Multiple Boilers - RBI IEW-199 Installation And Operation Instructions Manual

H. MULTIPLE BOILERS
1. Infinite Energy boiler controls can operate together to
control up to 16 boilers for one Domestic hot water
demand (single or multiple tanks). Only one DHW
Tank Sensor is required to provide this operation.
2. Overview:
a. Master Boiler: In a multiple boiler system, a boiler
designated as the "Master" boiler controls the
function of the boiler system.
• The domestic water sensor is attached to the
master boiler to monitor the DHW system
temperature.
• The master boiler determines which boiler
operates first and when to bring on additional
boilers.
• The master boiler determines the input rate at
which to operate individual boilers.
• Shuts down all boilers in the system if the
LWCO contacts are opened.
b. Dependent Boilers: The "Dependent" boilers
operate at the input rate and/or temperature that
the master boiler specifies.
• Dependent boilers maintain all of their own
safety parameters such as high temperature
limiting, vent temperature limiting and freeze
protection.
• Dependent boilers control their own general
circulator that is energized whenever there is a
heat call from the master boiler.
• Dependent boilers will shut down if its LWCO
contacts are opened.
3. System Piping & Wiring:
a. Figure 8.8 shows multiple DHW Supply Boilers
which circulates with a single or multiple tanks.
• Each circulator is wired to the "General" pump
terminals in the boiler which it serves.
• The "Master" boiler is connected to either a
tank temperature sensor or to the tank
thermostat.
4. Setting up Multiple Boiler Operation:
a. Setting the Boiler Address:
• Press the "Menu" and "Select" keys
simultaneously for 5 seconds to enter the
Installer Menu.
• Use the " " key to scroll down to "Cascade
M
Settings" on the menu.
• Pressing "Select" will cause the Boiler Address
value to blink. Use the "
change the value.
• The master boiler is to be designated as Boiler
Address: 1.
• All dependent boilers must have sequential
boiler address settings as shown on the
following table.
BOILER CONTROL: INTERNAL WIRING & OPERATION
Table 8.7: Cascade Addresses and Sensor Functions
Operation
Stand-alone
Boiler
Boiler #1
Master
Boiler #2
Dependent
Boiler #3
Dependent
Boiler #16
Dependent
" and " L " keys to
M
Boiler Cascade System
Address Sensor
Not
0
Active
1 Active
Not
2
Active
Not
3
Active
Not
16
Active
• Once a boiler is designated as a dependent
boiler, the display will show the individual
boiler supply temperature and its status.
• The master boiler will display the DHW tank
temperature and the overall status of the
cascade system.
• By pressing the " L " and "
operator can view the supply temperature and
status of the master boiler itself.
b. Connecting the Cascade Links:
• Remove the User Interface Display from the
Master boiler only.
• Slide the master switch lever toward the center
of the printed circuit board. The Master Switch
Lever is not marked with "ON" or "OFF" but
the switch is in the "ON" position when it is
moved to the left as viewed from the back of
the display. The position is shown in Figure
8.9.
• Re-attach the User Interface Display.
• Connect wires from terminals #11 &#12
between all boilers in the cascade system. See
Figure 8.10.
2. Cascade Operation:
a. When a call for Domestic Hot Water (DHW) is
present, the master boiler chooses which boiler
will lead based on the Cascade Rotation Interval.
b. Before starting the lead boiler, the master control
will first check to assure that the tank temperature
is lower than the system setpoint + the stop boiler
differential.
c. After the first boiler starts, if the call is still present
after the "Start Delay Time" selected from the
Cascade Menu, the next boiler will start.
d. Another boiler will start after the "Start Delay
Time" is reached again until all the boilers in the
system are running or until the demand is
satisfied.
e. The default value for the "Start Delay Time" is 10
seconds. Appendix C shows the Cascade Menu
and the range for this parameter.
f. Once all boilers are running, the master boiler
modulates the boilers together until the tank
temperature approaches the setpoint.
Outdoor DHW
Sensor Sensor
Active Active
Active Active
Not Not
Active Active
Not Not
Active Active
Not Not
Active Active
" keys the
M
35