Armstrong reccomends that you do a moisture test on the slab to test for the amount of moisture present.
What you do is take some 6 mil plastic ,cut into 1'x1' sheets,you will need 3 for the first 1000 square feet then another 1 for every 500 square feet.Tape them to the floor using duct tape and seal the edges real good,let sit for 24 hours.After that you need to check for any darkness in the concrete or drops of water if they are present then you would need a calcium chloride test to see how much moisture is there.Armstrong says 5.0lb/1000 square feet /24hours.
I don't know if i would just seal the concrete without testing first,sorry Dell,without testing the concrete first cause if there is significant moisture there then the sealer would not do any good anyway.
Is this slab on grade?Below?
I'm with Dell on the nu-heat thing much better sysem than the easy heat,you try that yet Dell?Real pain in the a##