Wiring A Cascade System - Westinghouse WBRU 80W Series Installation, Start-Up And Maintenance Instructions

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D. WIRING A CASCADE SYSTEM
When wiring the boilers for Cascade operation, select one boiler as the Master boiler. The remaining boilers will be designated
Followers. See "Setting Up a Cascade System" for more details.
Connect the system sensor and outdoor sensor/0-10V (if used) to the Master boiler. For the Cascade System to work properly the
system sensor must be installed. The location of the system sensor should be downstream of the boiler connections in the main system
loop. The system sensor should be wired to the low voltage terminal strip marked for the system sensor. The Master control will use the
water temperature at the system sensor to control operation of the Cascade System.
If outdoor reset/0-10V is used, the outdoor sensor/0-10V should be wired to the low voltage terminal strip marked for the outdoor
sensor/0-10V. If the outdoor sensor/0-10V is connected, the Master control will calculate the water temperature set point based on the
programmed reset curve parameters. If the outdoor sensor/0-10V is not connected the Master control will maintain the fixed water
temperature set point programmed into the control.
1. Connect the cascade communication cables to every unit. See Figure 35. Add resistor to the end of the last follower.
Every cable comes with one resistor. Use only one resistor on the cascaded system. Discard the rest.
2. Connect the system sensor to the Master low voltage terminal strip. See Figure 40. Thermostat, 0-10V, and Outdoor Sensor must be
connected to the Master only.
NOTE: The DHW sensor / aquastat must be connected to the prioritized Follower boiler.
Figure 35 – Example of Cascade Wiring
Figure 36 – Installed Resistor Figure 37 – Wired System Sensor
WHL-032 REV. 6.2.16