Gasifer, One of the problems i have is in the living space there is 3/4 inch plywood under 3/4 inches of hardwood floor through the entire house. So i kind of have a cap on my warm cement. I bought a 2 way Air- and Slab thermostat but it would not work with my relay system for some reason. So i am hoping by controlling the slab temp tighter will help the warm temps. Cuz i know my slab cools off way before the air in the house does, causing it to work harder once a day rather then short cycles more often. And once the slab warms up it over shoots the set air temp. Huffdog i am heating 3000 sq ft of slab on grade.