Does A Furnace Need A Cold Air Return?

When installing a new furnace, you might wonder if it is necessary to have cold air return. That's why we searched for answers, and here is what we discovered.

Yes, your furnace needs cold air return. The function of a home's cold air returns, though, is frequently disregarded and just as crucial as what supply registers do.

Let's now discuss what is the function of cold air returns and why your furnace needs them. We'll also cover how many cold air return vents your house needs and where to place them. In addition, we'll tackle how to maximize the performance of your cold air return. So keep reading!

photo of a man installer hands installing white colored air vents for furnace on the ceiling, Does A Furnace Need A Cold Air Return?

How Does Cold Air Return Work And Why Do You Need Them?

The airflow in your HVAC system needs to be balanced for your furnace to operate well and to heat your home equally. In other words, the volume of air your furnace "breathes in" and "breathes out" must be equal.

Your furnace may "inhale" the air in your house thanks to cold air returns. When warm air is introduced into a space, the cold air that already exists there is forced into the warm air and then returns.

close up photo of an air vent on the brown carpet on the bedroom floor

Once inside, the air from your cold air returns passes through your ductwork and is delivered back to your furnace where it is heated, filtered, and then redirected to warm your home.

These vents, which are often on the wall, lack a control mechanism that would allow them to open or close their flow. Their function is to let air flow back into the furnace so that it can be heated or cooled. An air inlet, that is. The optimal configuration, allowing for the best circulation and airflow, is if your home has returns in the majority of the rooms.

How Many Cold Air Returns Do Your House Need?

photo of a fine looking clean neat modern minimalist living room of the house

The number of vents you require in each room often depends on the size of your house. You will need more than one vent—at least two—if your space is bigger than 100 square feet to provide enough ventilation. You just need one if the space is smaller.

Additionally, consistent air pressure is produced by having multiple return vents—ideally one in each room, though two or three are still preferable to one.

Your house will be okay if it has one return vent. To ensure appropriate air circulation, keep the doors to each room open. It could be a good idea to install a few more return vents if you ever need to replace some of your ducts.

Where To Place Cold Air Return Vents?

photo of an air vent inside of the modern class minimalist design gentlemen room

Properly placing cold air return vents helps your furnace work efficiently. Here are some tips on where to locate your cold air vent: 

Get To Know Your Heating System

Check the heating system in your house. Understanding the area you are heating is crucial. As mentioned, air input and air output must be equal.

If the furnace's input is lower than its output, pressure will build up within the home and potentially deadly gasses could back up. The air will pass through rooms and downstairs to reach the furnace if the return vents don't have proper spacing. This defeats the aim of a forced air system by generating a draft.

Place Them At The Wall's Lowest Point

photo of a white style vents for furnace on a wood tile floor and light blue wall

Place the lowest point of the interior walls of structures where your cold air return vents should be. The return vent draws cold air from the floor of the room, reheats it in the furnace, and then returns it to the room as warm air.

Return vents don't need to be metal-cased like supply vents do. You can position them in stairwell voids, vertically stacked closets, or wall stud openings.

Where a single return vent serves an entire zone, there should be space under the doors to allow the registers to take air even when they are closed without pressing against the furnace which causes negative pressure in the home.

Put Space In Between The Thermostat And Cold Air Return

Because the cold air draft could result in inaccurate temperature readings, place the cold air return at least 10' away from the thermostat.

Don't Use Them In Bathrooms And Kitchens

Due to the high moisture content in bathrooms and kitchens, exhaust fans should be used to remove the air. Observe local building regulations while installing vents in these rooms.

How To Maximize The Performance Of Your Cold Air Return?

To fully utilize your cold air return vents, you should:

Keep Your Cold Air Returns Clear Form Obstructions

The area around your cold air returns must be free of obstructions to provide optimal airflow. Your cold air returns may not function properly if your registers are blocked by furniture, TVs, or other home items.

Add More Returns If Necessary

Unfortunately, not enough air returns were considered in the design of many homes. Stuffy rooms, uneven warmth, high energy costs, and imbalanced pressure are some prominent signs of this.

What Happens When Cold Air Return Gets Blocked?

Whether on purpose or by accident, blocking your cold air returns can be harmful in numerous ways. If one or more of your returns are denied, the following may occur:

Cause Evaporator Coil To Freeze

The purpose of the evaporator coil is to collect latent heat from air passing over it. The coil's surface temperature may fall below freezing without that incoming air, which would cause moisture and condensation to freeze on the coil.

Increases The Energy Utilization Of Your HVAC System

To overcome the restricted airflow created by obstructions, your blower fan must work twice as hard and use far more energy. If you don't remove the obstruction, you might see a gradual rise in your utility bill over time.

Can Crack Your Furnace

In the blower compartment, a blocked cold air return might lead to the heat exchanger storing too much heat and finally cracking. The furnace may release carbon monoxide into your home's air if the cracks are too big. Usually, a situation like this necessitates a complete system replacement.

How To Identify Cold Air Return Vents?

photo of a man hands checking the air flow coming from the air vents brand new air vents

By activating the system fan and raising your palm or a piece of paper, you may locate return vents. It's a return vent if the paper is drawn toward the vent or if you feel a suction effect.

Additionally, you can physically identify return vents because they are larger and they don't have louvers. 

Cleaning Tips To Keep Your Cold Air Return Efficiently Working 

photo of a man hands wearing pink plastic gloves washing the white dirty air vents cleaning

There is more to keeping your return vents clean than just enhancing the efficiency of your HVAC system. Clean return vents keep your furnace filter fresh longer and limit the number of allergens in your home.

So here is a guide on how to clean the return vents in your home. 

Change The Filter

photo of a man wearing sky blue polo cleaning checking air vents on the ceiling dirty filter

Larger homes generally have the filter right next to the furnace. It's typically placed there for easy access in smaller homes and apartments, with just one huge return.

When your HVAC system is operating, you should change the filter every month. Put the date of any filters that don't have a spot to record it on your calendar so that you'll remember to change them when the time comes.

Regularly Vacuum Clean The Vents

If your HVAC system's vents are located in the ceiling, turn it off and protect any furniture. After using a microfiber duster to remove any debris the vacuum missed, vacuum your vents with a dust attachment.

Do not use water or cleaning chemicals because they will spread the dust and turn it into a paste.

Clean The Vent Covers

Pull the vent covers completely off, then wash them with hot, soapy water in the sink. Use a microfiber cloth, and only let them soak for a brief while. Moreover, avoid rubbing too vigorously to avoid the paint peeling off.

During your deep clean, you'll need to get rid of grease if you burn a lot of candles or have vents in the kitchen. Alcohol used for rubbing quickly and efficiently removes oil.

Final Words

photo of a man installer hands installing white colored air vents for furnace on the ceiling

Without cold air return, your furnace will not work effectively. It is a vital part and plays an important role in balancing the airflow of your HAVC system. 

These return vents are usually located plastered to your house wall's lowest point but they can also be sometimes found on ceilings. Additionally, your house needs at least one of these return vents but it wouldn't hurt to add more if you have a bigger area. 

Finally, consult your trusted HVAC professional to properly guide you on what to do with your cold air return. 

If you're having problems with your return vents, you can check out these articles:

Should Air Be Coming Out Of My Return Vents?

Noisy Air Return Vent? Here's What to Do

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