Got a question for you,.. The other day I had to re-wire a 4 zone tankless boiler , one circulatro fed from the aquastat on the boiler the others from a taco control relay. I fed the taco control and then because this control was remote from the boiler , I ran the circulator (3 switched) wires over to a j-box on the boiler where I picked up the neutral for the circs. It is the same neautral just in a different spot the circs are only an amp each so there should be no problem there ... 300.3 may be ? you can see the control here page 90 tankless app.on the right.