We have some problems with central heating in our multi-flat house and I would like to understand something. Some flats have old-style radiators, and almost every flat has different way to connect to central pipe.
Please, can you tell me which of these variants of radiator connection is correct one, for multi-story-flat house, so everyone would get heat and noone would be able to "disconnect" every other radiator on line.
There is drawing, editable in Google Drive.
First floor is bottom, fourth floor is top one in this diagram. Red rectangles are radiators, blue frames are individual flats.
In reality, best solution looks like the one in 3rd floor, but I'm not sure, if any water will get inside radiator, because of equal pressure points in input/output pipes for radiator.
Maybe there are other variants too? Could you give such and tell me why that is better.
EDIT: I have come up with best solution, from my point of view:
I'm not sure, if such 3-way valves exist, but that would be best solution, it doesn't block neighbours from getting heat and it balances incoming pressure, by giving away excess to neighbours. But I'm really not a plumber, I'm programmer :D