Seems like some folks have their thermostats in the floor from reading the above - I thought they had to be in the room on the wall?
FWIW. More and more I've come across ufh systems that havent been wired correctly and as result people think they aint working correctly. The wiring is cruical.
Mine was wired incorrectly and it constantly ran heating and cooling the water evey alternative minute - A disaster.
A friends was wired incorrectly and his wood pellet boiler generated the heat, sent it round in a loop, skipped the rooms, and never fired down.
With a gas boiler the boiler will keep the room tepid by using a trickle of gas when its warm as opposed to a gigantic blast used to fire up when the house is cold. With my correctly wired boiler keeping it on 24/7 cost no more than running it on radiator style timings.
I even moniter the effect of switching the heatin off for a long weekend and then reheating the house on the evening that I returned. I compared this with leaving it on for a full weekend. The cost was the same. My boiler is a gas glowwarm.
I'd say observe your systems and count the meter units and take other opinions.
UFH systems generate a max of 45 degrees of heat to the floor and that will be cooled down before the water completes its heat. Once switched off surely there is no way the floor can continue to heat your house all day?.