Not all heating vents are located on the floor; ceiling heating ducts are located in the ceiling and floor heating ducts are located in the floor. That seems obvious and inconsequential, but the location of the heating vents plays a major role in the heating of your home and the subsequent size of your utility bill.
Heating air vents are usually located in the floor, or in the walls along the baseboard, when the heating unit is located either in the basement or in a crawlspace under the house. The piping connecting the vents to the furnace, called the heat runs, generally run along floor joists and allow heated air to blow up into the rooms of the house.
Sometimes a furnace cannot be located under a house. This most often occurs when an HVAC unit is retrofitted into an older home, although in some parts of the county new homes are routinely designed with furnaces in alternate locations. The alternate location is usually the attic, simply because it is accessible. In this case, the heat runs are located along the ceiling joists and each heating vent is positioned in the ceiling. The vent is much more noticeable in this position, and a decorative heating vent cover is often used.
So, other than one being in the floor and one being in the ceiling, is there any difference? Yes, there is. Heated air is less dense than cold air, and so it rises. When warm air from a furnace is blown into a room through the floor, it warms the room as it rises to the ceiling. However, when heated air is blown into a room through the ceiling, it already occupies the area where physics is directing it to go. In order to provide warmth to you, in the lower areas of the room, it must be blown into the room more forcefully, pushed downward with a ceiling fan, or else additional warm air added until it fills the room.
Blowing air into the room more forcefully is not a good option. Air handlers are designed to move air at a certain cubic feet per minute. Passing the air through the furnace more quickly allows less time for the air to be heated, and is inefficient. It would also require more air to pass through in a given amount of time, meaning that your intake would have to be larger.
Running a ceiling fan while the heater is going seems counter-intuitive, but this often a good option. Most ceiling fans have reversible motors. The blades are pitched, and turning them in one direction draws air upwards while turning them in the opposite direction pushes air downwards. If they are slowly rotating while pushing air downward, the warm air gathered at the ceiling is circulated down in to the living area of the room.
The third scenario – simply running the furnace longer until warm air has completely filled the room, is the option most homes use.
Comments on this entry are closed.