Can I Vent A Portable AC Into The Cold Air Return?

The most crucial thing you must do for your portable AC to work properly is to vent it. One of the best options is for you to vent it out a window. But what if there is no window around? Can you vent it into a cold air return? Stay tuned as we present what we found during our research regarding this topic. 

Yes, you can vent a portable AC through the cold air return. However, it's not a good idea. This is due to the increased workload placed on your home's central cooling system. 

Continue reading as we explain why it is a bad idea to vent your unit through a cold air return vent. We'll also give you other options on how to vent your portable AC without the use of a window. We'll also discuss why you need to vent your portable AC, the possibility of venting it to another room, and some tips to maximize its efficiency. 

Portable air conditioner in front of lit window, Can I Vent A Portable AC Into The Cold Air Return?

Why The Need To Vent A Portable AC?

Heat is taken out of the air by air conditioners and transferred to another area. The heat from inside your room is transferred outside when an air conditioner cools it.

Heat will return to your room if your portable air conditioner is not ventilated to another area. As a result, your AC will not be able to cool the room. It can even increase the temperature in your room from before.

Venting your air conditioner also removes moisture from your space in addition to heat. When chilling, air conditioners dry out the air. This moisture is ventilated in part outside of your room.

A mobile air conditioning being used at attic

Why Is It Not Recommended To Vent Portable ACs Through Cold Air Return Vents?

Your home's central air conditioning system receives the heat that your portable air conditioner exhausts via the return vent. To remove this heat from your house, your central air conditioning system will also need to work.

In essence, the unit will make your home's air conditioner work twice as hard to remove heat from the space you are chilling.

If there are no other options for venting straight outside, though, this method might be effective. There shouldn't be any problems if your home's central AC system can remove additional heat.

Venting A Portable AC Through A Window: How To?

The window kit that the manufacturer supplies make it easy to install and vent the majority of portable air conditioners. You can get to a cozier interior area in a short amount of time.

The vent hose adapters, one or two vent hoses, and a window bracket are all components of a typical window kit. Since the typical vent pipe is 4 to 5 feet long, you should install yours close to a window.

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To vent your portable AC to the window, you must follow these steps: 

  • Attach any hose connectors or adapters before inserting the hose.
  • Adjust the window kit so that it is the full length of your window. Trim the window bracket as necessary to provide a tight fit for your window. To secure the window kit, your particular model can have screws. You can then secure the kit in place by closing your window.
  • Next, attach the window kit and the vent hose. Once your model is fitted and properly vented, you may instantly begin cooling. Simply connect it and select your preferences. 

Can You Vent A Portable AC Through A Casement Window?

Yes, you can! Many individuals believe that because their windows are casement or crank out windows, they cannot use a portable air conditioner. Don't worry; you can get through this easily. Simply cut a piece of plexiglass to fit your window, mount it like a screen, and your window will still be able to open. 

Make a hole of 5 inches in the piece of plexiglass near the bottom. The vent pipe is then simply inserted into the hole, and you are ready to go. Furthermore, using plexiglass preserves the view out the window.

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How To Vent Portable ACs Without A Window?

Here are some parts of your home you can use to vent through your portable AC if the room you wish to cool doesn't have a window.


The simplest way to vent a portable AC is through a sliding door or a window. The good news is that systems designed specifically for sliding doors exist to assist you in venting warm air. They are simple to install on your doors, allowing your AC to function.

However, most portable AC hose pipes are typically not very lengthy. The unit must therefore be placed close to the door. The hose line may not be able to exhaust the heated air outside if it is situated too far from the door.

Thankfully, some portable air conditioners have slightly longer hose lines.

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Drop Ceiling

You must drill a hole through the ceiling panel to fit the hose to vent the AC. Make sure you avoid touching the electrical cables and pipes that are located above the ceiling panel in your room.

Run the hose through the hole you just made, then use a silicone sealer to close up the remaining gaps.

To make sure that heat and humidity levels are not too high, you must keep an eye on the temperature and humidity in the ceiling space. Mold will develop in the ceiling area if the humidity is too high.

However, it takes a lot of technical know-how to attach the exhaust line to the ceiling tile. For non-expert homeowners, it can be difficult.

Unused Chimney

Pipe sticking out of the chimney

Venting through a chimney is another efficient approach to exhaust a portable air conditioner in a room without windows. By piping it out through the chimney, you may get rid of the warm air created by your air conditioner.

You must make sure the chimney is not in use, though. Never attempt to vent the unit into a functioning fireplace or chimney for safety concerns. You'll put yourself in a lot of danger.

If you don't use the fireplace, you might want to consider putting the air conditioner inside directly underneath the chimney. The vent hose can then be secured inside the chimney walls to direct hot air upward. The hosepipe can even be raised farther to effectively expel heat.


Portable mobile room air conditioner with hose connected to wall

Making a hole in your wall is yet another excellent method for venting a portable AC. Notably, after all, other methods have failed, the majority of homeowners choose to drill a hole in their walls. It offers a long-term fix for your unit.

You must have the proper equipment to cut a hole in your walls because it could be challenging to undo any mistakes you make. The diameter of the hose tubing for the AC will determine the size of the hole to be drilled. You should also think about how frequently you'll use the opening to vent your portable air conditioner.

Once the hole has been drilled in your wall, thoroughly seal it to keep out debris, pests, and other environmental irritants. The use of silicone caulk is the ideal method for patching the hole. Simply cut the hose's tip at a 45-degree angle, put it inside a caulk gun, and use caulk to seal the area surrounding it on the wall.

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You must take into account where you plan to drill in the wall. An outside wall that has an outdoor air vent should be your first choice.

Finding the safest drilling location is important whether you are drilling through stone, brick, drywall, or wood. Otherwise, you risk weakening the building, particularly if you drill the studs or beams that support it. 

Is It Possible To Vent A Portable AC Unit Into Another Room?

It is possible, although not recommended, to vent a portable AC into another room. Due to a significant thermal imbalance and heat conduction through walls and gaps, the rejection of hot air in a neighboring room would impair cooling effectiveness.

Most units automatically vent moisture, which causes a high humidity level in the outlet room that may encourage the growth of mold and mildew.

One's home may contain different arrangements of rooms. Utilizing the heat from the vent may occasionally be a smart move. Knowing what is at stake and whether it is worth it is preferable, though.

Tips To Maximize The Efficiency Of Your Portable AC

Portable air conditioner

These three tips will help you get the most out of your portable AC unit and have a long, fulfilling relationship with it.

  1. Close any entrances to the room you're trying to cool, including any doors and windows. Additionally, make an effort to get rid of as many heat sources as you can from the space, such as the lights and electronic devices.
  2. Turning on your unit earlier than necessary is the best advice anyone can give you. It is better to put it on when the room is still somewhat cool if it is the only cooling source in the space.
  3. Despite the pre-filter most portable AC include, it is frequently preferable to utilize a different filter. Make sure to change the filters every three months or so.

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Final Thoughts

When deciding whether to vent your portable AC to the cold air return, it is best to ask for an expert opinion from your trusted HVAC professional. 

If you enjoyed this post, you could check out these other articles: 

How Long Can You Run A Portable Air Conditioner Continuously?

Portable Air Conditioner Hose Getting Hot - Is This Ok?

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