Was just talking to the dealer I am getting my EKO 40 through. He is recomending going to all pumps for the four zones versus running one pump and zone valves. His comments were, zone valves are harder to replace and identify which one if having a problem, or where the problem arises, zone valves build up with water contaminants faster so need replacing more often. Pumps he says go out just unbolt and replace zone valves are difficult to replace. ????????? So what is the scoop one better then the other?