54
8
Field wiring
See the FTXL 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 fi ring 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 heat/loop demand 1 terminals.
Otherwise, the SMART SYSTEM control will be enabled by
the 0-10V signal.
2. Make sure the (-) terminal is connected to the (-) or
common output terminal of the external control, and the
(+) terminal is connected to the 0 - 10 VDC or (+) terminal
of the external control. Make sure that the (-) voltage is not
below ground.
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.
DHW recirculation sensor
The FTXL is able to control a DHW recirculation pump. To
operate this feature, a TST2032 temperature sensor must be
installed in the circulation loop return. Connect this sensor to
the DHW recirculation sensor terminals on the Low Voltage
Connection Board.
DHW recirculation pump
When the DHW recirculation sensor (as described above) is
connected, the FTXL SMART SYSTEM control will output
24VAC to control a DHW recirculation pump relay (fi eld
supplied). Connect the coil of the DHW recirculation pump
relay to the 24VAC recirculation pump relay coil terminals on
the Low Voltage Connection Board.
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 62 “Confi guration 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 6-5
through 6-10). 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 fi xed water temperature
set point that is programmed into the control.
If a Thermostat or Zone Control 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 communication
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.
Installation & Operation Manual
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.
