A direct contact segmented column heater is described. The heater is capable of a broad heating and cooling range, and exhibits a very rapid response, with heating and cooling rates better than 350° C. min−1. In one configuration one or more of the individual heating devices are provided with full independent control and temperature feedback, and developed to provide excellent thermal stability at all temperatures. The heating devices or in other words active thermal transfer devices are capable of bi-directional operation, selectively heating (i.e., providing heat to) or cooling (i.e., withdrawing heat from) a column and/or contents of a column.