Abstract Radiant ceiling panels can be used in large-volume halls, e.g. vehicle repair shops and markets, to heat the entire or specific zones of the enclosed space. The system with radiant panels may be of small water capacity when just one or several units are installed over selected zones to provide additional heating. Depending on dimensions of radiant ceiling panel, its mounting mode and the temperature of its feeding medium, various thermal conditions are created under such panel. Thermal effects are also affected by the mode of thermal or cooling power control and dynamics of such control for an individual radiant panel or a set of panels. The dynamics of attainable radiant ceiling panel capacity was investigated and used as the grounds to determine general requirements for time-domain automatic control programs and those for operation of the controllers. The results presented from the examinations carried out for water radiators are not intended to delineate the requirements for all automatic control loops for water radiators; they are aimed at attracting attention to issues to be considered when preparing the algorithm of automatic control in particular situations.