LAARS S8Ext - Installation Manual - Manual (Page 21)

Page 21 LAARS Sequencing Controls S8 & S8EXT
• To Set the first point, specify Sys Temp 1, and OD Temp 1. Then, specify Sys Temp 2, and OD Temp 2, to set the second point
on the curve. The two points can be anywhere on the line, not necessarily at the ends.
• The chart shows an example of a customized curve 6(OD):5(SYS) that does not exist in the standard curve options. If the
outdoor temperature reaches 30ºF, the system target will be 145ºF.
• Remember that the Min Target and Max Target apply to all reset ratios including the customized reset ratio ones.
-- SET SYS TEMP.1 -
120 F
[
]
BACK SAVE
-- SET SYS TEMP.2 -
170 F
[
]
BACK SAVE
-- AT OD TEMP.1 ---
60 F
[ ]
BACK SAVE
-- AT OD TEMP.2 ---
0 F
[ ]
BACK SAVE
Outdoor Temperature (in °F)
70 60 50 40 20 30 0 -10 10 -20
120
140
130
150
160
170
180
100
110
W
ater
Temperature (in °F)
Custom Reset Ratio
Point1: System=120°F
Oudoor=60°F
Point2: System=170°F
Oudoor=0°F
Point1
Point2
Cust
omiz
ed R
eset R
atio
Max Target
Min Target
SET POINT (NOT ADJUSTABLE IN EMS MODE)
Adjustable -10ºF/-23ºC - 230ºF/110ºC Default: 140ºF/60ºC
Button: MENU/Set Point In Set Point or EMS 4-20mA
• The Set point is the temperature value the S8 will use to control the system.
• The S8 will add, subtract, or hold the stages of the heating or cooling units to maintain
the system temperature around the Set point.
----- SET POINT -----
70 F
[ ]
BACK SAVE
• The system can be expected to fluctuate around the set point. The amount of fluctuation depends on the System Settings and
Stage Settings.
• If an Outdoor Sensor was connected, pressing the SAVE button will switch to the Outdoor Cutoff setting option.
• If the EMS Mode was Enabled, the Set Point will be set by the EMS/BMS system and will be available to be only read.
• The range of Set Point in the EMS is set in the Startup menu at 4mA and 20mA.
• Any reading below the 2mA or above 22mA will indicate a "Shutdown by EMS" message on the Message Line.
OUTDOOR CUTOFF TEMPERATURE
Adjustable Off, 20ºF/-7ºC - 100ºF/38ºC, On Default: 70ºF/21ºC
Button: MENU/Set Point/Outdoor Cutoff in Set Point
Button: MENU/<Outdoor Reset>/Outdoor Cutoff in Reset
• In Outdoor Reset mode, Outdoor Cutoff will always exist. However, in Set Point mode,
if the outdoor sensor is installed, the Outdoor Cutoff screen will automatically appear
after the temperature Set Point has been selected.
-- OUTDOOR CUTOFF --
70 F
[ ]
BACK SAVE
• In Heating applications, when the outdoor temperature falls to the adjustable Outdoor Cutoff temperature, the S8 will control
and sequence the boiler stages to hold the calculated temperature.
• When the outdoor temperature rises to the Outdoor Cutoff plus a 2°F differential, the S8 will turn all boilers off. The System
relay and any other Pump or valve relays that were energized will remain energized for the Run-On delay.
• In Cooling applications, when the outdoor temperature rises to the adjustable Outdoor Cutoff temperature, the S8 will control
and sequence the cooling unit stages to hold the calculated temperature.
• The Outdoor Cutoff can be set to ON or OFF. In the ON position, the System Relay will run regardless of the Outdoor
temperature and the burner stages will be active to hold the calculated water temperature.
• In the OFF position, the system pump will always be off and all stages will be off as well.
TARGET OFFSET
Adjustable from 40ºF/22ºC - (-40ºF/-22ºC) Default: 0ºF/0ºC
Button: MENU/<Outdoor Reset>/Offset in Outdoor Reset only
• The Offset setting lets you adjust the starting points of the Reset Ratio curves. This
means that, regardless of the Outdoor temperature, or the Reset Ratio that has been
selected, when the Offset setting is changed, that change is directly added to or
subtracted from the calculated temperature. For example, if the Set Point temperature
was 130°F and the Offset was changed from 0° to 10° (an increase of 10°), then the Set
Point temperature would increase to 140°F.
-- TARGET OFFSET ---
+0 F
[
]
BACK SAVE