30
5
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 Outdoor 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. 5-3).
Boiler management system
The United States Energy Policy and Conservation Act
requires residential heating boilers with inputs less than
300,000 Btu/hr be equipped with a control that automatically
adjusts boiler water temperature in relation to heat demand.
An external control may be connected to control the firing
rate or the set point of the boiler provided that either an
external energy management system is installed that reduces
the boiler water temperature as the heating load decreases,
the boiler is not used for any space heating, or the boiler is
part of a modular or multiple boiler system having a total
input of 300,000 Btu/hr or greater.
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 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 0 - 10 Vdc terminal is connected to the 0 - 10 Vdc
terminal of the external control. Make sure 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.
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 38 “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 3-5,
3-7, and 3-9). The system supply sensor should be wired to the
Low Voltage Connection Board at the terminals marked for
the system sensor (see FIG. 5-3). The Leader control will use
the water temperature at the system supply sensor to control
the operation of the Cascade.
The outdoor air sensor should be wired to the Low Voltage
Connection Board at the terminals marked for the outdoor air
sensor (FIG. 5-3). The Leader control will calculate the water
temperature set point based on the programmed reset curve
parameters.
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. 5-3). 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. 5-3). 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.
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. Remove the jumper wire from these terminals, and
connect these terminals to the normally open contacts on
the flow switch (FIG. 5-3).
Outdoor Knight Boiler Installation & Operation Manual
