Question about Nofossil's simplest pressurized storage design

I really like this simple design but have a question: When the load circulator calls for heat and the boilers are cold, the water goes in the bottom and out the top of storage. How does the water keep from circulating through the boilers as well?

I'm sure this is simple and I'm just missing something. thanks.

My circulators, Taco 007, have an integrated flow check (IFC) built into them. Oops, I forgot to add that I have several circulators. When the zone circs are calling and the boiler is cold the boiler/primary loop circ is off at that time. So it draws from the tank and returns to the tank.

Do most circulators have IFC's? I have Grundfos 3 speeds and the check valves are in.

I do not know the answer to your question about if your Grundfos 3 has an IFC.

How many circulators do you have in the system? If your boiler is cold then the circulator for it will be off, I think that will prevent flow going through your boiler. Hopefully someone else will chime in and make sure I am correct about that.

If you're saying that you're Grondfos pumps have check valve installed them I would say there are flow check pump. Without a part number or picture I can't say 100%.

Here you go: http://www.outdoorfurnacesupply.com...nges/grundfos-ups15-58fc-circulator-pump.html

It says "flow check"?

Unless you removed the white plastic check valve from the discharge side it has a check valve.

gg

Two things:

1. The flow check in the boiler circ provides a bit of reluctance - need enough pressure to crack the check valve
2. The near tank plumbing should be arranged so that the preferred flow direction is through the tank. Hydrostatically speaking, the boiler loop should be a close approximation of closely spaced tees such that there is virtually no flow-induced pressure drop between the tees that connect the wood boiler to storage

The wood boiler return mixing valve will not flow to load if mixing valve is cool. If using storage for power fail cooling then need mixing valve bypass and siphon circuit. Load circulator won't draw cool water from boiler if it has hot water right there at the top of the storage tank on account of hot water rises.