This study investigates time-dependent free convection heat transfer and buoyancy-assisted flow over a horizontal heated plate within a vertical channel for two distinct scenarios: one stand alone and second involving tilted plates and varying plate positions. The temperature difference between the plate and air induces buoyant airflow. The study explores the impact of plate tilt angles and positions on time-dependent heat transfer coefficients due to varying buoyant airflow. The primary focus of the research for both classes of study is on the effects of the tilt angles (which control the change in flow blockage ratio) and positions of the heated plate on the time-dependent heat transfer coefficients due to the time-dependent buoyant airflow. As the blockage ratio increases and the positions of the heated plate in the vertical channel decreases, the influence of time-dependent buoyancy on the time-dependent Nusselt number weakens. The time-dependent Richardson's number varied from 7.4 to 9.6 throughout the tests. Based on the experimental data gathered from corresponding flux geometries and test conditions, the CFD model was validated. We have also developed a set of empirical correlations for predicting time-dependent Nusselt numbers for a time-dependent Rayleigh number range of 2000 < Ra < 7500, the dimensionless height of the heated plate from 0.507 ≤  ϕ  ≤ 0.551, and a flow blockage ratio of 0.08 ≤  χ  ≤ 0.024. At orientations where γ  = π/2 and γ  = π/4 , it has been observed that the heat transfer at position ∅ 1 is higher, whereas at γ  = 0 orientation, ∅ 1 heat transfer value is lower compared to the others. When the time required for the heated plate at all positions ( ∅ ) to reach thermal equilibrium with the ambient environment is compared with respect to orientation angles, it has been observed that the γ  = π/2 orientation angle reaches thermal equilibrium in the shortest time compared to the γ  = π/0 and γ  = π/4 orientation angles.