We have been installing "air slab" systems since 1985. The design is our own and based on data from the Agricultural Technical Institute study of swine breeding facilities design. It uses ABS corrugated culvert and drainage pipe for the in slab ducting. Normally we integrate it with hydronic in the same slab. This allows the system to act as a back-up heat source. So far they work well and eliminate the need for AC.

The intake air usually is collected at a high point like a plenum in the chimney. The return air usually is ducted to floor level of the main living floor. On a slab on grade, they are one in the same.