Can You Vent A Portable AC Into The Attic? All You Need To Know

Controlling the climate of an attic can be difficult. This is especially true if it’s the summer or if you live somewhere with a particularly warm climate. It’s also true that attics are often the most neglected room of a house – being left for long periods of time without being cared for. This is fine most of the time, but certain climate conditions can cause issues in your attic, and you may want to control the temperature up there. But what if your attic isn’t connected to your house AC? Or what if you don’t have a house AC at all? 

Can You Vent A Portable AC Into The Attic

That’s where portable ACs come in. These little machines are perfect for moving from room to room in your house and giving attention to whatever space in your house that you need. But here’s the thing – can you vent a portable AC into the attic to get rid of this hot air? If you’re wondering about this, then you’ve come to the right place!

We’ve compiled a total guide of everything you’ll need to know in order to get the best out of your portable AC. We’ll take you through some of the risks, common mistakes, the pros of portable ACs, and how you can tackle additional issues such as mold and dust. We’ve also made sure to include an extensive FAQ section that is going to take you through some other questions related to this issue.

Let’s get into it!

What Is Meant By ‘Venting an AC?”

When we talk about venting an AC, what we mean is taking the cold air coming out of the unit and blowing it outside. There are several different ways that you can do this. Some units are designed to be vented directly out of the back of the unit (this is called direct vent). Others are designed to be ventilated through ductwork (called indirect vent). Let’s look at both options.

Direct Vents

A direct vent is one of the most popular types of vents available. Direct vents are usually found on smaller units and are designed to be installed directly onto the wall of your home. When you install a direct vent, you simply remove the cover plate from the back of the unit and insert it into the opening. Then you screw the unit into place.

Indirect Vents

Indirect vents are also fairly common. These vents are often used on larger units because they’re much easier to work with. Instead of installing the unit directly against the wall, you typically run ductwork from the unit to the exterior of your home. Once the ductwork is connected to the unit, you attach a filter to the intake side of the ductwork. This allows the air to flow smoothly through the ductwork without being blocked by debris or other objects.

Why Is Venting Important?

Now let’s talk about what happens when you don’t vent your portable air conditioner properly. When you run a portable air conditioner without proper ventilation, you’re basically trapping all of the heat inside your attic.

As you can imagine, this isn’t good for anyone. Not only does it mean that you’re wasting energy, but it also means that you’re creating a breeding ground for bacteria and mold. Both of these things can cause serious health issues for you and your family. That’s why it’s important to make sure that you vent your portable air conditioners correctly.

How Do I Install A Portable Air Conditioner In My Attic?

Installing a portable air conditioner isn’t as hard as some people think. But it does require a little bit of planning ahead of time. First off, you need to know where you plan on placing the unit so that you can get it there safely. Next, you need to decide whether you want to go with a direct vent or an indirect vent. Finally, you need to figure out how you’re going to connect the unit to the ductwork. We’ve got all the information you need right here!

The Best Place To Put Your Portable AC

The first thing you should consider when deciding where to put your portable air conditioner is safety. Make sure that you don’t block any windows or doors in your home. Also, keep an eye out for any electrical outlets that may be nearby. If there’s anything near those areas that might cause damage to the unit, move it away until you can find another spot.

Do I Want An Indirect Or Direct Vent?

Once you’ve decided where you want to put the unit, you need to make a decision regarding which type of vent you want to use. Both direct and indirect vents come in many sizes and styles, but each has its pros and cons. Let’s take a closer look at them.

Direct Vs. Indirect Vent

The main difference between direct and indirect vents is that indirect vents allow more airflow than direct vents. That means that if you have a large space, you may not even need a direct vent. However, if you have a small space, you will probably need a direct vent.

Which One Should I Use?

If you live in a very hot area, then you’ll likely benefit from using an indirect vent. They tend to provide better cooling performance than direct vents. On the flip side, direct vents are generally cheaper than indirect vents. 

How To Connect Your AC To The Ducts 

Now that you’ve chosen your vent style, you need to determine how you’re going to attach the unit to the ducts. Most manufacturers offer two different methods for connecting the unit to the duct: drop-in and pop-up.

Drop-ins are pretty easy to install. Just slide the unit into the ducts and tighten the screws. Pop-ups are slightly harder to install. You need to cut the ducts down to size before attaching the unit. Then, you simply snap the unit onto the end of the ducts.

How Does Your Portable Air Conditioner Work?

The main function of any portable air conditioner is to provide you with comfortable indoor conditions. It does this by removing heat from the surrounding environment through evaporation.

The process involves passing refrigerant over a coil which causes it to change state from gas to liquid. When the refrigerant changes state, it absorbs heat from the surrounding environment. As the refrigerant evaporates, it releases heat into the surrounding environment.

This heat is then removed by the outdoor unit. If you are venting this heat into your attic, there are factors to take into consideration.

Why A Warm Attic Can Cause Problems

You Have An Old House With A Hot Attic

This is another reason why you’d want to use a portable air conditioner in your attic. If your attic gets too hot, you could end up having problems with things like mold and mildew. And these aren’t only problems for older homes either. They can happen on newer houses too depending on the weather/climate and how the house has been cared for. 

