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S8Ext
User Manual
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LAARS S8Ext User Manual

Laars Sequencing Controls
SYSTEM
DHW PUMP
INPUT RATINGS:
115VAC 60Hz, 12VA MAX
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
PWR
L N
1 2
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW PUMP
5
Stage A7Stage B9Stage C
11
13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
SYS=144F OD=35F
<AB
> DE GH JK
HI LO -- OFF
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 36
STAGE MENU
Stage E
Stage F
Stage G
Stage H
Stage A
Stage B
Stage C
Stage D
25
26
PRESS + -
37
38
PROVE
SYSTEM
TEMP
PROGRAM
RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
COMB. AIR
ENCLOSED
ENERGY
MANAGEMENT
EQUIPMENT
LISTED
99RA
C US
S8
SEQUENCING CONTROL
Sequencing
Model S8 and S8Ext
Output panel to Sequence
up to 24 individual
stages with lead-lag and
manual override capabilities
Document 4213
professional service technician, qualified 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, that is intended and certified as a high limit control, must be in the water heater/boiler control circuit.
Page 2 LAARS Heating Systems
Contents
S8 LAYOUT . . . . . . . . . . . . . . . . . . . . 3
S8 OVERVIEW. . . . . . . . . . . . . . . . . . . 4
UNDERSTANDING OPERATION CONCEPT
Reset Ratio/Outdoor Reset . . . . . . . . . . . . 5
Make Sure You Have the Right Control . . . . . . . 6
. . . 5
INITIAL SETUP . . . . . . . . . . . . . . . . . . 6
Selecting the System Features . . . . . . . . . . . 6
INSTALLATION . . . . . . . . . . . . . . . . . . 7
Mounting the Enclosure . . . . . . . . . . . . . . . 7
Install the Sensors . . . . . . . . . . . . . . . . . . 8
System Sensor Installation . . . . . . . . . . . . 8
Outdoor Sensor Installation . . . . . . . . . . . . 8
Wiring . . . . . . . . . . . . . . . . . . . . . . . . 9
Wiring the Power (Terminals 1, 2) . . . . . . . . . 9
Wiring the Sensors. . . . . . . . . . . . . . . . . 9
Wiring the Domestic Hot Water (DHW) Sensor
(Terminals 33, 34) . . . . . . . . . . . . . . . . . 10
Wiring the Shutdown (Terminals 35, 36) . . . . . . 10
Wiring the Setback (Terminals 35, 36) . . . . . . . 10
Wiring the Prove (Terminals 37, 38) . . . . . . . . 10
Wiring the System Output (Terminals 19, 20) . . . 10
Wiring the DHW Pump (Terminals 21, 22) . . . . . 11
Wiring the Comb. Air Damper (Terminals 23, 24) . 11
Wiring the Stage (Terminals 3, 17). . . . . . . . . 11
MENU SEQUENCE . . . . . . . . . . . . . . . 12
Connecting to S8EXT Panels and XSIG Interface 15
Startup Settings . . . . . . . . . . . . . . . . . . . 16
Program Change Settings . . . . . . . . . . . . . 16
Startup Sequence . . . . . . . . . . . . . . . . . 16
Control Mode . . . . . . . . . . . . . . . . . . . 16
Display Unit . . . . . . . . . . . . . . . . . . . . 16
Setting the 4mA and 20mA Set Points (Available in 4-
20mA EMS only) . . . . . . . . . . . . . . . . . . 16
Application . . . . . . . . . . . . . . . . . . . . . 17
DHW Piping (Available with Heating Only) . . . . 17
DHW Pump Output . . . . . . . . . . . . . . . . 17
Combustion Air Damper Output . . . . . . . . . . 17
Setback Mode . . . . . . . . . . . . . . . . . . . 17
Burner Type . . . . . . . . . . . . . . . . . . . . 18
Boiler Output . . . . . . . . . . . . . . . . . . . . 18
Total Boilers . . . . . . . . . . . . . . . . . . . . 18
Staging. . . . . . . . . . . . . . . . . . . . . . . 18
Sequence . . . . . . . . . . . . . . . . . . . . . 18
Control Logic. . . . . . . . . . . . . . . . . . . . 18
Sensor Fault . . . . . . . . . . . . . . . . . . . 194
Operating Settings . . . . . . . . . . . . . . . . . . 20
Program Change Settings . . . . . . . . . . . . . 20
Season. . . . . . . . . . . . . . . . . . . . . . . 20
Reset Ratio . . . . . . . . . . . . . . . . . . . . 20
Customized Reset Ratio . . . . . . . . . . . . . . 20
Set Point (Not Adjustable in EMS Mode) . . . . . 21
Outdoor Cutoff Temperature
Target Offset . . . . . . . . . . . . . . . . . . . . 21
Minimum Target . . . . . . . . . . . . . . . . . . 22
