Installation for:

The black wire on the 24 VAC Relay Switch is connected to the common ground on the circulation pump, the brown wire is connected to the close on rise, and the blue wire is connected to the open on rise wires of the aqua stat on the DHW. The two yellow wires (low voltage) are connected to the output on the
MDC2001 zone valve controller.

Wiring diagram for
Circulator Control - Option A

Wiring diagram for
Circulator Control - Option C