Thanks for all the info. I called my local heating rep & figured it out. Even though the circuits are 240v, it's permissible to only break one leg of the circuit for control purposes. I'll return the contactors and get one Berko LTR2-240 & one LTR1-240. This will allow me to control the 3 pieces of heat. The added bonus is that these operate silently, no 'bang' from the contactor closing.
