  We propose a novel molecular device that pumps heat against a thermal
gradient. The system consists of a molecular element connecting two thermal
reservoirs that are characterized by different spectral properties. The pumping
action is achieved by applying an external force that periodically modulates
molecular levels. This modulation affects periodic oscillations of the internal
temperature of the molecule and the strength of its coupling to each reservoir
resulting in a net heat flow in the desired direction. The heat flow is
examined in the slow and fast modulation limits and for different modulation
waveforms, thus making it possible to optimize the device performance.
