The Pyrosim fire simulation program was used to investigate changes in operating time as a function of the attachment height of a fixed-temperature detector. Operating times were analyzed for detector heights ranging from 4 m to 7.5 m, in 0.5 m increments, within a 30 m2 space. The fire source was modeled as a wooden pallet 1.22 m in height, and a Type 1 fixed-temperature detector with an activation temperature of 67.9℃ was used. The simulation results showed that operating time increased progressively with detector height, rising from 155.7 seconds at 4m to 206.3 seconds at 7.5 m a maximum delay of 50.6 seconds. Notably, larger increases were observed in the 4 m ~ 4.5 m and 6 m ~ 6.5 m ranges 14.9 and 11.5 seconds, respectively than those observed in other intervals. This suggests that critical height ranges should be considered when establishing detector installation standards. This study found that current design standards may not ensure adequate detection performance in high-ceilinged structures. In warehouses and industrial facilities with ceilings of 6m or higher, such delays in detector activation could hinder early detection, indicating a need for improvements