Let's look at the case where you desire to desolder a component from the P.W.B. In this case, just place the HAKKO HR-820 directly under the corresponding component and push the START/STOP button. In other words, applying hot air to the desired section is local heating.
By preheating the desired section by local heating, you can avoid the problems (such as damage of heat-sensitive components or P.W.B. warping due to overheating) caused by having to set the temperature higher.
* Please keep a gap between the hot air outlet and the PWB for more than 5mm to allow the air to flow. When there is not enough space for the air to flow, the fuse may blow up.