Enhancing the heat output of panel radiators, which are one of the most widely used heating systems, could play an important role in energy saving. The aim of this study is to investigate the heat output of panel-convector-convector-panel (PCCP type 22) radiators for different connection positions, and inlet/outlet temperatures using laboratory measurements and CFD analysis. Experimental studies were carried out in a climatized room. Same conditions were implemented in a CFD code. CFD results were validated with the experimental measurements, and a good agreement was obtained. The highest heat output for all inlet/outlet temperature ranges was obtained for the top-bottom-opposite-end connection position. In addition, the most uniform temperature distribution on the front panel was observed for the same connection position. It was observed that the effect of radiation on the heat output of the radiator could not be neglected. The simulation results performed for constant panel temperature showed a high increase in'heat output. So, it is important to uniformly distribute the water inside the water channels to increase the heat output of the radiator. It was obtained experimentally as well as numerically, that the top cover of the radiator has a degrading effect on heat output of the radiator. The findings of this study are important in the design of a new radiator with higher heat output as well as the optimum use of radiators. (C) 2017 Elsevier Masson SAS. All rights reserved.