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5 Field wiring
ModBus
When the optional ModBus interface module is installed, the
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 the terminals on the connection board and connect these terminals to the normally open contacts on the flow switch (FIG.
System supply sensor
1.By installing the system supply sensor into the supply of the primary loop, the temperature of the system 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). See the Outdoor Knight XL 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.
Boiler management system
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
2.Make sure the
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.
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Outdoor Knight XL Installation & Operation Manual
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 36 “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
If outdoor air reset is desired, the outdoor air sensor should be wired to the Low Voltage Connection Board at the terminals marked for the outdoor air sensor (FIG.
If a Thermostat or Zone Control 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
Communication between the Leader boiler and the Member boilers is accomplished by using shielded,