A subsurface warming system for an athletic field supplies positive pressurization to a particulate subsurface via a piping network with pipes that have openings. The system enables control of the temperature of the supplied air by varying the flow resistance at an output end of a constant air supply source, such as a positive displacement blower. By increasing the flow resistance at the output end of the blower, with a variably controllable valve equipped with a modulating actuator, the operating temperature of the blower increases and thereby causes a corresponding increase in the temperature of the air supplied therefrom. By varying the flow resistance, as needed, a user can vary the temperature of the air supplied to the piping network and eventually to the subsurface, to allow the problem associated with freezing of the subsurface during the winter season, for an athletic field that may be an artificial turf.