This is a basic question it's just im not sure what the answer is because i have not had much experience with this. I have a customer that has 4 zones and needs a controler replaced. Each zone only has one wire comming in to the controler and then one single Ground for the controler. Is that normal? When I have replaced control valves they always had two wires. Are there both one and two wire options available for control valves and controlers? How is this type wired up. What do I need to know on this? Thanks.