Low airflow can make your ears hurt in one room compared to another. Use a barometer to measure the pressure in the kitchen, living room, bedroom, and other rooms in the house. If you notice different pressure measurements throughout the house, this is a sign there's not enough return air.
Symptoms include weak airflow and uneven cooling or heating throughout your home, with some rooms feeling much cooler or warmer than others. Homeowners should regularly check vents for consistent airflow. If you notice a significant drop in air pressure or uneven temperatures, it could indicate return air issues.
More Air Is Blowing In Rooms Near the AC Unit
A telltale symptom of an undersized return air duct is if the room closest to the air conditioner has more airflow than rooms farther away from it. That's because air pressure is high near the unit. But the farther you go, the lower it is.
Install More Return Vents
By installing more return vents throughout your home, they can trap the air and remove it, improving air circulation. A drawback with this method is that your ductwork needs enough space to support additional vents.
Instead, there should be at least one return vent in every room, with two or three being ideal. If your house has only one return vent, this is not a problem — make sure to keep the doors open in every room so the air can circulate properly. Make sure there are no furniture, draperies, rugs, etc. blocking return vents.
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.
Check Insulation, Windows and Doors
If one room is staying hot while the rest of your house cools down, it might be that a window or door in that room isn't airtight. Make sure all the windows are fully shut, then check the sills for a crack or opening that's letting air through.
As mentioned earlier, getting enough return air to your HVAC system is crucial for its proper functioning. When there isn't enough air, it strains the system but can also prevent latent heat from getting to the evaporator coil causing it to freeze, which can cause even further damage.
Ideally, there should be a temperature differential of around 14° to 20° Fahrenheit between the incoming air and the air being blown out by your air conditioner. This means that if the air entering the system is 75°F, the air coming out of the vent should be between 55°F and 61°F.
An anemometer, a test instrument that measures air velocity is used to determine the average airspeed in the duct. Then the average feet per minute is multiplied by the area of the duct in square feet to determine the airflow moving through the duct.
Common Issues with Return Ducts: Clogs and Leaks
You can generally identify a blocked air duct by a distinct drop in heating and cooling efficiency, increased energy costs, and occasionally a musty, dusty smell throughout the home.
The cost of adding a return vent varies from $200 to $500 per vent, depending on how close the vent is to the existing ductwork. You'll need to pay more if the vent is far from the ductwork, as you'll need to install more materials.
If you owe money to a federal or state agency, the federal government may use part or all of your federal tax refund to repay the debt. This is called a tax refund offset. If your tax refund is lower than you calculated, it may be due to a tax refund offset for an unpaid debt such as child support.
Common issues like leaks, disconnections, or obstructions within the ducts disrupt the flow of cooled air, causing rooms farther from the HVAC unit to suffer the most. In some cases, inadequate insulation of ducts can allow heat to infiltrate, further exacerbating the problem.
Proper airflow is crucial for an AC system to cool your home efficiently. Several factors can compromise airflow, including blocked or obstructed vents, closed or incorrectly adjusted dampers, and dirty or obstructed evaporator coils. These issues restrict the air's flow, reducing the system's cooling capacity.
Blocked Air Vents
Sometimes, the problem can be as simple as blocked air ducts. Furniture, curtains, or other objects can accidentally close or obstruct the vents, restricting airflow to a particular room. Check all the air vents in your home to verify that they are open and unobstructed.
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.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) provides guidelines for air changes per hour, and they vary depending on the room: bedrooms should have five–six, kitchens 7–8, and laundry rooms require 8–9 changes.