Maximum Target . . . . . . . . . . . . . . . . . . 22
Boiler Minimum Return. . . . . . . . . . . . . . . . 22
Minimum Return . . . . . . . . . . . . . . . . . . 22
Return Lag . . . . . . . . . . . . . . . . . . . . . 22
System Settings . . . . . . . . . . . . . . . . . . . 23
Program Change Settings . . . . . . . . . . . . . 23
Stage Settings . . . . . . . . . . . . . . . . . . . . 23
Reaction Time . . . . . . . . . . . . . . . . . . . 23
Purge Delay . . . . . . . . . . . . . . . . . . . . 23
Minimum Runtime . . . . . . . . . . . . . . . . . 23
Standby Delay . . . . . . . . . . . . . . . . . . . 23
Last Stage Hold . . . . . . . . . . . . . . . . . . 24
Throttle Range . . . . . . . . . . . . . . . . . . . 24
Lead Settings . . . . . . . . . . . . . . . . . . . . 24
Lead Boiler. . . . . . . . . . . . . . . . . . . . . 25
Rotate Mode . . . . . . . . . . . . . . . . . . . . 25
Setback Schedule . . . . . . . . . . . . . . . . . . 25
Setback . . . . . . . . . . . . . . . . . . . . . . 25
Boost. . . . . . . . . . . . . . . . . . . . . . . . 25
Boost Period . . . . . . . . . . . . . . . . . . . . 26
Day/Night Schedules . . . . . . . . . . . . . . . 26
Set Present Time . . . . . . . . . . . . . . . . . 26
DHW Settings . . . . . . . . . . . . . . . . . . . . 27
DHW Priority Timer (Available with Parallel DHW
Piping) . . . . . . . . . . . . . . . . . . . . . . . 27
DHW Set Point (Requires an Optional DHW
Temperature Sensor) . . . . . . . . . . . . . . . 27
DHW Differential . . . . . . . . . . . . . . . . . . 27
Pump, Valve, and Combustion Air Damper Operation 28
Run-On . . . . . . . . . . . . . . . . . . . . . . 28
Pump Exercise. . . . . . . . . . . . . . . . . . . 28
Maintenance . . . . . . . . . . . . . . . . . . . . . 28
System & Outdoor Sensor Trim . . . . . . . . . . 28
History . . . . . . . . . . . . . . . . . . . . . . . . 28
Configuration. . . . . . . . . . . . . . . . . . . . 29
Display . . . . . . . . . . . . . . . . . . . . . . . 29
Stage Settings . . . . . . . . . . . . . . . . . . . . 30
Mode . . . . . . . . . . . . . . . . . . . . . . . . 30
RunTime . . . . . . . . . . . . . . . . . . . . . . 30
. . . . . . . . . . . . 21
TROUBLESHOOTING. . . . . . . . . . . . . . 31
PIPING DIAGRAM . . . . . . . . . . . . . . . . 32
WIRING DIAGRAM . . . . . . . . . . . . . . . 33
SPECIFICATIONS
: . . . . . . . . . . . . . . . 34
LAARS Sequencing Controls S8 & S8EXT
Connect to Extension panels to
add additional stages or connect
to X-SIG Interface for
external 4-20mA set point.
When connecting Temperature Sensors, no
Polarity is observed. Prove terminals
must be connected for S8 to
operate stages.
Button function is presented on
bottom row of the display.
LEDs indicate
associated relay’s status
Program Switch to restrict access
to function changes. This Switch is
covered with Enclosure Wiring Cover.
System Output controls pumps, valves, or other system components. DHW Pump and Comb. Air relays are
controlled when configured.
Output Relays to manage the stages.
SYSTEM
DHW PUMP
INPUT RATINGS:
115VAC 60Hz, 12VA MAX
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
PWR
L N
1 2
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW
PUMP
5
Stage A7Stage B9Stage C
11 13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
SYS=144F OD=35F
<AB
> DE GH JK
HI LO -- OFF
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 36
STAGE MENU
Stage E
Stage F
Stage G
Stage H
Stage A
Stage B
Stage C
Stage D
25 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM
RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
COMB. AIR
ENCLOSED
ENERGY
MANAGEMENT
EQUIPMENT
LISTED
99RA
C US
S8
SEQUENCING CONTROL
S8 LAYOUT
Page 3
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.
LAARS Sequencing Controls S8 & S8EXT
Outdoor Temperature
Wate r Temperature
70 405060
130
120
110
100
Outdoor Temperature
Wate r T empe ratur e
70 405060
110
100
90
80
Outdoor Temperature
Wat er Temper ature
70 405060
150
140
130
120
1:4
With a 0° Offset, the ratio curves begin at 100° WaterTemperature.
