A heating designer is asked to create a three zone radiant floor heating system using a 5-ton (60,000 Btu/h) geothermal heat pump as the primary heat source, and a mod/con boiler as the auxiliary heat source. Because of the symmetry of the building, each zone will have a six circuit manifold station with nearly identical circuit lengths. All the floor heating circuits are underfloor tubing with aluminum plates stapled tightly to the underside of the sulfuring and well insulated.