Install Instructions

Page 44
LAARS Heating Systems
Display
Boiler 1
Boiler 2
Boiler 3 Boiler 4
Controller
Burner
Figure 33. “Lead Lag” Operation in a System with Four Boilers. Note - the Displays on Boilers 2 thru
4 will display information pertaining only to that specic boiler.
Number of boilers
installed
Base load value
1 NA
2 65%
3 50%
4 35%
5 35%
6 35%
7 35%
8 35%
Table 18. - Base Load Settings
NOTE: If your units are Lead Lag congured, you
will nd it very useful to customize your Home
Display to show LL Operating Temp and LL
Setpoint Temp.
Please refer to Section 8.D to learn how
to customize your Home Display. Various
parameters can be displayed on the Home
Display to suit your needs.
reaction to the changes in demand.
See Figure 34 through Figure 35.
Control Settings for Lead Lag System - Part 1
1. Power up all of the boilers in the system.
2. In an installation with several boilers you can give
each boiler a di󰀨erent name. On each unit, go to
the screen for “System ID and Access,” and enter a
unique name.
How to get there: From the “Home” screen, press “I”
to go to “Info/Install” Choose “Advanced Setup,” then
go to “System Conguration,” then “System ID and
Access,” and select “Boiler Name.”
3. The controller in each of the boilers needs a unique
“Modbus address” so the Lead Lag Master can
communicate with it. All of the units come from the
factory with a Modbus address of “1,” so you will
need to change some of these addresses. The
unit operating as the Lead Lag Master should have
address “1,” and the other boilers should each have
unique Modbus address numbers.
CAUTION
You should set the Modbus addresses before you
connect the Modbus wiring. If the wiring is attached
before the Modbus addresses on the controls are
changed, there will be multiple controls with the
same address, and the system will not work.
WARNING
If the Modbus addresses are not assigned properly,
the system could fail to operate correctly, or it might
operate in an unsafe manner. This could lead to
property damage, personal injury or death.
How to get there: On each boiler: From the “Home”
screen, press “I” to go to “Info/Install.” screen. Choose
“Advanced Setup,” then select “System Conguration”.
Then select “System ID & Access,” and select “MB1
Modbus Address.” Change it to its new unique Modbus
address ( 1-8), then select “MB2 Modbus Address” and
change it to the same address as the changed “MB1
Modbus Address” DO NOT CHANGE THE MENU LINE
“ModBus Address”. It will automatically change when
you change the “MB1 Modbus Address”
4. The next job is to identify each boiler as a Lead Lag
Master or Follower.
• On the boiler that will be used as the Lead Lag
Master, identify the unit that will operate as the master
by turning on “Master Enable.”
How to get there: From the “Home” screen, press
“I” to go to “Info/Install.” Choose “Advanced Setup,”
then go to “Lead/ Lag Conguration.” Select “Lead
Lag Master Conguration.” On the line for “Master
Enable,” select “Enable.”
• On all of the boilers (including the Lead Lag Master),
8.N About Lead Lag Operation (continued)