With a -20° Offset, the ratio curves begin at 80° WaterTemperature.
With a +20° Offset, the ratio curves begin at 120° WaterTemperature.
1:4
1:4
1:1
1:1
1:1
4:1
4:1
4:1
90
100
+20 Offset
-20 Offset
Outdoor Temperature (in °F)
70 605040 20
30
0 -10
10 -20
100
120
110
130
140
150
160
180
170
190
200
210
220
1:3 1:2 1:1.5
1:1.25
1:1
1.25:1
1.5:1
2:1
3:1
4:1
Water Temperature (in °F)
Reset Ratio Curves
Reset Ratio is Presented as
Outdoor Temp. : Water Temp. Ratio
1:4
8:1
UNDERSTANDING OPERATION CONCEPT
The S8 has multiple operating modes that satisfy most hydronic systems. In heating, it can change the System Set Point based on outdoor temperature. Or, it can sequence stages to achieve an adjustable fixed Set Point in either heating or cooling.
In Outdoor Reset, the S8 controls a hot water heating system to provide a building with comfortable and even heat levels. The S8 varies the temperature of the circulating heating water in response to changes in the outdoor temperature. The heating water temperature is controlled through the sequencing of the stages.
The S8 also controls the system circulating pump with an adjustable Outdoor Cutoff. In heating, when the outdoor temperature is above Outdoor Cutoff, the pump is off and no heating water is circulated through the system. When the outdoor temperature drops below the Outdoor Cutoff, the system pump relay is activated and the heating water circulates through the system. The temperature of the heating water is controlled by the Reset Ratio, Water Offset, and changes with Outdoor temperature. In cooling applications, the outdoor cutoff turns off the cooling units and system pump when the outdoor temperature rises above the outdoor cutoff setting.
RESET RATIO/OUTDOOR RESET
When a building is being heated, heat escapes through the walls, doors, and windows to the colder outside air. The colder the outside temperature, the more heat escapes. If you can input heat into the building at the same rate that it is lost out of the building, then the building temperatures will remain constant. The Reset Ratio is an adjustment that lets you achieve this equilibrium between heat input and heat loss.
Page 5
The starting point for most systems is the 1.00 (OD):1.00 (SYS) (Outdoor Temperature : Heating Water Temperature) ratio. This means that for every degree the outdoor temperature drops, the temperature of the heating water will increase one degree. The starting point of the curves is adjustable, but comes factory selected at 70°F Outdoor Temp. and 100°F Water Temp. For example with a 1.00 (OD):1.00 (SYS) ratio, if the outdoor temperature is 50°F, this means the temperature has fallen 20° from the starting point of 70°F. Therefore, the heating water temperature will increase 20° to 120°F.
Each building has different heat loss characteristics. A very well insulated building will not lose much heat to the outside air, and may need a Reset Ratio of 2.00 (OD):1.00 (SYS) (Outdoor:Water). This means the outdoor temperature would have to drop 2 degrees to increase the water temperature 1 degree. On the other hand, a poorly insulated building with insufficient radiation may need a Reset Ratio of 1.00 (OD):2.00 (SYS). This means that for each degree the outdoor temperature dropped the water temperature will increase 2 degrees. The S8 has a full range of Reset Ratios to match any buildings heat loss characteristics.
A heating curve that relies not only on Outdoor temperature but also on type of radiation will improve heat comfort. The following are suggested initial settings for different types of radiation based on average building insulation and heat loss. The contractor can fine tune these adjustments based on the specific building need.
Type of Radiation in Building Reset Ratio Offset
Radiators (Steel & Cast Iron) 1.00 (OD) : 1.00 (SYS) 0˚F
Baseboard (Finned copper tube& Cast Iron) 1.00 (OD) : 1.00 (SYS) 0˚F
Radiant (High Mass/Concrete) 4.00 (OD) : 1.00 (SYS) -10˚F
Radiant (Low Mass/Joists) 2.00 (OD) : 1.00 (SYS) -10˚F
Fan Coils & Air Handlers
1.00 (OD) : 1.00 (SYS) 20˚F
WARNING
When controlling a non condensing boiler, minimum boiler water temperature must be set to boiler manufacturer specifications. In that case, system temperature must not go below such temperature.
Page 6 LAARS Heating Systems
MAKE SURE YOU HAVE THE RIGHT CONTROL
If you need the S8 to do additional tasks that either are not listed or do not know how to configure them, contact LAARS.
INITIAL SETUP
Setting an Initial Program will ease the configuration of the S8 and will give the opportunity to utilize many of the energy saving features and give more comfortable heat when needed.
