The pros and cons of floor versus wall air vents depend largely on whether the vents are connected to heating or air conditioning systems, according to The Baltmore Sun. Floor vents are best suited to warm air exhaust, while wall vents high on the wall are better for cooling.
Using natural patterns of air flow is key to choosing between floor and wall vents for a heating or cooling system. Since cool air sinks, using wall vents located high on the wall allows for the cool air from an air conditioner to circulate to floor level efficiently. Since hot air rises, it is more appropriate for floor vents. The same approach is best for vents that return air to the system, with floor collection vents for heating systems to return cool air and high wall collection vents for air conditioning systems to capture hot air.
It is also possible to use low wall vents for a heating system. This is less efficient than using floor vents, but in some cases the design of the building or heating system may require wall vents. One important caveat when using floor vents is that registers specific to floor vents must be used. Registers intended for wall vents cannot support the weight of a person and pose a safety hazard.