Panel radiators are widely used room-heating devices. Due to the temperature difference between the surrounding air and the panel surfaces of the radiator, natural convection driven flows occur around and above the radiator. In order to maintain comfort conditions in the indoor environment, it is important to understand the flow of the heated air above the radiator. In the present study, particle image velocimetry (PIV) measurements and numerical simulations using Computational Fluid Dynamics (CFD) have been carried out for radiators with different convector dimensions, in order to examine the airflow above radiators. The airflow above the radiators has a direct effect on the internal environmental quality; hence, it is important to understand the effect of different dimensions of convectors on the airflow above radiators. The non-uniform temperature distributions on radiator panels, showed different velocity profiles along the radiator, and higher velocities have been obtained near the water inlet. In addition, higher velocities have been obtained in the vicinity of the wall where the radiator was mounted. In general, the flow is guided towards the wall, and with the increase in convector height, this deflection in flow occurs at an earlier stage above the radiator. The investigations showed that with the change in the convector dimensions, similar flow conditions above the radiator occur, hence similar comfort conditions could be obtained. At the same time, it will be possible to use less material in the manufacturing process, one of the goals of this study, which reduces manufacturing costs.