Here is my piping schematic. I finally figured out how to draw something where I could easily get it online. The circulator nearest the boiler will cycle water near the boiler until the danfoss opens at 140 degrees. At that point water will circulate through the twin 500 gallon storage tanks. If the house or DHW zones call, the primary loop circulator will start. The 3 way mixing valve diverts return water above the setpoint back to the zones. As a result, the reduced flow back to the boiler allows the boiler circulator to continue to charge the tanks with left over heat. If the boiler is off, the primary circulator will draw water off of the storage tanks. I just switched from a supply/return manifold scheme to the primary/secondary piping. Please let me know if I am missing anything glaring. Where do I need other items like checkvalves, isolation valves, drains etc. Thanks.