Lochinvar 51 Thermostat, Outdoor temperature sensor, DHW thermostat, DHW tank sensor, Flow switch

Installation & Operation Manual

8Field wiring (continued)

Thermostat

1.Connect the room thermostat or end switch (isolated contact only) to room thermostat 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. If fixed temperature operation is required, do not install 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.

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. Consult the tank manufacturer for application and performance when used with any other indirect tank.

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.

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.Connect these terminals to the normally open contacts on the flow switch (FIG. 8-4).

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 ΔT 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

￿WARNING

Failure to use the correct sensor may result in the tank temperature being either above or below the set point. Failure to consult the manufacturer of the indirect tank, when the Squire is not used, may result in decreased performance or the risk of scald injury.

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.

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