Ceiling vents do a better job cooling and floor vents do a better job heating. If your priority is cooling, put your HVAC in the attic and ducting and heating vents in the ceiling. If you prioritize heating, put the HVAC and vents in (or below) the floor. This principle works for return heating vents as well.
Since heat rises, the heating vent should be as low as possible (floor). Since heat always stays near the ceiling, when you install A/C vents, they should always be installed as high as possible (ceiling).
Air Ducts Near the Ceiling Are Most Effective
This makes the air circulation less effective and may cause the entire HVAC system to work harder than it needs to. Additionally, vents placed near the floor are at a greater risk of being clogged with dust or other debris.
Generally in colder climates floor registers are the most efficient since hot air rises. Ceiling registers are better in hot environments since cold air sinks. Wall registers are tricky because they don't do either all that well and are better as returns.
The Automatic Air Vent should be installed at a high point in the sealed central heating system, as air naturally accumulates at elevated points. Typical installation points include near the boiler, radiators, or air separators.
If it's cold outside and your vents are located near the ceiling, then you need to point the vents downward. Your goal is to increase the circulation of air inside each room as much as possible.
THE BASICS OF HEATING AND COOLING
So with that in mind, we typically locate vents on the floor to allow the warm air to heat the entire space as it moves upward. In the case of your return vents that pull air to go into your HVAC system, we also locate these on the floor.
No insulation means your unit lives in extreme conditions for a better part of the year. You'll lose warm air in the winter and cold air in the summer. This can cause breakdowns in your system or a need for more frequent maintenance. It is also a very inefficient way to run your HVAC system.
Vent Location
This means placing them in areas where the air can circulate freely without obstructions. For example, placing a vent behind a piece of furniture or in a corner may impede airflow and cause hot or cold spots in the room.
Placing the heat vents beneath the windows is actually best for efficiency and proper airflow. Essentially, you want to target your warm air where the home is cold. If you'd placed heat vents in your ceiling, for example, then this part of the home would get hot, neglecting to heat up the sides of the home as much.
Install a vent near the ceiling where it won't be obstructed, which can reduce efficiency. In hot climates, floor vents are effective for providing cool air. In a humid location, install floor return vents and use ceiling fans to conserve energy. Vents near the ceiling help cool air circulate and can increase comfort.
While living in the south, you may have noticed that extreme heat is more common than extreme cold. If you remember basic science, you'll know that hot air rises, and cold air sinks, making ceiling vents the delivery location of choice for places that often experience warmth and humidity.
What room should return air ducts not be installed? Return air ducts should generally not be installed in rooms with high humidity or areas prone to moisture accumulation, such as bathrooms or kitchens.
Return air vents are usually found in the lower wall of a room or hallway. Ideally, your return air vents and supply vents should be on opposite sides of the space. Otherwise, you may be pulling some of the heated or cooled air back into the system before it has a chance to circulate.
That magic number is 100 square feet. If your room is larger than that size, then you'll need at least two vents (the number will increase the larger your room). However, if the room is smaller than that, then it means you will only need one vent there.
Return ducts extract air from the living spaces back to the HVAC unit, feeding either your furnace or air handler. Return vents are usually larger than supply vents and are called grills. A filter is often installed either deep inside a return duct or right at the return grill to protect your HVAC unit from impurities.
A general guideline is homeowners need one square foot of roof vent for every 300 square feet of ceiling space, if your home has a roof with a vapor barrier, or 1:300. If not, you should have one square foot of roof vent for every 150 square feet, or 1:150.
One per room is ideal, but placing two or three in central locations can provide enough air circulation to maximize the energy efficiency of your HVAC and optimize indoor air quality, so your family stays healthy. If your home has multiple stories, you should have at least one return air vent per floor.
It's important to remember that static vents serve a purpose, especially in older homes. They provide ventilation to indoor spaces, help regulate indoor temperatures and prevent the build-up of excess moisture in wall cavities and rooms which can lead to mould outbreaks and damage to building materials.
In short, wall mounted return vents are more effective for air conditioning, and floor mounted return vents are more effective for heating.
If your ducts aren't insulated, you're probably paying way more than you should to cool and heat your home. And since your HVAC system will need to work harder to power through the thermal loss (or gain) that's going on in your ducts, you'll have to replace it sooner than if you had insulated ducts.
On the positive side, placing vents under windows can help with airflow and prevent cold spots in the room. This is especially useful during winter months when heat tends to escape through windows, leaving areas near them feeling chilly.
For heating, floor registers should go near windows or interior walls. For cooling, ceiling registers should go over the center of the room or above windows to optimize air circulation.
For air circulation. Hot air rises (because it is less dense than cold air, having fewer molecules per square inch), so for the most part warmer air goes through the vents above interior doors while colder air moves from room to room through the gap at the bottom of an interior door.