Guy King wrote:
The message
from The Natural Philosopher contains these words:

I can't see the point of a a thermo on the return path either.

It effectively sets the temperature of the slab. Regulating the inlet
will not control the temperature of the room as well.


It does not set the temperature of the slab.It sets the temperature of
the return water. Under conditions of slow flow and hot water the slab
takes on many different temperatures. The function of the thermo mixing
is to make sure none of these are excessive.