The program should consist of the following:
• Selecting the features that your system can utilize
• Installation: Install the Control, switches and sensors
• Setting the System Startup
• Setting the System Settings
• Setting the Stages
• Adjusting Reset Ratio and Water Offset (In Reset Mode Only)
SELECTING THE SYSTEM FEATURES
The S8 has been designed with Hydronic heating and cooling as the primary purpose. With this in mind, many of the S8 features can be utilized to ease, enhance and improve your system performance. Some of these features are listed in this section.
HEATING OR COOLING WITH MULTIPLE OR SINGLE OUTPUT AT A TIME
• The S8 is equipped to control multiple multi-stage boilers with or without pumps or valves for heating application. As well, it can be configured for cooling with multiple stage chillers.
• That, combined with the capability of energizing only a single stage of a multi-stage cooling unit when in high demand, makes the S8 versatile for many industries.
OUTDOOR RESET, SET POINT, OR EXTERNAL 4-20MA SET POINT
• The S8 can control the System Temperature either by adjusting the calculated temperature according to the Outdoor Temperature (Outdoor Reset) or by maintaining an adjustable Set Point. The Outdoor Reset option uses an Outdoor Sensor (supplied with the control) and achieves better fuel savings in addition to better comfort.
• Using an optional X-SIG Interface (CA004200), the S8 can receive an external 4-20mA Set Point through EMS system.
PID OR OSS CONTROL LOGIC
• The S8 PID can be used for applications where system reaction will require a long period to achieve or measure the results. However, OSS, can be used for applications where the load changes frequently and the sequencing must match the load and its immediate change.
NUMBER OF STAGES
• The S8 can be configured to control up to eight stages. It can control up to 24 stages using a maximum of two S8 Extension Panels each with eight stages.
STAGE PUMPS OR VALVES
• The S8 can control muliple stages in addition to
CONTROL DHW PUMP AND COMBUSTION AIR DAMPER
• The control of the DHW is based on either a temperature sensor, can be purchased separately, on the DHW source or using a dry contact from an aquastat. The S8 provides multiple DHW Priority options to choose from based on the DHW piping. The Combustion Air Damper output can control the equipment while utilizing the Prove input to check the status on the Combustion Air Damper End Switch, System Pump Flow switch or any other checking devices before any stage is energized.
unit pumps, valves.
MONITOR BOILER RETURN
• The optional return line sensor, can be purchased separately, can be connected in heating applications to monitor and help protect the boilers from thermal shock and condensation caused by cool returns.
LAARS Sequencing Controls S8 & S8EXT
Mounting Base
Display Mounting Screws Wiring Cover Mounting Screws
Enclosure Display Module
Enclosure Wiring Cover Enclosure Base
Hole for optional
Padlock (not supplied)
AUTOMATIC ROTATION AMONG BOILERS
• Rotating the lead unit to be activated on a call for output promotes even wear on all units. The S8 has three modes of rotation: Manual, First-On-First-Off, or Timed Rotation. This option automatically rotates units every selected time period from one hour to every 41(999 hours) days.
SETBACK OR DAY/NIGHT SCHEDULING
Two Setback modes are available for the S8:
• The Day/Night Scheduling provides an adjustable time-based schedule for the Setback.
• The Setback mode uses an external signal to switch the operation of the S8 in and out of setback mode.
Page 7
INSTALLATION
Each of the S8 or S8EXT consists of three primary enclosure components.
• The Enclosure Display Module: contains the display, buttons, LEDs and electric wiring terminals. It has two screws to hold it to the base. A program configuration switch, used to adjust S8 settings, is placed above the terminals. This switch is enclosed with the enclosure wiring cover for security. Wiring terminals are of the plug-in type to ease installation and removal.
• The Enclosure Base: contains the holes to mount and hold the control against the wall or any flat surface. All other enclosure components mount on the base. The bottom section of the Enclosure Base contains the wiring chamber with knockouts on the bottom to easy installation.
• The Enclosure Wiring Cover: seals the wires from the external environment. It has two screws to hold it the base and a hole to secure a lock on the wiring enclosure. A plastic web that separates the wiring chamber into high and low volt sections has been provided.
MOUNTING THE ENCLOSURE
• Select a location near the equipment to be controlled.
• The surface should be flat, and be sufficiently wide and strong to hold the S8 or S8EXT.
• Keep the control away from extreme heat, cold, or humidity. Ambient operating temperature is from 20 to 120°F.
• Remove the Enclosure Wiring Cover from the control enclosure by removing the two bottom screws.
• Remove the Enclosure Display Module by removing the middle screws.
• Screw the Enclosure Base to the surface through the upper and lower mounting holes on the back of the enclosure.
• Replace the Enclosure Display Module and replace the middle screws.
