I don't think we have a thread, solely for the cooling system, so I thought I would make one.
Below is a simple (perhaps too simple ) diagram I knocked up of what's going on.
Note
1/ The coolant temp. in C (f), to "bar" comparison I got via the Delphi ECU. Its temp. sensor is located on the thermostat housing.
2/ My crankcase doesn't contain that much water
3/ The RX3 doesn't have a pre thermostat bypass, hmm
so no real circulation in the engine prior to the thermostat opening.
Though it does have the usual "small hole" bypass in the thermostat .