57
Installation & Operation Manual
8
Field wiring
(continued)
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 heat/
loop demands 1-3 (FIG. 8-3). If the boilers are to run
continuously, connect a jumper wire between the R and W
terminals for the heat/loop demand 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.
When the Member 1 boiler is programmed as an alternate
leader this allows the Member 1 boiler to automatically
assume control of the Cascade should it lose communications
with the Leader boiler. When programmed to YES, it is
recommended that the Member 1 boiler have its own set of
external sensors installed (such as the system supply sensor),
to maintain the same level of temperature control as with the
Leader boiler. Voltage signals (such as 0 - 10V system pump
speed input) can be connected to both boilers.
DO NOT connect the sensors connected
to the Leader boiler to the Member 1
boiler. The actual water temperatures
will be higher than expected, which could
lead to property damage, personal injury,
or death.
WARNING
When communication is re-established with the Leader
boiler, Member 1 will automatically relinquish control of the
Cascade to the Leader boiler.
