Lochinvar 399 Low voltage connections, Thermostat, Outdoor temperature sensor, DHW tank sensor

8Field wiring

Low voltage connections

1.Route all low voltage wires through the knockouts in the rear of the boiler, as shown in FIG. 8-2.

2.Connect low voltage wiring to the low voltage connection board as shown in FIG. 8-3 on page 48 of this manual and the boiler wiring diagram.

Figure 8-2Routing Field Wiring

LOW VOLTAGE

CONNECTION BOARD

LINE VOLTAGE

JUNCTION BOX

LOW VOLTAGE

WIRING KNOCKOUTS

LINE VOLTAGE

WIRING KNOCKOUTS

Thermostat

1.Connect the room thermostat or end switch (isolated contact only) to terminals R and W, as shown in FIG. 8-3.

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.Connect the outdoor temperature sensor (FIG. 8-3) to the Outdoor Sensor terminals on the connection board to enable outdoor reset operation of the Knight XL. Do not install the outdoor sensor.

2.Mount the sensor on an exterior wall, shielded from direct sunlight or flow of heat or cooling from other sources.

3.Route sensor wires through a knockout at the rear of the boiler (see FIG. 8-2).

Installation & Operation Manual

DHW tank sensor

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.

The tank sensor included with the Lochinvar Squire® indirect DHW tanks (TST2032) is the only sensor suitable for use with the SMART SYSTEM control. Connect the sensor leads to the DHW Tank Sensor (AUX) terminals on the low voltage connection board (FIG. 8-3). Consult the tank manufacturer for application and performance when used with any other indirect tank.

￿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.

If TST2032 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 manufacturer’s instructions and wired to the DHW Thermostat terminals on the low voltage connection board (FIG. 8-3).

Auxiliary device proving switch

1.When the operation of an auxiliary device 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. 8-3).

High gas pressure switch

1.If a switch is provided to detect excessive gas pressure, remove the jumper wire from the terminals on the connection board, and then connect them to its normally closed contacts (FIG. 8-3).

Low gas pressure switch

1.If a switch is provided to detect low gas pressure, remove the jumper wire from the terminals on the connection board and connect them to its normally open contacts (FIG. 8-3).

2.If both a high and low gas pressure switch is used, connect their respective contacts in series, and connect them to the terminals on the connection board (FIG. 8-3).

DHW (Domestic Hot Water) thermostat

1.Connect the DHW tank thermostat to the Tank Thermostat terminals on the connection board (FIG. 8-3).

46

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 in line with the boiler.

2.Remove the jumper wire from the terminals on the connection board and connect these terminals to the normally open contacts on the flow switch (FIG. 8-3).