That is a very complicated way of running simple circuits in my book. I would study up on a different way to get the returns back into 1 collector box. "T" fittings are not good and to have that many----well not good. T causes deadheading. "Y" fittings pointed in direction of flow would be much better. something is either back feeding pressure where it cant be or some other restriction down the line is causing pressure where its not s'posed to be.
