Lochinvar 151 Runtime contacts, Alarm contacts, Wiring of the cascade, Field wiring

Installation & Operation Manual

8 Field wiring

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 water heater is responding to a call for heat.

Alarm contacts

The SMART SYSTEM control closes another set of contacts whenever the water heater 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 water heater is down.

Wiring of the cascade

When wiring the water heaters for Cascade operation, select one water heater as the Leader water heater. The remaining water heaters will be designated as Members. See page 58 “Configuration of the Cascade” for a detailed explanation of this procedure.

Connect the tank sensor to the Leader water heater. For the Cascade system to work properly the tank sensor must be installed. The tank sensor should be wired to the low voltage connection board at the terminals marked for the tank sensor (see FIG. 8-3). The Leader control will use the water temperature at the tank sensor to control the operation of the Cascade.

Communication between the Leader water heater and the Member water heaters 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. 8-3). If more than two water heaters are on the Cascade, daisy chain the wiring from the Cascade terminals on the second water heater to the Cascade terminals on the third water heater, then from the third to the forth, and so on. The connections between heaters can be made in any order, regardless of the addresses of the water heaters. Try to keep each cable as short as possible.

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