Every modern DFW home has an HVAC (Heating Ventilation and Air Conditioning) system, but not every homeowner understands how it manages airflow (or, in some cases, even how the system works!)

Cold air returns are crucial to the overall process, effectiveness, and goal of reaching the desired temperature. 

If a return air vent is blocked, whether intentionally or by accident, it can also impact your indoor air quality. It can also cause undue stress and possible damage to your HVAC system itself.

Role of Cold Air Return in the HVAC System

First thing’s first: What is a cold air return system?

The cold air vents–also referred to as return air vents–are the ducts that deliver air into your HVAC system’s air handler. 

In other words, your air returns are what allow your HVAC system to take in or “inhale” the air in your home. These registers capture the air and take it back through your ducts where it passes through air filters on its way to being temperature conditioned. The conditioned air is then pushed back out into your home through the supply vent ducts.

If these air return systems are obstructed, not only will you block the proper airflow and create stuffiness in the rooms of your house, but you will have uneven cooling or heating, lack of proper filtration, and potentially higher energy bills.

Here are reasons you should never block your cold air returns and other ways to avoid potential damage to your system.

Reasons You Shouldn’t Block Cold Air Return Vents

There are many reasons why you shouldn’t block cold air returns in your home. Not only can this be damaging and even detrimental to your HVAC system, but by blocking your vents, you can negatively impact the air quality in your home, leading to increased allergens, germs, and dust in the air. Not to mention a higher energy bill each month!

1. Proper Function of Air Return Affects Performance

All air filtration systems work in a cyclical pattern–air must come in, be filtered then heated/cooled, and go back out in order to work properly. Without having a regular stream of incoming air due to blockage (closed vents, furniture, etc.) the unit is unable to function as it’s intended. 

It’s like running a marathon in the hot Dallas Summer heat while wearing a mask. While certainly possible, it’s not ideal! Your airflow is going to be restricted, and it’s going to affect both your comfort and performance.

As a result, the blower fan has to work even harder to overcome this restricted airflow which can lead to increased energy bills, wear on the parts and eventual (and often early) breakdown of the system requiring ac repairs.

2. Restricted Airflow Can Damage Air Conditioner

If there is a prolonged blockage to the HVAC system’s return airflow, this can actually cause internal parts, like the evaporator coil, to completely freeze. Not only can this lead to water leaking from your AC inside your house, but an expensive breakdown in terms of repairs.

During the cooling months of DFW, the evaporator coil is the part of the HVAC system that absorbs latent heat air flows over the coil. The refrigerant in the coil will absorb this heat transfer, but it needs new air coming in from the cold air return vents to help to keep the system running smoothly.

If those vents are blocked, the incoming air fails to reach the coil, causing the coil’s temperature to drop. When the temperature drops under freezing, moisture and condensation alike freeze on the coil. This affects performance resulting in your AC not being as cold as it used to be, and it can result in a major repair or even replacement of the AC system. This also goes for outside. Many homeowners don’t like looking at their unit. Your outdoor unit also needs to breathe, so consider these tips to properly hide an air conditioner unit outside to avoid restricting its airflow.

3. Negative Effect on Indoor Air Quality

In a forced-air system (which is the standard for most heating and cooling systems in DFW), there is an exchange of hot and cold air that is blown through the air ducts to various rooms in your house. 

As new air flows into your home, the existing air is sucked, removed, filtered, and then pushed back out in a circular cycle. This continues until your home reaches its desired temperature determined by your thermostat in either the Summer or Winter.

However, if your air filters are clogged and/or obstructed, the airflow is limited and it restricts this system process. Furthermore, the dust and debris that is typically filtered out through the heating and cooling process can now cycle back into your air. 

The result is uneven heating/cooling, and the air quality is negatively impacted. This can lead to issues such as chronic allergies, asthma, and other respiratory issues.

Air Return FAQ’s:

What is the purpose of the cold air return?

The cold air return is what allows older air present in your home to enter into your HVAC system in order to be cooled or heated. It is then pushed back out to adjust the temperature in your home. Blocking this process is not only damaging to the system but can result in increased energy bills.

Are cold air returns needed?

Because cold air returns are a part of the cyclical cooling and heating process, yes, they are necessary. Without cold air returns, there would be no return of air to the system which is required for proper temperature regulation and air filtration.

Where do you need cold air returns?

Air returns should be located on every story of your home being heated and cooled. The vents are usually located on (or near) ceilings in the South, but can also be found lower on walls or floors where homes feature a basement or have second and third stories.

Final Thoughts on Blocking Cold Air Return Registers

It’s important to avoid blocking your return air registers in order to keep your systems running smoothly, your airflow consistent and filtered, and, of course, your utility bills down.

You should be a little more intentional about your room layouts, your furniture, and the items you may want to display if your returns are located in a place where they can be obstructed.

A good rule of thumb is to keep any couches, chairs, or other furnishings at least ten inches from your cold air return vents. If you have rugs, drapes, or other hanging/heavy materials, be sure to keep those items away from the vents completely.

You should also regularly check your air filters and change them every 1-3 months, or more frequently if you have pets.

For other suggestions about how to prevent issues with your cold air return vents, including room layouts, installing HVAC systems, or best practices for use, be sure to contact the professionals at Diamond Blue Air.