This is the most common in renovation because is easy to install.
Slab is knuckled, 5 treaded, really strong for heavy installers.
Properly installed according to the drawing through knuckles (5 treaded)
The tube diameter is 17×2 choice PE Xa or PE-RT (both with evoH oxygen barrier).
Distribution you have to choice between simple manifold and group with reduction temperature (fixed point or with external probe control).
Concrete screed at least 40 mm. (above the knuckle of the slab), must be addict with superplasticizer
LA 45