Installation & Operation Manual
50
8
Field wiring
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 water
heater is responding to a call for heat.
Alarm contacts
The SMART SYSTEM control closes another set of contacts
whenever the water heater 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 water heater is
down.
Wiring of the cascade
When wiring the water heaters for Cascade operation, select
one water heater as the Leader water heater. The remaining
water heaters will be designated as Members. See page 58
“Configuration of the Cascade” for a detailed explanation
of this procedure.
Connect the tank sensor to the Leader water heater. For the
Cascade system to work properly the tank sensor must be
installed. The tank sensor should be wired to the low voltage
connection board at the terminals marked for the tank
sensor (see FIG. 8-3). The Leader control will use the water
temperature at the tank sensor to control the operation of
the Cascade.
Communication between the Leader water heater and the
Member water heaters 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 water heaters are on the
Cascade, daisy chain the wiring from the Cascade terminals
on the second water heater to the Cascade terminals on the
third water heater, then from the third to the forth, and so
on. The connections between heaters can be made in any
order, regardless of the addresses of the water heaters. Try
to keep each cable as short as possible.
