A lack of return air can cause your HVAC system to overheat, leading to frequent shutdowns or overheating warnings. This overworking can also result in the air conditioner blowing warm air, especially in high temperatures.
Yes, as the back pressure from the circulating fan would not allow conditioned air to enter the room. The return air duct must be larger than the inflow duct to ensure circulation back to the return air plenum to the air conditioner.
Inadequate return air to a furnace will cause the heat exchanger to get hotter. Depending on the amount of air being restricted, this can cause the heat exchanger to crack and leak combustion gasses into the air flow. This happens far too commonly in residential units.
Depending on the season, your HVAC system recirculates warmed or chilled air throughout your home. Two types of vents are required: supply vents and return vents.
Reduced efficiency: Your HVAC system will work less efficiently if you block a return air vent. This will make the units use more energy and will raise your utility costs.
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.
You should never close your HVAC return vents, but supply vents can be adjusted to improve home comfort. In this blog, the trained professionals at Damiani's Comfort Design explain the strategy behind opening your supply vents and the dangers of keeping your return vents closed.
You might notice hot and cold spots or uneven temperatures from room to room. Early identification of these issues is key; check if some areas feel stuffy or stagnant. Consistent discomfort in specific rooms is a clear sign of poor air circulation.
The cost to add a return air vent is between $200 and $750 per vent, with the average cost being about $350. Adding a return air vent can be a valuable upgrade to your home's HVAC system, improving air circulation and overall comfort.
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.
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.
Cavities (or interstitial spaces) within walls are also sometimes used as supply- or return-air pathways.
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.
Return air openings for heating, ventilation and air-conditioning systems shall comply with all of the following: 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.
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.
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.
If your HVAC system is designed this way, blocking off a single return vent can wreak havoc on the system and lead to: Pressure imbalances that let allergens and pollutants get pulled into your air supply from unconditioned areas.
Duct replacement costs typically range from around $20–$60 per linear foot, based on our team's market research. For example, if your home has 100 feet of ductwork, a complete replacement can cost between $2,000 and $6,000.
Having an air return vent in every room can increase the energy efficiency of a home by recirculating the air internally rather than drawing hot or cold air from outside. However, this can pose a slight staging problem since furniture and draperies should be kept clear of cold air return vents.
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.
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.
Add Return Ducts
There will be times when even a properly-sized return drop and trunk won't deliver needed air. In those cases, we look for alternative ways to get additional return to the system. Some house layouts are easy to add a floor return in an open area , others require more creativity.
Many central air conditioning systems don't get enough return air. When they don't, you can have all sorts of problems. Hot spots and cold spots throughout your home, indoor air quality problems, premature component failure… It's a long list of really bad stuff.
Closing the vents doesn't do it any favors. In fact, instead of helping the air conditioner cool less, closed registers force the same amount of air through other ducts. This builds pressure in the system and makes your HVAC system work harder to distribute the air where you need it.
If you haven't suffered from moisture issues, you can attempt to close these vents. Remember that if this is a bedroom, you'll need to crack a window at night instead; otherwise, you'll have condensation running down the window by morning. This condensation enters the window frame and begins the decay process.