Sloping Evaporator Thermoprobes are found on the majority of existing passive subgrade cooling system installations beneath slab-on-grade structures. These units utilize a sloped evaporator to insure that the condensate will flow from the condenser to the lowest portion of the evaporator. Typically, evaporator slopes are between 10% and 3% - with the median being 5%.
Structures founded on grade over permafrost utilizing Thermoprobes for subgrade cooling also have two other very important components of design: subgrade insulation and NFS fill. the typical thermal design methodology for this type foundation economically balances the three major components. The insulation reduces the heat load on the subgrade and limits the thawing of the underlying NFS fill during the summer season when the Thermoprobes are dormant. The NFS fill contains the seasonal thaw and provides a heat sink beneath the structure. The Thermoprobes remove heat from beneath the structure primarily during the freezing season and refreeze the NFS fill so that it is completely frozen at the beginning of the thawing season.