Note: When using Alternative Wiring diagram, the boiler oper-
ating control’s ZC terminal will see the load of the circulator(s).
Warning: When using Alternative Wiring diagram, wiring
instructions must be followed so power originates from the boiler
aquastat. Failure to follow these wiring instructions may result in
a secondary source of power being connected to the boiler that
may activate it under certain circumstances, causing injury or death.