LAARS S8Ext - Installation Manual - Manual (Page 4)

Page 4 LAARS Heating Systems
S8 OVERVIEW
SEQUENCES UP TO 8 STAGES WITH PUMPS OR VALVES.
The S8 is the perfect control whenever multiple boiler or chiller stages are required for hydronic heating or cooling applications. The S8
controls the stages and their pumps or valves to maintain a precise system set point.
PID OR OVER-SIZED-SYSTEM (OSS) LOGIC
The S8’s control algorithm allows it to look at the rate of change in the system. If the load is changing quickly, the S8 can be set to OSS
sequencing where it will react based on load changes. If the system fluctuations are minimal as in heating applications, the S8 will make
slow and gradual output adjustments. Therefore, the S8 adapts to specific system requirements and minimizes fluctuations around the
set point.
DIGITAL DISPLAY OF ALL SYSTEM SETTINGS
The S8’s alphanumeric digital display names each system parameter in simple English and shows its precise value. The easy to follow
menu system allows users to quickly make changes to any system setting without having to learn any specialized codes or keyboard
commands.
AUTOMATIC ROTATION AMONG STAGES
Rotating the first stage to be activated on a call for output promotes even wear on each unit. The S8 has three modes of rotation: Manual,
FOFO, or Time. The Time rotates the lead stage every selected time period from every hour to every 41 days.
OUTDOOR RESET WITH CUSTOMIZABLE CURVE
The S8 has a hydronic outdoor temperature reset function. This allows the S8 to change the set point based on outdoor temperature.
Furthermore, a customizable outdoor reset curve has been incorporated for unique applications where standard reset ratios will not satisfy.
In addition, the following settings have been added to help fine tune all reset operation; Offset, Minimum, and Maximum Targets and
Night Setback Schedule or Setback using an External Signal.
STANDBY UNIT OPTION
Any of the S8 heating or cooling units can be configured as a Standby with an adjustable Standby delay. Assigning a specific unit to
work in standby mode will remove it from the rotation. In this mode, the unit will be used for backup in large demand periods where
the primary units will not suffice.
SYSTEM AND COMBUSTION AIR DAMPER OUTPUTS WITH PROVE INPUT
These outputs work with the control logic to operate a primary system pump and a combustion air damper. In addition, a System Prove
input can be wired in to check the status of either of the components activated by the outputs before stages can be activated.
NORMAL OR PARALLEL (LO/LO/HI/HI) SEQUENCING
The S8 can sequence heating or cooling units as needed. For heating systems where higher efficiency is achieved using lower firing
stages, the S8 offers the Parallel Sequencing option. It will sequence all the low firing stages first before bringing the rest of the stages
on. For other types of heating and cooling units, using the Normal Sequencing option will bring the lower operating stage followed by
the higher one of the lead unit. Then, will do the same with the lag unit.
MULTIPLE OR SINGLE STAGING
Unlike many boilers/water heaters where, to fire a multi-stage boiler both low and high stage relays must be energized, some of the
available cooling units require that the operation of the higher stages turn off the lower operating stages. This can be achieved by selecting
Single from the Startup Staging menu.
ADD UP TO 16 STAGES
As a stand-alone, the S8 is designed to control eight stages. However, it has the capability of expanding its control to two extension
panels each with eight stages. Thus, the S8 can control a total of up to 24 stages.
MONITOR SYSTEM RETURN TEMPERATURE
Using a smart algorithm, the S8 can monitor boiler return temperature using an optional return sensor mounted on the return line. Then,
sequence the boilers to raise above an adjustable Minimum Return.
DHW PUMP CONTROL WITH MULTIPLE PRIORITY OPTIONS
Having a DHW input either as a dry contact to be used with an external aquastat or as a temperature sensor that can be ordered separately,
the S8 can control a DHW pump using its built-in output relay. The user will have different priority options that varies based on the
DHW piping design.