Hi Chris,
Your plan sounds similar to my system. Check out the link in my sig.
My boiler only feeds storage-supply to top, return from bottom with a very defined thermocline while charging storage.
Infloor heat supply draws off the top of storage and returns to the bottom through a dip tube. Again, no mixing while discharging storage.
Maintaining stratification while discharging storage will be more important for me when I add DHW to the equation.
Constant circulation with outdoor reset is simply awesome! I find I am very happy with a 20
![DeltaT ::DT ::DT](/talk/styles/default/xenforo/smileys/deltat.png)
T on my low temp radiant floors, allowing half the gpm's vs a 10
![Fahr ::F ::F](/talk/styles/default/xenforo/smileys/f.png)
![DeltaT ::DT ::DT](/talk/styles/default/xenforo/smileys/deltat.png)
T. Maybe this would work for you or maybe not but a variable speed ECM pump would allow you to pretty much dial in whatever temperature drop you want. I have my Alpha set on fixed speed 1, drawing 6 watts and pumping 1 to 2 gpm depending on what kind of flow the TRV's are allowing. Of course my heat load is less than half of yours but less electricity is always better and constant circulation doesn't necessarily mean more electrical consumption vs on/off control.
Can't really offer anything on the mixing valve recommendation besides outdoor reset.
Not sure this helps much....BTW nice work on the house! Love the aesthetic value (just not the thermal bridging).
Noah