This study analyzed the effects of bidirectional heat trade of extra heat on the overall operational efficiency of interconnected thermal grids with empirical correlation formulation. A decision support operational simulation tool was developed to assess the technical-, and techno-economic performance of the complex and highly non-linear interconnected thermal grid system. From the techno-economic feasibility analysis for the test case of a hypothetical new thermal grid with a peak heat demand of 60 MWh, it was analyzed that the operating profit could be secured only for the gas engine, estimated to be about 8%. Moreover, the sensitivity analysis revealed that fuel price has the most dominant effect on operating profit in that the gas engine can attain 21% of operating profits as the fuel price is assumed to decrease by 20%. This study demonstrated the possibility of attaining favorable operational benefits with interconnected operation between thermal grids in terms of technological and techno-economic aspects with a newly proposed approach with empirical correlation formulation.