It's in Pascals buddy, it's not a chart for radiator PSI.
That makes more sense.
The point is, it's not a linear curve so 3° per psi is just a very basic estimate. My numbers are accurate.
I can see where it is not linear. I didn't state that 3°/lb. was exact under all conditions.
Not in a pressurized system it doesn't. Boiling water in a pot, yeah sure. Not inside a radiator.