LAARS SC 12 - Install and Operating Manual - Manual (Page 22)

Page 22 LAARS Heating Systems
SYSTEM OUTPUT SETTINGS
SYSTEM DELAY (Sd) Default: 0 minutes
SC-6 or SC-12
• In Combustion Air Damper mode (Dip Switch 1 = OFF) when the last Stage Output relay is turned off, the System Output Relay
will remain energized for a period set by the System Delay.
• In System Pump mode (Dip Switch 1 = ON) when the Outdoor Cutoff + 2°F is reached, the System Output Relay will remain
energized for a period set by the System Delay.
• The System Delay can be set from 0 to 30 minutes. If the setting is 0, the System Output will turn off immediately when the last
Stage Output turns off.
SC-6P
• The System Delay time applies to the System Output and the boiler Pump Outputs (see chart on pg. 17).
• Each individual boiler Pump will activate when the individual boiler is activated (the Lo Stage Output is activated). After the
specifi c boiler (the Lo Stage Output) is turned off, that specifi c Pump will remain energized for the period of time set by the
System Delay. That is, when any specifi c boiler is turned off, its Pump Output will continue to run on for the period of time set
by the System Delay.
• When the last Pump Output turns off, the System Output will remain energized for the period of time set by the System Delay.
DOMESTIC HOT WATER PRIORITY TIME (dhP) Default: 0 minutes
• This option is available in either Set Point or Outdoor Reset, when dip switch 1 is ON for System Pump operation. ON ON
• When there is a call for DHW, it may be desirable to turn off the System Pump that provides heating water to the building. This
will allow the DHW call to be satisfi ed more quickly.
• However, if the DHW call is not satisfi ed after a certain period of time, the System Pump must be reactivated to once again
provide heat to the building.
• The Domestic Hot Water Priority sets the amount of time the System Pump will be disabled for a DHW call. It is adjustable from
0 to 4 hours in half hour increments.
LEAD STAGE
REMEMBER
Only On/Off Boilers or Lo-Fire stages can be a lead stage.
LEAD STAGE LIGHTS
• The row of green lights marked LEAD indicate which Stage Output is currently the Lead Stage.
• 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 fi rst 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 LEAD STAGE
• A unit can not be lead if any of its OFF/AUTO/ON switches is not set to OFF/AUTO/ON OFF/AUTO/ON AUTO (see pg. 23). Any unit which has one or more of
its stages switched ON or ON ON OFF is not considered as part of the rotation. OFF OFF
• Only the Lo stages of any multistage units can be selected to be lead (see chart on pg. 17).
• If the LEAD STAGE switch is in the LEAD STAGE LEAD STAGE OFF position, whichever stage is presently the Lead Stage will always remain the Lead OFF OFF
Stage until there is a power failure. Then the SC will revert back to the fi rst possible lead stage.
• To change the current lead stage, press the LEAD STAGE switch to the LEAD STAGE LEAD STAGE INCREMENT position and then release it. The green INCREMENT INCREMENT
light indicating Lead Stage will increment to the next available stage.
• To automatically rotate the lead stage, switch the LEAD STAGE switch to the LEAD STAGE LEAD STAGE AUTO position (see rotation types below).
FIRST ON/LAST OFF ROTATION
• For this type of rotation, dip switch 5 must be in the OFF position. OFF OFF
• On power up, or any time the SC loses power, the Lead Stage will be the fi rst possible lead stage.
• After the fi rst 12 hours of power, the Lead Stage will change to the next possible stage.
• Subsequently, every 24 hours, the Lead Stage will change to the next possible stage.
• The Lead Stage will always be the fi rst stage brought on when there is a call for output.
• As more output is needed, additional stages are added.
• When less output is needed, the additional stages are turned off in the reverse order of how they were added. For instance, if the
stages were added in the Sequence 1, 2, and 3, then they will be turned off in the Sequence 3, 2, and fi nally 1.