• Do not replace the enclosure wiring cover until all wiring is done.
• When purchasing a padlock for the enclosure, the maximum shank diameter should not exceed ¼"
Page 8 LAARS Heating Systems
Immersion Well 3/8" ID 1/2" NPT
Heating System
Sensor
Common Supply Pipe
Sensor Probe
Immersion Heating System Sensor
Shield
Immersion Well 3/8" ID 1/2" NPT
Heating System
Sensor
Common Supply Pipe
Sensor Probe
Immersion Heating System Sensor
Shield
Common Supply Pipe
Sensor Probe
Strap-On Heating System Sensor
Shield
Pipe Insulation
10' Minimum
Outdoor Sensor
Low Voltage Sensor Wires
Sensor Clip
INSTALL THE SENSORS
SYSTEM SENSOR INSTALLATION
LOCATING THE SYSTEM SENSOR
• Put the System sensor approximately 10' feet past the last heating/cooling unit on the common supply header but before any major takeoffs.
• The sensor must be located where it sees the output of all the stages. If a unit is piped so that the sensor does not see its output, the S8 will not sequence the units correctly.
• Only use a Standard Brass Tube sensor (CA002400 or equivalent).
• The sensor wires can be extended up to 500' using a shielded 2-conductor cable (Belden #8760 or equivalent). Do not ground the shield at the sensor but at the panel using one of the terminals marked with an “O”.
• Do not run sensor wires in conduit with line voltage wiring.
IMMERSION HEATING SYSTEM SENSOR (HSS) INSTALLATION
• Install a 3/8"ID immersion well (CA002500 or equivalent).
• Insert the sensor probe of the supplied sensor into the well.
STRAP-ON HEATING SYSTEM SENSOR (HSS) INSTALLATION
• Strap the sensor to the pipe using metal clamps. Do not over tighten the clamp.
• Strap pipe insulation around the sensor and pipe.
If the System Sensor can not sense the correct system water temperature being supplied to the building, the S8 will not provide comfortable heat/cool levels. Be sure that it is located on a main supply pipe which can not easily be isolated from the system.
CAUTION
OUTDOOR SENSOR INSTALLATION
• Only use the Laars sensor included with the unit.
• Locate the sensor in the shade on the north side of the building. The sensor should never be in direct sunlight.
• Be sure the location is away from doors, windows, exhaust fans, vents, or other possible heat sources.
• The sensor should be mounted approximately 10' feet above ground level.
• Mount the sensor clip base to the outside of the building. Insert the sensor in the middle and snap close the clip on the sensor.
• The sensor wires can be extended up to 500' using shielded 2-conductor cable. Do not ground the shield at the sensor but at the control using the terminal marked with an “O”.
• Do not run sensor wires in conduit with line voltage wiring.
The S8 is an operating control only. All equipment must have all safety and limit controls required by code. It is the responsibility of the installer to verify that all the safety and limits are working properly before the S8 is installed.
Determining the proper location for the Outdoor Sensor is very important. The S8 will base its operation on the outdoor temperature information it receives from this location. If the sensor is in the sun, or covered with ice, its reading will be different from the actual Outdoor temperature (OD).
WARNING
CAUTION
LAARS Sequencing Controls S8 & S8EXT
Line
Neutral
DHW
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
PWR
L N
1 2
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW
PUMP
5
Stage A7Stage B9Stage C
11 13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
PWR
L N
1 2
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW PUMP
5
Stage A7Stage B9Stage C
11 13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
Lo Hi
Unit1
Stages
Lo Hi
Unit2
Stages
Sensor Shiled
SENSORS MUST BE GOLD SERIES
RS485
OUTDOOR
TEMP
27 29
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
26
37
38
PROVE
SYSTEM
TEMP
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Outdoor Sensor
Prove
Dry Contact
Sensor Shiled
System Sensor
Sensor Shiled
Return Sensor
Shutdown
Dry Contact
Sensor Shiled
DHW Sensor
SENSORS MUST BE GOLD SERIES
RS485
OUTDOOR
TEMP
27 29
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
26
37
38
PROVE
SYSTEM
TEMP
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
SENSORS MUST BE GOLD SERIES
RS485
OUTDOOR
TEMP
27 29
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
26
PRESS + -
37
38
PROVE
SYSTEM
TEMP
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
Sensor Shiled
Outdoor Sensor
Prove
Dry Contact
Sensor Shiled
DHW Sensor
RS485
OUTDOOR
TEMP
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
37
38
PROVE
SENSORS MUST BE GOLD SERIES
RS485
OUTDOOR
TEMP
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
37
38
PROVE
TEMP
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
Sensor Shiled
RS485
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
37
38
PROVE
Outdoor Sensor
Prove
Dry Contact
Sensor Shiled
Sensor Shiled
Return Sensor
Shutdown
Dry Contact
Sensor Shiled
DHW Sensor
RS485
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
37
38
PROVE
RS485
TEMP
31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
37
38
PROVE
Setback
Dry Contact
WIRING
WIRING THE POWER (TERMINALS 1, 2)
• Bring the 120VAC 60Hz power wires through the bottom Knockout of the enclosure.
