In the heating cycle, blocked cold air returns can cause the heat exchanger inside the blower compartment to store too much heat and eventually crack. If the cracks are too large, the furnace can emit carbon monoxide into your home's air. Such a condition normally requires a complete system replacement.
The engine's combustion relies heavily on air, which mixes with fuel to generate energy. In the absence of a sufficient quantity of oxygen, an engine will not be able to generate power, and it may not even start. Whenever the air filter in your car's engine becomes too clogged, it may start to misfire.
Signs of an air duct clog include: One room in your house is hotter than all the others. Dirty air coming from vents. Unusual spikes in electric bills.
Even one blocked vent in the home can cause an inefficiency in air flow, which means your HVAC system will likely have to work harder to achieve the desired temperature. The result may be a home that is riddled with uneven temperatures from room to room.
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.
Blocking the return air supply to the air handler or blower compartment reduces the amount of air that flows easily into the system. The fan's speed won't slow any more when you close off the returns, and it creates positive air pressure.
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.
Return vents are usually larger than supply vents and are in large rooms in the home. The return vents in your home help equalize the pressure that changes as your HVAC system heats or cools your home. These vents should never be fully closed because closing them off restricts airflow and strains the system.
Return air vents connect to your return ducts, and they're typically larger than supply vents. Again, depending on the design of your ductwork and home, HVAC return vent locations vary but are often in central areas, kitchens, bathrooms, and pollutant-prone areas so as to best collect stale or dirty air.
So how much space does an air return vent need to work properly? Home Inspection Insider explains that an air return vent needs 6-12 inches of space in front of it, and recommends that you do not put large, bulky furniture like couches and bookshelves in front of an air return vent.
Limited Return Air
You will want to check and ensure that the return vents throughout your vent are not blocked. If these vents are blocked, it can lead to a lack of air being pulled back into your system.
If the water backs up and comes out of the pipe, you'll need to take more drastic measures to clear the clog. Plumber's snake: Bring a plumbing snake or auger onto the roof. Run it down the vent until you reach the obstruction.
Because the return air vent works to suck air from a room and back into the ducts, you can try this simple test to see if it is working: take a tissue or thin paper and hold it in front of the return air vent, about 6” away. If the paper is being pulled toward the vent, you know it is doing its main duty.
Decreased Acceleration and Power
One of the first signs of a clogged intake air filter is a noticeable decrease in acceleration and power. If your car feels sluggish or struggles to pick up speed, it could be due to restricted airflow caused by a dirty filter.
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.
Your AC's return air vent is a critical component of an HVAC system and serves several purposes. Not only do return air vents maintain your home's air pressure and filter out debris, they can also serve to save you on energy costs and expenses, which is important here in hot and humid Gainesville, Fla.
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.
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.
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.
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.
So why can one room in your home be colder than others? Blocked or Covered Vents: One of the most common reasons for a cold room is blocked or covered vents. Heavy furniture or objects placed in front of vents can obstruct the flow of warm or cool air.
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.