Mold and Mildew

Mold and mildew are two very serious health hazards that can occur in any area of your home. They can grow quickly and spread throughout your entire property. Mold is a common cause of health problems, including breathing conditions such as asthma. It can be detrimental to the health of your family, so it’s very important to try and fix it as quickly and effectively as you can. 

Mold and mildew can even affect the structural integrity of your roof. So if you notice any signs of them appearing in your attic, make sure to contact a professional immediately. 


Another problem that can arise in your attic is dust. Dust particles can easily enter your attic through cracks and holes in the walls and can start building up over time. This dust can eventually turn into a thick layer of grime that can collect on everything in your attic. If you leave your attic shut up for too long like this, you’ll have a hell of a time trying to clean it out on your own. Air conditioning can help you to remedy this problem, or stop it before it starts.

Portable air conditioners should be vented properly to prevent heat buildup in attics. The importance of venting adequately is extremely important if your attic is small and not well ventilated.

In this scenario, your attic could already be leading to a higher home temperature which will require your AC unit to work even harder to bring the temperature of your home down. 

Without adequate attic ventilation, the internal temperature within your attic could increase to as much as 50 degrees over the desired temperature.

By adding ventilation from your AC unit to this environment, this internal temperature will increase further and could cause significant structural damage to your home.

What Are Some Other Things To Consider When Installing A Portable Air Conditioner?

There are other considerations that you should make when installing a portable air conditioner. For example, make sure that you buy a model that meets local building codes. This way, you won’t have to worry about getting fined by the city for breaking the law.

Also, make sure that you choose a model that comes with a warranty. Many models do, so check online to see what kind of warranty they offer.

Finally, make sure that you read through the owner’s manual thoroughly before installing the unit. There could be some helpful tips that you didn’t realize were included.

Attic Humidity Levels And Self-Evaporating Portable Air Conditioning Units

Self-evaporative portable air conditioning units are an efficient method of cooling because they capture moisture in the room and expel it out with hot air through the hose that runs them.

Air conditioners that are partially evaporative are more efficient than those that are fully evaporative. 

If you use a portable air conditioner and don’t vent it properly, you could end up ruining your attic. Air conditioning units suck air from outdoors. This means that if you have a window open, there might be some fresh air coming in.

However, this does not mean that you should always leave your windows open. In fact, it is better to close them as much as possible. You also need to make sure that you do not let any moisture enter your house. Moisture can cause mold growth inside your home.

Single Hose Portable Air Conditioners operate by sucking air from inside the room and cooling the refrigerant in the condenser. Then, the air is exhausted out of the vent hose.

Dual Hose Portable Air Conditioner operates by sucking air from both sides of the room and cooling the condenser. Then the air is exhausted out through both the vent hoses.

If you’re venting to an attic, then you will expel this humidity into your attic space which could cause issues. It is only advisable to vent your AC unit into an attic space if the unit doesn’t have self-evaporative technology. 

Similarly, if there is no option for humidity to be removed via the vent hose then this method of ventilation shouldn’t be used.

The only time when a partial or fully evaporative portable air conditioning unit can be vented into your attic is if the unit is able to remove water vapors produced and ventilate them efficiently.

Excess humidity exhausted into an attic space can cause severe health problems through the growth of mold and the presence of dampness. Mold can spread very quickly and could soon spread to spaces outside of your attic.

Breathing in mold can cause respiratory illnesses, allergic reactions, and affect our immune systems. 

For these reasons, it is imperative to not expel ventilation from your portable air conditioning unit into the attic space if your unit is unable to ventilate effectively, or if your attic space is particularly prone to high humidity.

Is Your AC Hose Length Suitable For Attic Ventilation

Your portable air conditioning unit will be supplied with a vent hose that is compatible with your machine and specifically designed to encourage efficiency and effective use.

For this reason, you should be careful while extending them beyond the recommended limits as this could alter their effectiveness and efficiency. It could also lead to damage where your hose would need to be repaired or replaced in its entirety.

It is important to make sure that the distance between your room and the attic is within the recommended range of the hose.

If it is, then there is no problem with extending the hose, as long as you have already addressed whether you have adequate ventilation options in your attic. 

If you have humidity and temperature complications in your attic, you should not ventilate in the attic even if your hose length fits!

It is important to check the maximum extendable length of the unit before using it. These vary on average between 5-7 feet in length. However, this can vary from unit to unit so it is important to check your own instructions for guidance.

If you are going to extend your hose to vent into your attic, it should be used with care to encourage efficiency and minimize damage. 

You should never over-extend it too long and not make sharp 90 degree bends in your hose. This will significantly reduce the effectiveness of your AC unit’s operation.

What Other Ways Can You Vent Your Portable AC Unit

Can You Vent A Portable AC Into The Attic (1)

If you have concluded that venting your portable air conditioning unit to your attic is not a suitable option, then fortunately there are many different ways to vent a portable AC.

