Either way will work ok as long as the system is designed that way from the beginning. The best place for the air conditioning registers (vents) will depend on who designs the system and the construction of your home. In some homes it is not practical to install the registers in the floor that have a concrete foundation. If you have a very low or flat roof it may not be practical to install them in the ceiling. Houses that are cooling most of the year have the registers in the ceiling and home that heat most of the year tend to have the registers in the floor.
should be on floor.
on the floor on the floor
Heating vents should be placed near or on the floor in a room because heat travels up not down.
Ceiling. Cold air fails
Heating vents should be located near the floor since hot air rises. If the heating vents are located near the ceiling the heat would stay there and not warm the room.
Heating vents should be placed on or near the floor because heat rises. In rising, it will warm the air of the room. If the heating vent were near the ceiling, the room would stay chilly, even though heat was being poured into it.
This is due tobuoyancy. Think about a hot air balloon as an example. Warm air has greater buoyancy than cooler air and will rise. Conversely, cold air will sink when introduced to a warmer atmosphere and this is why you see cooling vents placed in the ceiling.
up in the summer and down in the winter
because warm air rises.
Thanks for answering the question Should ceiling vents be directed towards the window or the room? NOT
yes
It would be better to place the heating vent near the floor because the heat will travel up and down, so that way the room would be heated evenly. If you place it near the ceiling, the heat would not heat the floor that well, since the heating vent sucks back in the heat