Having several return vents (ideally one in every room, but even two or three is better than just one) creates consistent air pressure. If you have one return vent, your home is fine. Keep the doors to each room open so air can properly circulate.
The earliest HVAC systems featured a large, single return vent placed somewhere in the middle of the home, but this is not the most effective system. Instead, there should be at least one return vent in every room, with two or three being ideal.
In an ideal situation, every room in your house should have a return vent or grille along with the supply vents that are typically in each room. Some homes are built with just one or two main return vents in order to cut building costs, but if you're going for maximum efficiency and comfort, this isn't an ideal setup.
Most homes across the U.S. have forced air systems and in newer homes there will be cold air return vents placed at both the ceiling and the floor of many rooms. Having two air return vents allows you to seasonally control which air is returning to the HVAC system.
Your Home May Not Have Sufficient Return Vents
Having a number of return vents (preferably one in every room, but also 2 or three is far better than just one) creates regular air pressure. If you have one return vent, your house is great. Maintain the doors to every room open so air can properly flow.
This balances the airflow through the system and ensures that there is plenty of air coming back to be reconditioned, filtered, and sent back out again through the supply ducts. If there is not enough return air available, your HVAC system will not heat or cool properly.
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.
Return air ducts explained
As with any pump, you need to get supply back to it—in this case, air. The return air makes it easier for your system to push cool air (or warm during winter) into a room by allowing the air in the room an escape back into the system.
Return air openings for heating, ventilation and air-conditioning systems shall comply with all of the following: 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.
You can add a vent to existing ductwork if your AC can handle it. This can provide comfort in rooms not served by your HVAC system. It can even improve indoor air quality and increase your home's resale value.
If your house has only central air return grille then you will notice that the return air will struggle in order to find a way back to the furnace. As a result, the pressure in each room will vary and you'll experience uneven room temperature.
A house's heating, ventilation and air-conditioning (HVAC) system uses return air vents to facilitate air flow to and from the system's air ducts. Most rooms in the house that have an HVAC vent also should have a return vent, with the exception of the bathroom and kitchen.
A return air drop replacement will run around $300-$400, including installation. In rare cases where a second drop needs to be added, the cost can be up to twice that amount. Sometimes, one or two individual duct runs need to be modified or added, for situations like the room addition we mentioned earlier.
If you prioritize heating, put the HVAC and vents in (or below) the floor. This principle works for return vents as well. Place returns for cooling in the ceiling where the warm air congregates and heating returns in or near the floor where the cold air congregates.
Long story short: It's never a good idea to cover up cold air returns.
For your furnace to run efficiently and your home to heat evenly, this airflow must be in balance. In other words, the amount of air that your furnace “breathes in” must equal the amount of air it “breathes out.” Cold air returns are what allow your furnace to “inhale” your home's air.
You Don't Feel Enough Return Air
Lick your finger and place it near a vent that's producing airflow. While this won't measure airflow as a quantity, it can help determine air velocity. If the return air doesn't feel sufficient, have the system evaluated by a professional.
Return air vents are generally located near the center of the homes. Older and newer homes often have one register per floor, but homes built from 1960-1990 may have a cold return air vent in each room.
An air return on the floor collects much more dirt and debris such as hair and lint. For this reason wall air returns will require less frequent cleaning. Floor air returns must be clear of obstructions and heavy furniture. Transferring your air return to the wall will allow you to utilize your floor space more freely.
Each bedroom needs either: A return air grille ducted back to the furnace; A through-the-wall transfer grille connecting the bedroom and the adjacent hallway; or. A crossover duct (a jumper duct) connecting a ceiling grille in the bedroom with a ceiling grille in the hallway.
Hot air rises and cool air sinks. Therefore, opening the right return vents in the summer and winter significantly improves the distribution of air by your forced-air system. You'll also enjoy more even heating and cooling throughout your home. In the summer, open your high returns and close the low ones.
I see no problem in doing that, as long as the return duct is sized big enough for the both rooms. I would think it would need to be at least the size of both room supply ducts combined. An alternative would be to use a Jumper duct. Consider placing them at slightly different heights to limit light leakage.
Higher utility bills. Less comfort. That big central air return could be causing all sorts of problems! Though rare, negative pressure in an upstairs hallway can be so severe that the central return starts pulling CO from gas appliances.
Cold air returns are located on interior walls in a home, typically close to the floor or low on the wall. You want to make sure that cold air return vents are not blocked or covered by furniture so that your home can get proper air circulation.
Since an oversized AC is too powerful for your home, it will quickly cool your home then shut off, which can raise your energy bills and wear out your AC (from all the starts and stops).