I was kind of thinking that somehow the dial may have been "repositioned" in such a way, where the "60°" mark would actually be equal to "70°" ambient temperature, but after seeing the quoted text below, I would say 99.5% chance this is the "Problem"!
His daughter told me she thinks he just likes to tinker with things too much and keeps turning the dial up and down and won’t leave it alone
Line Stats aren't the most accurate things, but they do have at least +/- 5% tolerances with something like a 3° Differential.
As was mentioned before, radiant heat will heat up objects directly, not the enviromental air directly.
This seems to confuse some people with radiant heat strips (ceiling mounted, encased in the Plaster of the "Lid"), as they do not feel warm air immediately.
As a result, they start spinning the Line Stats' dial up and down - eventually calling for a service tech to check things out.
One of the disadvantages to recessed radiant heat strips is when one has to be replaced. The ceiling (Lid) will require patching and texture.
Typical failures come from Toggle Bolts and Lag Screws going through the cable - commonly occurs when someone wants to hang something from the ceiling, encounter "a tough spot" in the plaster, then find out later there is no heat in that room!