When you install a system and make sure the correct nozzles are in all the heads, how do you compute the precipitation rate for a zone? Using the flow/performance/precipitation charts for the nozzles one may be using, do you take the nozzles within each zone find there precipitation rates, add up all the rates then divide it by the # of heads within that zone? The reason for my question is to make sure/confirm the method, since I am installing many Irritrol smart dials and it ask for the zones precipitation rate. I work my arss properly installing the systems and take the time to program these controllers, I hate to have to reprogram them all. All help is appreciated good or bad.