Another plumbing schematic question

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.

Looks a lot more complicated then the way i have mine set up.

P-1 runs to supply heat to the radiators, whether it draws heat from the oil boiler, or from the wood boiler/storage side.

When C-1 is running water goes round and round through it, and P-1 draws off to the loads and returns to the loop. When C-1 is not running, P-1 pulls through the oil boiler because of the check valve between the supply and return manifolds, and because ZV-1 is closed.

Ew has it right. Whenever there is a call for heat from a thermostat p1 will run. By relocating the pump you will be pumping away from the boiler, supposed to be good. If you have more than one heating zone you might benefit from the use of an alpha pump for p1.

Once you understand the tarm diagrams you realize they are accomplishing quite a bit with a few tempering valves and relays.

Thanks for the responses. I figured that p-1 would have to be running for heated water to make it to the baseboard, but it isn't really mentioned in the documentation on pages 2 & 3 of the diagram. I think the diagrams are really good and I am starting to understand them. I guess you need to be able to read a lot more from the picture itself and not assume the write up covers everything.

Yes it's too bad about the documentation, they do a great job explaining some stuff, then they explain stuff that isn't even there, and then they gloss over the fact that the main pump has to run whenever there's any load. But sure don't want to look a gift horse in the mouth, Tarm has been awfully gracious in providing such otherwise high quality stuff for people to study and make use of.

One thing they talk about that isn't there is the Differential Pressure Bypass Valve, but as Mike suggests they have been pretty much been made obsolete by constant pressure pumps like the Grundfos Alpha and the Wilos Stratos.

Yea, the diagram has been a god send. Plus you can call them and they never seem inpatient or in a rush to answer your questions. This was just one of those things that I would have stewed on all day. I figured that pump had to be running, but because the rest of the write up was so detailed, and didn't mention it. You get the picture.

And I think I am going to switch out my current pump with one of those alphas.

Thanks again.