I tried to reproduce the mixin
 

I tried to reproduce the mixing elbow calculation presented in the Fluent tutorial.
It is about the mixing of 2 inlet water pipes at 2 different temperature (water at 25/40 degC Velocity = 0.2 & 1m/s; pipe diameter 40cm/10cm)

I performed a potentialFoam calculation. Then I successfully converged a calculation using simpleFoam (note: I couldn't have turbFoam converge on this case).

Now I want to do a heat transfer calculation and this is where I have a problem. It seems I cannot use simplebuoyantFoam solver because the thermophysical properties are only for perfect gases. Am I right? How can I use water properties. I've noticed that thermophysical properties for water are already in OpenFoam but I don't know if I have to recompile a new solver (how?) or not to use the water properties.

Thx for your help.