CHF of downward-facing flat plate have been measured at various angle conditions in this study. Flat plates were heated in a saturated pool of water under atmospheric pressure. Among various factors, widths and lengths have been assessed for inclined flat rectangular surfaces, from horizontally downward to vertical positions. A high-speed camera was used to analyze the effects. Heaters showed no effect of length, but as width increased, the thermal limit value decreased accordingly. Between relatively narrow and wide widths, vapor motions were different, as shown in the pictures captured by the high-speed camera. As the width increased continuously, there was a width scale beyond which the results converged into each other. In addition, CHF values for the slightly tilted surfaces (75 deg in this study) showed higher results than that of vertical positions for 100 mm-length of stainless steel.