Lochinvar KBII-I-O REV C 81 - 286 - Manual (Page 52)

52
Installation & Operation Manual
8
Field wiring
System supply sensor
1. By installing the system supply sensor into the supply of
the primary loop, the temperature of the primary supply
can be controlled. The SMART SYSTEM control
automatically detects the presence of this sensor, and
controls the boiler firing rate to maintain the system
supply temperature to the set point (if the outlet sensor
control is currently selected). If it is desired to control the
system return temperature, then program the SMART
SYSTEM control to use the inlet sensor as the controlling
sensor. See the Knight Boiler Service Manual for
instructions on how to use the inlet sensor as the
controlling sensor. When the inlet sensor is programmed
as the controlling sensor, it is vital that the SYSTEM
SUPPLY sensor be installed. DO NOT INSTALL THE
SYSTEM SUPPLY SENSOR INTO THE SYSTEM
RETURN.
2. The TST2032 sensor provided with the boiler must be
used for the system sensor.
3. Connect these terminals to the system supply sensor
(FIG. 8-3).
Boiler management system
1. An external control may be connected to control either
the firing rate or the set point of the boiler. If the external
control uses a set of contacts to enable the boiler, connect
the contacts to the Room Thermostat 1 terminals.
Otherwise, the SMART SYSTEM control will be enabled
by the 0-10V signal.
2. Make sure the ground terminal is connected to the
ground output terminal of the external control, and the
0 - 10 vdc terminal is connected to the 0 - 10 vdc terminal
of the external control.
Runtime contacts
The SMART SYSTEM control closes a set of dry contacts
whenever the burner is running. This is typically used by
Building Management Systems to verify that the boiler is
responding to a call for heat.
Alarm contacts
The SMART SYSTEM control closes another set of contacts
whenever the boiler is locked out or the power is turned off.
This can be used to turn on an alarm, or signal a Building
Management System that the boiler is down.
Wiring of the cascade
When wiring the boilers for Cascade operation, select one
boiler as the Leader boiler. The remaining boilers will be
designated as Members. See page 60 “Configuration of the
Cascade” for a detailed explanation of this procedure.
Connect the system supply sensor and outdoor air sensor (if
used) to the Leader boiler. For the Cascade system to work
properly the system supply sensor must be installed. The
location of the system supply sensor should be downstream of
the boiler connections in the main system loop (FIG.’s 6-4,
6-6, and 6-8). The system supply sensor should be wired to the
Low Voltage Connection Board at the terminals marked for
the system sensor (see FIG. 8-3). The Leader control will use
the water temperature at the system supply sensor to control
the operation of the Cascade.
If outdoor air reset is desired, the outdoor air sensor should be
wired to the Low Voltage Connection Board at the terminals
marked for the outdoor air sensor (FIG. 8-3). If the outdoor
air sensor is connected, the Leader control will calculate the
water temperature set point based on the programmed reset
curve parameters. If the outdoor air sensor is not connected,
the Leader control will maintain the fixed water temperature
set point that is programmed into the control.
If a Thermostat, Zone Control enable output, or Building
Management System enable output is available, it should be
wired to the Low Voltage Connection Board on the Leader
boiler at the terminals marked for one of the Room
Thermostats 1-3 (FIG. 8-3). If the boilers are to run
continuously, connect a jumper wire between the R and W
terminals for the Thermostat input. This will initiate a call for
heat on the Cascade.
Communication between the Leader boiler and the Member
boilers is accomplished by using shielded, 2-wire twisted pair
communication cable. Connect one of the twisted pair wires
to Cascade terminal A on each of the Low Voltage Connection
boards, and the other wire of the twisted pair to Cascade
terminal B on each of the Low Voltage Connection Boards.
Connect the shield wires to one of the shield terminals on the
Low Voltage Connection Boards (FIG. 8-3). If more than two
boilers are on the Cascade, daisy chain the wiring from the
Cascade terminals on the second boiler to the Cascade
terminals on the third boiler, then from the third to the forth,
and so on. The connections between boilers can be made in
any order, regardless of the addresses of the boilers. Try to
keep each cable as short as possible.
ModBus
When the optional ModBus interface module is installed, the
RS-485 ModBus cable is connected to these terminals. Use
shielded, 2-wire twisted pair cable. If desired, the shield can
be connected to ground by installing a jumper wire between
terminals 1 and 3 on connector X5 on the optional ModBus
interface module.
Flow switch
1. A flow switch is used to guarantee flow through the boiler
before allowing it to fire. The flow switch must be
installed at the boiler outlet.
2. Connect these terminals to the normally open contacts on
the flow switch (FIG. 8-3).