I haven't seen a proper drawing of the complete system which includes heater and cooling circuits. The workshop and parts manuals show schematics for the two systems although they're not on a single diagram. The cooling hoses are fairly obvious and you can tell the right way to connect them from the Parts Manual diagram.
I can't help on the Renault engines but on the TC the heater has two connections to the steel pipes in the backbone, on mine the one on the passenger side is from the heater valve on the cylinder head/thermostat housing and the other steel pipe connects to the outlet from the water pump. I've added some text to a pic of the steel transfer pipe in question because trying to describe in words is beyond me !
Brian