Tim,
it seems you want to use Prescribed Temperature (20 degree) for the initial temperature.
However, it is a constraint and will stay constant all through the analysis, so the surface can never reach any temperature other than 20 degree.
The strange result may be somehow caused by analysis finding a steady state very soon, because the temperature doesn't change.
I don't know a strategy to define different temperatures for the initial moment and otherwise keep it unconstraint.
You can only set one global temperature.
Maybe it is somehow possible to heat up block 1 within the analysis and then stop heating and look at what happens, when it reached 170 degree?
Thanks,
Gunter