIRING 15 WIRING THE STAGE OUTPUTS 15 SAMPLE WIRING AND PLUMBING DIAGRAMS 16 OUTPUT RELAY CHARTS 17 OPERATION 18 SET POINT CONTROL SETTINGS 18 OUTDOOR RESET SETTINGS 19 NORMAL SEQUENCING SETTIN...

Page 3: ... ON Output 5 OFF AUTO ON Output 6 OFF AUTO ON System LEAD OUTPUT ON 4 20 ma OUTDOOR SC Digital display reads sensor value constantly Install a relay for each output stage which will be active Use these three buttons to adjust the settings In AUTO the lead stage will automatically rotate among the active outputs Press to INCREMENT for manual rotation Each Stage Output has one set of N O contacts Th...

Page 4: ...Point control for temperature 8 Outdoor Reset Hydronic heating control with outdoor reset ON ON 1 System Pump SYSTEM relay is on based on outside temp Shutdown and DHW priority 1 Combustion Air Damper Prove SYSTEM relay is on when any OUTPUT is on ON ON Switches 2 3 and 4 Stage Type 2Stage Lo Lo Hi Hi On load increase sequence on Lo stages first then Hi stages 2 On Off Stages Each stage is either ...

Page 5: ...ter the enclosure through a different opening from any Class 2 voltage wiring Connect the hot line to terminal marked LINE Connect the neutral line to the terminal marked NEUT The green ground screw must be connected to earth ground Wiring a surge suppressor is recommended before wiring to the SC Control WIRING THE INPUT TERMINALS System Temperature Sensor Terminals 1 2 and 3 The System Temperatur...

Page 6: ...ntact the Calculated water DHW input is enabled by closing a dry contact the Calculated water DHW temperature or the Set Point will change to 200 F and the decimal point on the left most digit on the display will flash The DHW input will take priority over the outdoor reset function or the Outdoor Cutoff temperature DHW input will take priority over the outdoor reset function or the Outdoor Cutoff ...

Page 7: ... 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 priori...

Page 8: ...crease the value DOWN button to decrease the value DOWN When the correct value is shown release the button and wait approximately 5 seconds If any changes were made the display will flash Set the Sequencing Mode Default Normal For most applications the Normal or PID type Sequencing mode provides the most stable operation Stages are turned on or off Normal or PID type Sequencing mode provides the mo...

Page 9: ...OWN button to decrease the value DOWN When the correct value is shown release the button and wait approximately 5 seconds If any changes were made the display will flash Set the Sequencing Mode Default Normal nor For most applications the Normal or PID type Sequencing mode provides the most stable operation Stages are brought on or off based on the rate of change of the system temperature and the i...

Page 10: ...e System Delay is adjustable from 0 to 30 minutes Default is 0 5 or 6 Times Purge Time The Purge Time should be set to the length of the unit s purge cycle The Purge Time will apply when any ON OFF unit is activated On multiple stage units the Purge Time will only apply to the Lo stages The Purge Time is adjustable from 0 0 to 10 0 minutes Default is 0 6 or 7 Times Boiler runtime This is the minim...

Page 11: ...nt With a known 4mA input the offset can be set to make the External Set Point 110 F The Program Offset is adjustable between 10 F to 10 F Default is 0 F 4 or more Times Throttling Range The throttling range sets the number of degrees or psi above and below the Set Point where stages will be turned on or off The Throttle Range is adjustable from 1 F to 20 F Default is 5 F See page 24 for details 5...

Page 12: ...will remain energized after the last Output has been turned off or the outdoor temperature rises above the Starter The System Delay is adjustable from 0 to 30 minutes 8 Times Purge Time The Purge Time should be set to the length of the unit s purge cycle The Purge Time will apply when any ON OFF unit is activated On multiple stage units the Purge Time will only apply to the Lo stages The Purge Tim...

Page 13: ...regardless of outdoor temperature or the reset curve selected The Offset is adjustable from 40 F to 40 F Default is 0 F 6 Times System Delay The System Delay controls how long the System relay will remain energized after the last Output has been turned off or the outdoor temperature rises above the Starter The System Delay is adjustable from 0 to 30 minutes 7 Times Throttling Range The throttling ...

Page 14: ...ally Open N O relay contact The N O contacts are dry contacts only They do not source any voltage Each N O contact is capable of switching 6A resistive Total output of all stages including the SYSTEM must not exceed 15A ON OFF Units Each unit has one relay and one set of Stage OUTPUT contacts associated with it OUTPUT contacts associated with it OUTPUT Wire the N O relay contacts in series with th...

Page 15: ...to the Hi control circuit 3 Stage Lo Mid Hi Units Each unit has one pump relay and three stage relays associated with it Check the chart for the Pump Lo Mid and Hi OUTPUT positions OUTPUT positions OUTPUT Connect the N O pump relay contacts in series with the unit s pump starter Connect the Lo N O relay contacts in series with the unit s limit circuit Connect the Mid N O relay contacts to the Mid ...

