Happy 4th everyone. The guys at Tarm have been great answering all my questions, but I'm giving them the day off since it's a holiday Seriously though, I don't understand one thing in this diagram and it's bugging me. I'd really appreciate it if someone could help me out, so I don't bang my head against this all day. In the attached diagram, I don't understand how if you are heating from the wood boiler, or heating from storage, how you can get heat to the heating zones without p-1 running. I know I must be missing something simple. I would think that p-1 would only run when there is a call for heat and there is no fire in the wood boiler and storage is cold (just runs when fossil burner is running). Right now, my oil furnace circulator pump is on the return side of the manifold, so I essentially "pull" water back to the boiler. To set up my new system, it looks like I need to reloacate my existing "p-1" circulator pump so that it pulls heated water out of the boiler. I just can't get my head around how moving p-1 as indicated in the diagram won't create some kind of blockage for pumps c-1 and c-3. The water can't move through a non-running circulator pump can it? Like I said, a quick call to Tarm would straighten this out, but if anyone can help me today I'd be grateful.