In this study, a numerical investigation has been performed to examine the effect of the height of panel radiators above the floor. A radiator of the Panel-Convector-Convector-Panel (PCCP-type 22) was located in front of the wall where a window was placed in the 3D computational domain. Analyses were made using distances of 0.0, 1.0, 2.5, 5.0, 7.5 and 10.0 cm between radiator and floor. The results suggest that the thermal efficiency of the radiator is lowest at a level of 0 cm, which is the case when the radiator is placed on the floor. When the radiator level is insufficient, the air intake is not enough to obtain maximum heat transfer between the panels. If the radiator level is more than the optimum level, although the temperature decreases in the occupied zone, it is accumulated in the ceiling part of the room. This study also suggests that the air velocity in the collectors between the panels is a dominant parameter that affects the efficiency of the radiator.