53
Installation & Operation Manual
8
Field wiring
(continued)
Thermostat
1. Connect the room thermostat or end switch (isolated
contact only) to heat/loop demand 1, 2, or 3, as shown
in FIG. 8-4.
2. Install the thermostat on the inside wall away from
influences of drafts, hot or cold water pipes, lighting
fixtures, television, sunlight, or fireplaces.
3. Thermostat anticipator (if applicable):
a.
If connected directly to boiler, set for 0.1 amps.
b. If connected to relays or other devices, set to
match total electrical power requirements of
connected devices. See device manufacturers’
specifications and thermostat instructions for
details.
Outdoor temperature sensor
1. Mount the sensor on an exterior wall, shielded from
direct sunlight or flow of heat or cooling from other
sources.
2. Route sensor wires through a knockout in the bottom
front right side of the boiler (see FIG. 8-3).
3. Connect outdoor temperature sensor (FIG. 8-4) to the
outdoor sensor terminals on the connection board to
enable outdoor reset operation of the Knight wall mount
boiler. Residential boilers with inputs less than 300,000
Btu/hr must use either outdoor reset or an external
energy management system. If fixed temperature
operation is required on larger boiler systems, do not
install an outdoor sensor.
DHW thermostat
1. Connect storage indirect water heater (DHW) thermostat
(FIG. 8-4) to the DHW thermostat terminals on the
connection board. If a tank sensor is connected (see
DHW Tank Sensor below) the tank thermostat is ignored.
Louver relay
1. If louvers need to operate when the boiler fires, they can
be controlled by this output. Connect these terminals to
a 24 vac relay coil, which is wired to operate the louvers
(FIG. 8-4).
Louver proving switch
1. When the operation of the louvers needs to be verified
before the boiler fires, remove the jumper wire from these
terminals and connect them to the normally open contacts
on its proving switch (FIG. 8-4).
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. 8-4).
DHW tank sensor
1. By installing a tank sensor, the SMART SYSTEM control
can perform the tank thermostat function. The SMART
SYSTEM control automatically detects the presence of
this sensor and generates a DHW call for heat when
the tank temperature drops 6°F (3°C) below the tank
set point and finishes the call for heat when the tank
temperature reaches the tank set point.
2. The tank sensor included with the Lochinvar Squire
Indirect DHW tank (TST20015) is the only sensor
suitable for use with the SMART SYSTEM control.
Connect the sensor leads to the Tank Sensor terminals
on the Low Voltage Connection Board.
Failure to use the correct sensor may
result in the tank temperature being either
above or below the set point.
WARNING
3. If the TST20015 is not compatible with the indirect tank,
a tank thermostat can be used to control the boiler. The
tank thermostat should be installed per the manufacturers
instructions and wired to the DHW Thermostat terminals
on the Low Voltage Connection Board.
Variable speed system pump
If a variable speed pump is used in the primary loop, and a
0-10V signal is available from the pump speed control, this
signal can be used by the SMART SYSTEM control to anticipate
changes in the building heat load. By connecting this 0 - 10V
signal to the 0 - 10V SYS PUMP IN terminals, the boiler (or
cascade) can modulate up and down as the primary flow
increases and decreases.
Boiler pump speed output
This 0 - 10V output is available to control the speed of a variable
speed boiler pump. The SMART SYSTEM control will vary the
speed of this pump in order to maintain a minimum
T across
the heat exchanger, as well as prevent high limit lockouts when
the flow in the primary loop is extremely low. Connect this
output to the 0 - 10V input on the boiler pump speed control.
Rate output
This output provides a 0 - 10V signal that is proportional to the
firing rate of the boiler. This may be used by a BMS system to
monitor the actual rate of the boiler.
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.
