I have radiant heat in one of my houses, and with it not being occupied right now, but me; not wanting to drain the
water system, I wanted to see if I could keep the building above freezing without heat.
YES!
What happens is, the center of my
concrete slab is at 57 degrees, where as the outside of my slab, is far less and losing heat to the cold. But by just running my circulators, I am pumping water through the floor, thereby averaging out the water temperature throughout the floor. So far the lowest it has got down to in ambient temperature is -5 degrees (f), but it was blowing a gale, so it was -35 below zero (f) counting wind chill. Inside, with no heat on an unoccupied 2000 square foot home, it was 50 degrees inside.
I was pretty impressed.
It is too cold to be occupied, but there is
enough geothermal heat to have to pay for propane on a home not making income.