Heating system design utilizing potable water

[Shelterman]

The big problem would be to have a circ for the LP boiler that would push just hard enough that the all flow would come from the LP boiler and none additional sucked by the load circs through the check valve, but not push so hard as to force flow through load circs that aren't calling for heat.

Yeah, I see what you mean. By putting the LP spoiler on the other side of storage, we've created this problem.

A while back you turned me on to www.pmengineer.com which taught me about the concept of "hydraulic separation". Correct me if I am wrong, but I think that's the issue here. The storage tank hydraulically separated the LP boiler from the loads before the last change. Would another hydraulic separator correct this problem? I have no idea what the cost is on one of these, but if the cost is prohibitive, it looks like a simple one could be constructed pretty easily for this purpose.

David