However, most HVAC contractors use a rule of thumb to determine the number of air vents needed. For example, for a standard residential HVAC unit, you'll generally need one supply vent and one return vent for every 100 to 150 square feet of living space.
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.
If there's not enough return air, your living room can be 10℉+ warmer or cooler than, for example, the bedrooms. Not enough return air in summer can cause rooms close to the central unit to be cooler and those farther from it to be warmer. In winter, rooms farther from the furnace can be too cool.
One of the most used methods is the HVAC duct sizing rule of thumb. In fact, even professional AC contractors might use this method to size the AC ducts in your home. According to this rule, you need to install an air conditioner of one-tonne capacity for every 500 square feet of the floor area of your residence.
Can You Have Too Much Return Air? Too much return air coming through your system isn't much of an issue because the fans and ductwork working to get that air back into the system only pull with so much force to make the HVAC system work correctly.
However, most HVAC contractors use a rule of thumb to determine the number of air vents needed. For example, for a standard residential HVAC unit, you'll generally need one supply vent and one return vent for every 100 to 150 square feet of living space.
Does Every Room Need Air Return Grilles? While it is a myth that air return grilles are required in each and every room in the house, it is definitely necessary to have more than one of these grilles installed at strategic places in the house. The most important place to have these would be the bedroom.
The air now has to re-pressurize to regain its turbulent flow so it can continue to push its way down the duct. It requires about 24′ or two feet to do this. This is the 'Two-Foot Rule?. Ideally, you should allow at least 24′ between takeoffs and at the end of any duct run.
Cold air return vents should typically be placed lower on the walls or the floor since cold air naturally sinks. This placement helps capture the cooler air faster and more efficiently, allowing it to be recirculated through the HVAC system for heating or cooling.
Up High: having an air return higher up on a wall will be better at sucking in hot air that rises. Making it more efficient at transferring this hot air back into your system to repeat the cooling cycle. Down Low: if you have your air return lower on your wall it will function better as a cold air return.
Blocked return vents are common causes of insufficient return air. It is crucial to keep return air vents unobstructed to ensure efficient operation of your HVAC system. Furniture placement, dust buildup, or closed vents can obstruct airflow.
When it comes to cooling your home, return vents are best installed near the ceiling so they can draw in any hot air that has risen. Supply vents should also be placed high on the wall for better distribution of cold air throughout the room.
One way to help combat this problem is to modify your cold air return ducts for better airflow. Whenever possible, expand your existing ducts vertically by cutting out pieces of wallboard and installing a new cover and air filter to fit.
1. Openings shall not be located less than 10 feet (3048 mm) measured in any direction from an open combustion chamber or draft hood of another appliance located in the same room or space. 2. Return air shall not be taken from a hazardous or insanitary location or a refrigeration room as defined in this code.
Typically, mortgage lenders want you to put 20 percent down on a home purchase because it lowers their lending risk. It's also a rule that most programs charge mortgage insurance if you put less than 20 percent down (though some loans avoid this). But it's not a rule that you must put 20 percent down.
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.
In fact, when installing return ducts it is always advisable to avoid putting them in bathrooms or kitchens. This would just simply cause the heating and air system to circulate cooking odors and moisture throughout the system.
While return vents don't always require filters, adding them provides additional filtration, improving indoor air quality and keeping dirt and debris out of your system.
Restrictive vents or grills: A vent that isn't the right size or shape can make a ton of unwanted noise. Some vents aren't made very well and have very narrow openings for air to enter or have vents that fall closed easily, which means that the HVAC system or furnace has to work super hard to get enough return air.
Simply put, it means you should never set your thermostat for a temperature more than 20 degrees cooler than the outside air. Why not? Most air conditioning systems can only handle a 20-degree difference between the outside and inside air temperatures.
Heating and cooling usage: Two air conditioners are ideal if you rarely use the second story of your home, such as for guest rooms or storage, or it requires a drastically different temperature setting compared to the main floor.
Inconsistent air temperatures throughout your home could be a sign of not enough return air. You may also notice poor indoor air quality that feels stuffy. You also may notice an increase in your utility bill since your HVAC system might be working harder due to the lack of return air.
The Secret to Comfort is Balanced Airflow
The current Supply Air vent pressurizes the room, until (in many instances) the pressure inside the room slows the airflow coming from the Supply Air vent! When we install the Return Air vent, the pressure is alleviated. The Return Air vent balances the Supply Air vent.
Generally, the size of your home determines how many vents you will need per room. If your room is larger than 100 square feet, you will need more than one vent (at least two) to really get adequate airflow to the room. If the room is smaller, you only need one.