So I thought I was good to go. Just finish 600 feet of radiant (loop feed by new green taco zone valve in photo) and went to fire it up, but when I opened the zone valve no flow through that loop (just a momentary flow for a minute), that's when I realized you can not put a pump before the mixing valve (my mixing valves think there is a failure on the cold supply and they close of the hot).. I am using a primary secondary set up with grundfos alpha on the secondary supply feeding six zones (two only used now). So as you can see in the photo I put the alpha pump first and that feed the header. The header has zones valves (only two installed as of now). After the zone valves I have mixing valves (one taco 5002 and one danfoss esbe valve), which allow me to adjust the temperature as desired. This is all been fed from a tarm innova 30 with 750 gallons of pressurized storage. I decided to mix at each zone because my zones all require varying temperature (i.e. indirect dhw, panel radiators, and under floor radiant). I decided to use the alpha pump because I liked the efficiency. Well looking back I probably would of just went with circulators for each zone inlieu of zone valves but that ship has sailed. I am committed with what I have and need to make it work. Is it acceptable to move the alpha pump to the return side of the secondary loop? Instead of pushing water through the zones I would pull it? Would this solve my mixing valve shut down problem. Or is there a easier solution? Side note, My expansion tank is hooked up at boiler about 8 feet away from this mess.