I can't cut out the outdoor furnace circulator, it's there to keep the furnace from over heating. I do like the separate aqua stat idea. And by in series I am going to put an aqua stat on the incoming outdoor line and wire that to the indoor boiler return line.Brimfield,
Did you not like my earlier idea? I can't understand your series idea without more detail.
Yea I plan to set the new aqua stat at 160*. There is a thermo valve on the furnace water line coming in that opens around 150*. This is to speed up the heating up of the water in the furnace and prevent condensation in the fire box. This will stop the indoor boiler from coming on.Yes,put an aqua stat on the supply from the outside boiler;that should do it. If your outside goes down for some reason your inside should pick up the load.I would set it 15-20 degrees below the outside boiler.