Let's assume we have a cold empty room (with no person in it, therefore - barely little air movement) and we want to heat it up.
In the room, we have a hot-air blower that has two fan speed-settings, but has the same number of active heating elements, no matter which speed setting has it set.
Therefore, when the fan is blowing slower (1st speed setting) the air output of is significantly hotter compared to the faster speed (2nd speed setting) where the air is slightly colder, due to the fact that the air doesn't have enough time to grab the heat from the heating-elements.
The question is: in which situation does the room heat faster? In the 1st speed setting (slow speed, hot air) or 2nd speed setting (faster speed, warm air) ? And why?