Most commonly, the unit comes with a window venting system. Once the unit is placed near a window, you pass the venting hose through the window.

To vent an air conditioner through a window, you need to be careful about safety as you may have difficulty locking the window with the hose positioned.

Each AC unit will have its own guidance on how to do this securely depending on the type of hose attached to your unit.

If this method doesn’t work, there are also other options available to you.

To vent your AC you could also ventilate via your chimney or through your floor. You could also use a drop ceiling technique to make a hole in the ceiling. 

Whilst some of these alternative techniques are not straightforward, the moral here is that if the straightforward route doesn’t work for you, there are other options available.

Solutions For Attic Spaces With Temperature And Humidity Problems

Your attic should be cool in winter and hot in summer. You need to make sure that there is enough ventilation in your attic to maintain these temperatures throughout each season.

Ensuring adequate ventilation will help to prevent mold and mildew. Mold and mildew can damage your house and also cause a range of health issues if inhaled. 

It is therefore imperative that you make sure you have sufficient insulation in your attic, particularly if you are looking to vent your AC machine into it.

However, there are some simple solutions available to create a temperature-controlled and humidity free attic space:

Natural Ventilation

Adequate insulation prevents heat transfer from the attic to other parts of your house. Natural ventilation is a common option to naturally vent your attic to let some of the hot air out and maintain an adequate temperature within your loft.

This could be done by installing vents near the top of your roof to expel hot air. These vents will also naturally allow cool air to enter the attic to increase ventilation and create a consistent temperature within your attic. 

Powered Ventilation

Fans create airflow by moving air around. When you use fans, you need to make sure that there is enough space for them to move so they can circulate fresh air into the space adequately.

There are two main options for powered ventilation. These are generally gable or roof-top fans. Roof-top fans blow hot air out of the attic while replacing it with cooler air. Two gable fans blow cool air into the attic.

Frequently Asked Questions

How Can I Measure Humidity Levels?

Humidity levels play a huge role in determining whether or not you need to add humidity control to your room. In fact, high humidity levels can actually lead to mold growth. So, if you know that your house tends to get really humid during certain times of the year, you’ll want to invest in a dehumidifier.

However, if you only have occasional issues with humidity, you shouldn’t bother buying one. Instead, focus on keeping the air circulating throughout your house.

How Much Does A Portable Air Conditioner Cost?

As mentioned earlier, prices vary greatly depending on the brand and features of the unit. However, you can expect to pay anywhere from $100 to $1,000 or more for a quality unit.

You also need to keep in mind that the price will go up after you purchase it. That is because you’ll need to buy additional accessories like filters and fans.

Are Portable Air Conditioners Safe?

Yes, absolutely. While they aren’t designed to withstand extreme temperatures, they are built to withstand regular use. And, even though they don’t come with warranties, many units include extended warranties.

The bottom line is that these units are safe enough to use around children.

Is It Worth Having An Indoor Unit?

It depends on your situation. If you have a small apartment, you probably wouldn’t notice much difference between having an indoor unit and an outdoor unit. But, if you have a large home, you may find that an indoor unit would provide better cooling.

Can I Vent My AC Unit Through the Window?

There are times you might not have the option to vent your AC through your attic and would look to vent via a window instead. Whilst this option is usually straightforward,  it might not be possible for you.

The distance of your unit to your window, the length of your hose, and whether you are still able to close your window, will all play a contributing factor on whether you can vent your AC unit through your window.

If window ventilation is not possible, there are alternative options available such as through a chimney or floor.

What Size Attic Do You Need To Vent A Portable AC Unit

There are many considerations to take into account when deciding if you can vent your portable AC unit through your attic. The size of your attic will also play a large role.

If your attic space is too small, then humidity and temperature control may be an issue. 

Generally speaking, your attic space will need to be large enough to adequately ventilate and control the temperature and humidity of your house, without the additional demands of your AC unit.

Can You Use A Portable Air Conditioner In A Small Room?

In short, yes you can! However, there are a few things to consider before doing so.

Firstly, you should ensure that your room has adequate natural ventilation. This means ensuring that windows are open and that doors are closed. If you do not have access to natural ventilation, you will need to install a fan.

Secondly, you should check that your room does not exceed the maximum recommended indoor temperature set by the manufacturer of your air conditioner.

Thirdly, you should ensure that the room is well insulated. Insulation helps prevent heat transfer between rooms. This will enable you to use your unit efficiently and effectively.

Final Thoughts

So as we can see from this article, there are many factors to take into consideration before deciding to vent a portable air conditioning unit through an attic.

As you can tell, there are a lot of individual factors to take into account to work out the most efficient way of achieving this.

The complications of venting your portable air conditioning unit through your attic can be significant if undertaken incorrectly. 

High internal temperatures within your attic from inadequate ventilation can cause structural damage to your woodwork and roof tiles.

An increase in humidity can lead to damp issues within your attic and mold growth which can quickly spread throughout your home and cause health complications if inhaled.

Through this article, we have discussed the options available to you when looking to vent your portable air conditioning unit. We have armed you with the tools and information so you can now make the right choice for you.