Page 16: ...Inputs Pump 3 Pump 2 Pump 1 Pump 3 Pump 2 Pump 1 Connect to 120VAC see page 5 Plumbing Class 1 Wiring Class 2 Sensor Wiring The laars SC Sequencing control DOES NOT source power for boiler stages or pumps It operates as dry contact switch A separate power source for the burners and pumps must be supplied 1 Laars is aware that each installation is unique Thus Laars is not responsibe for any install...

Page 17: ...re HiFire HiFire LoMid LoMid Output 7 Limit Limit Limit Limit Limit Limit Limit Limit Limit Limit Limit HiMid HiMid Output 8 Limit Limit Limit Limit Limit HiFire HiFire HiFire MidFire MidFire HiFire HiFire Output 9 Limit Limit Limit Limit Limit Limit HiFire HiFire Limit Output 10 Limit Limit Limit HiFire HiFire Limit LoMid Output 11 Limit Limit Limit MidFire HiMid Output 12 Limit HiFire HiFire HiF...

Page 18: ...not register a fault from the Outdoor sensor OPn Open or SHt short For heating when the Outdoor temperature drops below the Outdoor Cutoff temperature the SC will begin to Sequence stages for heat It will continue to Sequence until the Outdoor temperature rises to 2 F above the Outdoor Cutoff temperature The Outdoor Cutoff temperature can be set from 40 to 100 F In addition an ON setting is provid...

Page 19: ...or heat It will continue to Sequence until the Outdoor temperature rises to 2 F above the Outdoor Cutoff temperature The Outdoor Cutoff temperature can be set from 40 to 100 F In addition an ON setting is provided to override the Outdoor Cutoff for continuous Sequencing and an OFF setting can be used to temporarily prevent any Sequencing The Outdoor Cutoff has a built in 2 F differential If the Ou...

Page 20: ...ature display flashing the new value NORMAL SEQUENCING SETTINGS REACTION TIME Rt Default 2 minutes The Reaction Time controls how Output Stages are Sequenced on and off based on PID type logic Shorter Reaction Times allow Output Stages to be Sequenced more quickly and are appropriate for systems with many small stages where any single stage does not significantly change the total output Longer React...

Page 21: ...r Calculated water temperature to allow the Output Stage to run longer and therefore also be off longer before restarting The Last Stage Hold provides an adjustable temperature value which is added to the Set Point or Calculated water temperature When heating the SC will keep the last Output Stage running until the System temperature exceeds the Set Point or Calculated water temperature plus the L...

Page 22: ...age The Output with the green light on is currently the Lead Stage Only one Stage Output can be the Lead Stage at any given time The Lead Stage is always the first stage brought on when there is a call for output LEAD STAGE SWITCH The LEAD STAGE switch controls the rotation of the Stage Outputs LEAD STAGE switch controls the rotation of the Stage Outputs LEAD STAGE A unit can not be lead if any of ...

Page 23: ... position OFF position OFF OUTPUT LIGHTS The row of red lights marked OUTPUT ON indicate which outputs are energized If the red light next to a Stage Output is on then its output relay should be energized and the output contacts should be continuous If the red light next to a Stage Output is off the output relay should not be energized and the output contacts should be open EXTERNAL SET POINT The ...

Page 24: ...st be continuous for any Stage Output to be active If the PROVE PROVE inputs are opened when Stage PROVE inputs are opened when Stage PROVE Outputs are active then they will immediately de energize and the individual Pump Outputs on the SC 6P will de energize after the System Delay time The Prove function is the default value for Input terminals 9 and 10 However the same input terminals can be pro...

Page 25: ...t will close the DHW input terminals DHW input terminals DHW If the System Output is configured for Combustion Air Damper operation the System relay output will be closed when any Stage Output is activated to hold the 200 F set point If the System Output is configured for System Pump operation without DHW priority see pg 22 then the System relay will be closed whenever the outdoor temperature is bel...

Page 26: ...r Temperature Display Outdoor Temperature Display shows SHt The SC sees a short across the input terminals Remove the wires from the OUTDOOR 11 and 12 and 12 and inputs The display should change to read OPn If it doesn t the SC may be damaged Outdoor Temperature Display shows an Incorrect Reading Remove the wires from the OUTDOOR 11 and 12 inputs The outdoor temperature display should change to re...

Page 27: ...nit being energized to determine why it is not operating Red stage light is lit but the unit is not on The SC is calling for this unit to be on Follow the procedure above Red stage light is not lit but the unit is on SC N O contacts If there is no continuity the SC output is working correctly Check the unit for any other operating controls which may be causing it to run Stage Outputs don t Sequenc...

Page 28: ...ervice Service Advisors 20 Industrial Way Rochester NH 03867 603 335 6300 Fax 603 335 3355 1869 Sismet Road Mississauga Ontario Canada L4W 1W8 905 238 0100 Fax 905 366 0130 www Laars com Litho in U S A Laars Heating Systems 0806 Document 4200 ...

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