• Class 1 voltages must enter the enclosure through a different opening from any Class 2 voltage wiring.
• Connect the hot line to terminal marked L.
• Connect the neutral line to the terminal marked N.
WARNING
Class 1 voltages must enter the enclosure through a different opening from any Class 2 voltage wiring. Laars recommends installing a surge suppressor on the power source to the S8.
Page 9
Connect the shield at the control terminal end and cut the shield wire at the sensor end.
WIRING THE SENSORS
SYSTEM TEMPERATURE SENSOR WIRING (TERMINALS 27, 28)
• A S8 must be connected to a temperature sensor located in the common header.
• The S8 is designed to be connected to a temperature sensor (CA002400 or equivalent) for immersion in a
3/8ID well (CA002500 or equivalent). Contact the factory for additional temperature sensor options.
• Temperature sensor wires can be extended up to 500’ by splicing shielded 2-
conductor cable (Belden #8760 or equivalent).
• Temperature sensors have no polarity. Connect the two wires from the
sensor to the S8 terminals marked SYSTEM TEMP 27, 28.
• Connect the sensor shield to the circled terminal 28 with one of the sensor wires.
OUTDOOR SENSOR WIRING (TERMINALS 29, 30)
• When Outdoor Reset is selected, the S8 will vary the system Set Point based on outdoor temperature.
• Whether in Set Point or Outdoor Reset modes, the outdoor sensor can be used as an Outdoor Cutoff. In
heating, the S8 will disable all Boilers when the outdoor temperature is above the adjustable Outdoor Cutoff temperature. However, in cooling it will disable the units when the outdoor temperature is below the Outdoor Cutoff. This feature will automatically be activated when an outdoor sensor is connected.
• For an outdoor sensor use a Laars outdoor sensor (CA002400 or equivalent).
• The sensor wires can be extended up to 500’ using shielded 2-conductor cable (Belden #8760 or equivalent).
• Temperature sensors have no polarity. Connect the wires from the outdoor
• Connect the shield to the circled terminal 30 with one of the sensor wires.
sensor to the S8 terminals marked OUTDOOR TEMP - 29, 30.
WARNING
RETURN SENSOR WIRING (TERMINALS 31, 32) OPTIONAL (AVAILABLE IN HEATING ONLY)
• If the Return Sensor is connected, must be purchased separately, the S8 will recognize
it and alternate its temperature on the display with the Target temperature. If the Return is below the Minimum Return, the S8 will sequence stages based on the Return Sensor, Minimum Return, Calculated Target, and the actual System Temperature.
• The Return on the S8 is designed to be connected to a temperature sensor that can be purchased
separately (CA002400 or equivalent) for immersion in a 3/8ID well (CA002500 or equivalent).
• The sensor wires can be extended up to 500’ using shielded 2-conductor cable (Belden #8760 or equivalent).
• Temperature sensors have no polarity. Connect the wires from the outdoor
sensor to the S8 terminals marked OUTDOOR TEMP - 31, 32.
• Connect the shield to the circled terminal 32 with one of the sensor wires.
Page 10 LAARS Heating Systems
Sensor Shiled
Prove
Dry Contact
Sensor Shiled
DHW Sensor
RS485
DHW
33
SHUTDOWN
/SETBACK
35
37 38
PROVE
RS485
DHW
33
SHUTDOWN
/SETBACK
35
37 38
PROVE
Setback
Dry Contact
RS485
SHUTDOWN
/SETBACK
35
37 38
PROVE
Prove
Dry Contact
Shutdown
Dry Contact
Sensor Shiled
DHW Sensor
RS485
SHUTDOWN
/SETBACK
35
37 38
PROVE
RS485
DHW
SHUTDOWN
/SETBACK
35
37 38
PROVE
Setback
Dry Contact
RS485
SHUTDOWN
/SETBACK
35
37 38
PROVE
Setback
Dry Contact
Prove
Dry Contact
RS485
37 38
PROVE
RS485
37 38
PROVE
Setback
Dry Contact
Sensor Shiled
SENSORS MUST BE GOLD SERIES
SYSTEM
DHW
PUMP
17
RS485
19
Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Outdoor Sensor
Prove
Dry Contact
Sensor Shiled
DHW Sensor
System
Pump
DHW
Pump
Comb.
