Well, everything is in (except 1-wire montioring), tank is insulated, etc. I can now confirm that my system thermosiphons when the boiler is NOT producing heat. I thought that 80' of in ceiling basement pipe, 5' drop to get underground, 80' undeground, 4' rise to the shed, and 5' to the top of the boiler, plus all the fittings, would be enough resistance to keep the reverse flow from not happening. Good news is that I don't have that much pressure drop!
To solve this, I am contemplating putting a swing check valve in the return line near the storage tank. Comments, suggestions, concurrence?
[Corrected diagram]
To solve this, I am contemplating putting a swing check valve in the return line near the storage tank. Comments, suggestions, concurrence?
[Corrected diagram]