A heating designer is asked to create a three zone radiant floor heating system using a single speed 5-ton (60,000 Btu/hr) geothermal water-to-water 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 subfloor and well insulated.
The designer sets up a primary secondary system where each heat source connects to the primary loop using a pair of closely spaced tees, as shown in figure 1.