SENSORS MUST BE GOLD SERIES
SYSTEM
DHW PUMP
17
RS485
19
Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
SENSORS MUST BE GOLD SERIES
SYSTEM
DHW PUMP
17
RS485
19
Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
WIRING THE DOMESTIC HOT WATER (DHW) SENSOR (TERMINALS 33, 34)
• DHW can be used to raise system Set Point to 200°F or Maximum Target, whichever is lower. DHW Piping
• DHW Call terminals can be either a dry contact N.O. or a temperature sensor that can be purchased separately
• If dry contact, wire an aquastat or other controls to provide closure on the DHW terminals.
• The sensor wires can be extended up to 500’ using shielded 2-conductor cable (Belden #8760 or equivalent).
• Temperature sensors have no polarity. Connect the wires from the DHW sensor to the S8 terminals marked
• Connect the shield to the circled terminal 34 with one of the sensor wires.
WIRING THE SHUTDOWN (TERMINALS 35, 36)
• This feature will only be available when Day/Night Schedules are selected as the Setback Mode option from the
• This feature can be used whenever it is desirable to turn off the S8 stage outputs from a remote location or
• When the Shutdown feature is enabled by closing a dry contact, all active stages will immediately turn off. The
• The Shutdown signal must be a dry contact only. No voltage can be placed across the
• Bring the two wires from the dry contact to the terminals marked SHUTDOWN- 35,36.
WIRING THE SETBACK (TERMINALS 35, 36)
• This feature can be used whenever it is desirable to switch the S8 to operate in Setback from a remote location
• When the Setback is enabled by closing a dry contact, the Target will change by the Setback value. That is, in
• The Setback signal must be a dry contact only. No voltage can be placed across the SETBACK terminals.
• Bring the two wires from the dry contact to the terminals marked SETBACK- 35,36.
WIRING THE PROVE (TERMINALS 37, 38)
• The Prove feature is provided to check system component operation before energizing the stages. It can be
• If the Comb. Air Damper Output option was not activated, the PROVE input can be used to check on the
• If the PROVE input is open on a call, the S8 will enable only the System Output. All stage outputs will be off
• A factory-installed jumper provides the System Prove signal. Do not remove the jumper unless it will be
• Bring the two wires from the dry contact to the terminals marked PROVE - 37, 38. No voltage can be placed
WIRING THE SYSTEM OUTPUT (TERMINALS 19, 20)
System Output Operation in Set Point Mode
• In Heating, the SYS output relay will energize whenever the outdoor temperature drops below the Outdoor
• No stage outputs will be activated until the Prove input is shorted. If a Prove is not required, the factory-
concept must be selected in the Startup Menu to determine the DHW Priority options.
(CA002400 or equivalent) for immersion in a 3/8ID well (CA002500 or equivalent).
DHW - 33, 34.
Startup menu.
another controller (i.e. EMS input).
System and Comb. Air, and unit pumps' or valves' relays will remain energized for the Run-On delay period and then turn off.
SHUTDOWN terminals.
(i.e. EMS input or external time clock). It will only be available when External Signal are selected as the Setback Mode option from the Startup menu.
Heating, the Target will be reduced by the Setback value. On the other hand, in Cooling, the Setback will be added to the Target Set Point.
used to check on the Combustion Air Damper by connecting it to the end switch of the damper. In this case, the Comb. Air Output option must be activated from the Startup Menu.
System Output. A typical use of this feature is to check for system pump flow before energizing any stage.
when the PROVE input is open.
replaced by a System Prove signal.
across the PROVE terminals
The PROVE input cannot be used as a safety limit. All equipment must have its own certified limit and safety controls as required by local codes. No boiler stage will start unless Prove terminals are shorted. DO NOT remove
WARNING
the PROVE jumper supplied unless replacing it with a Prove signal.
Cutoff or whenever a stage output is active. If no outdoor sensor is connected and the last boiler relay has de­energized, the SYS relay will remain energized for a period set by the Run-On.
installed jumper should remain connected.
LAARS Sequencing Controls S8 & S8EXT
DHW
Pump
SENSORS MUST BE GOLD SERIES
DHW
PUMP
RS485
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS + -
37 38
PROVE
SYSTEM
TEMP
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
SENSORS MUST BE GOLD SERIES
SYSTEM
DHW
PUMP
RS485
19
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
Sensor Shiled
SENSORS MUST BE GOLD SERIES
RS485
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Outdoor Sensor
Prove
Dry Contact
Shutdown
Dry Contact
Sensor Shiled
DHW Sensor
Comb.
Air
Damper
SENSORS MUST BE GOLD SERIES
RS485
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
PRESS + -
37 38
PROVE
SYSTEM
TEMP
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
SENSORS MUST BE GOLD SERIES
DHW
RS485
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW
PUMP
5
Stage A7Stage B9Stage C
11 13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS + -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
Lo Hi
Unit1
Stages
Lo Hi
Unit2
Stages
Sensor Shiled
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW
PUMP
5
Stage A7Stage B9Stage C
11 13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS
+ -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Outdoor Sensor
Prove
Dry Contact
Sensor Shiled
System Sensor
Sensor Shiled
Return Sensor
Shutdown
Dry Contact
Sensor Shiled
DHW Sensor
Lo Hi
Unit1
Stages
Unit1
Pump
Lo Hi
Unit2
Stages
Unit2
Pump
System
Pump
DHW
Pump
Comb.
Air
Damper
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW PUMP
5
Stage A7Stage B9Stage C
11 13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS + -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Use Copper Conductors Only.
CAUTION:
Risk of Electric Shock.
SENSORS MUST BE GOLD SERIES
SYSTEM
3
DHW
PUMP
5
Stage A7Stage B9Stage C
11 13
Stage E15Stage F
17
Stage D
6 8 10 12 14
16 18
RS485
4
Stage G19Stage H
21
OUTDOOR
TEMP
27 29 31
DHW
33
SHUTDOWN
/SETBACK
35
RETURN
TEMP
20 22 28 30 32 34 3625 26
PRESS + -
37 38
PROVE
SYSTEM
TEMP
PROGRAM RUN
OUTPUT RATING: 6 AMP RESISTIVE, 1 AMP PILOT DUTY PER OUTPUT AT 120VAC.
23 24
COMB.
AIR
DO NOT APPLY ANY VOLTAGE TO INPUT TERMINALS
Setback
Dry Contact
Lo Hi
Unit1
Stages
Lo Hi
Unit2
Stages
• In Cooling applications, the system relay will energize when the outdoor temperature is above the Outdoor Cutoff setting.
• A typical use of the SYS output is to activate a system pump starter. The pump can run whenever there is a call for heat/cool.
When stages are no longer required, the pump will stay active for an adjustable Run-On delay.
System Output Operation in Reset Mode
• The SYS output relay will energize whenever the outdoor temperature is below the Outdoor Cutoff.
• The SYS will remain constantly energized while the outdoor temperature is below the Outdoor Cutoff.
• When the outdoor temperature rises 2°F above the Outdoor Cutoff, the SYS output will remain energized for the period set by
the System Run-On.
• The SYS output has one Normally Open (N.O.) relay that acts as a dry contact only. It does not source any power.
• Class 1 voltages must enter the enclosure through a different opening from any Class 2 voltage wiring.
WIRING THE DHW PUMP (TERMINALS 21, 22)
The S8 can control the DHW Pump when the DHW Pump Output option is activated in the Startup Menu..
• The S8 will energize the DHW Pump whenever there is a call for DHW using a dry contact or when the DHW
temp falls below the DHW Set Point and DHW Differential.
• The DHW Pump output is Normally Open (N.O.) dry contact only. It does not source any power.
• Class 1 voltages must enter the enclosure through a different opening from any Class 2 voltage wiring.
WIRING THE COMBUSTION AIR DAMPER (TERMINALS 23, 24)
The S8 can control the Combustion Air Damper when the Comb. Air Output option is activated in the Startup Menu.
• The S8 will energize the Combustion Air Damper relay whenever there is a call to energize any of the unit
stages.
• The Comb. Air output has one Normally Open (N.O.) dry contact relay. It does not source any power.
• Class 1 voltages must enter the enclosure through a different opening from any Class 2 voltage wiring.
• In this scenario, the Prove input will be used to check on the Combustion Air Damper status.
Page 11
WIRING THE STAGES (TERMINALS 3 TO 17)
The S8 can be configured to operate the stages of the heating or cooling units. Moreover, it can be configured to operate the unit pumps or valves in addition to the unit stages.
• The N.O. contacts are dry contacts only. They do not source any voltage.
• Wire the N.O. relay contacts in series with the unit’s limit circuit.
• Class 1 voltages must enter the enclosure through a different opening from any Class 2 voltage
wiring.
WIRING THE STAGE OUTPUTS
• Each Stage output (A through H) has one Normally Open (N.O.) relay contact.
• When wiring several multi-stage units, start with the lower stage of the first unit and wire it to
Output A, followed by the higher stage of the same unit and wire it to Stage B.
WIRING THE PUMP OR VALVE OUTPUTS
• If the S8 is configured to operate Stage Pumps or Valves, then, wire them using the stage after the
highest stage for that unit. That is, the low stage for the first unit must be connected to A and the higher stage of the same unit must be connected to Stage B. The Valve or Pump for the same unit must be connected to Stage C.
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