Can You Use an Air Conditioner Without Putting it in the Window? (4 Options for Your AC Unit)

Window AC units are very common, especially in homes or apartments where a traditional HVAC unit isn’t practical to install or purchase. But, what if you need to install an AC in a room without a window?

Can you use an air conditioner without putting it in the window at all?

You can use a window AC unit without a window if you can find an alternative way to vent the exhaust air from the unit, but these options are far from ideal in the long term. You can vent a window AC unit through an exterior wall, through a door, up through a chimney, or into the attic with some effort. If you aren’t able to make modifications to your walls or other structures, you should consider a portable AC unit instead.

Portable air conditioners are an excellent alternative for those who don’t have window access or wish to avoid the hassle of a window installation. These appliances come with various cooling capacities and user-friendly features, making them a practical choice for many households.

Read on to learn more about the nitty gritty details of each option, the reason why you need to pay attention to the exhaust from a window AC unit, and the potential issues that you will face if you don’t install a window AC unit in the recommended way.

What is the purpose of a window AC unit – how do they work?

Window air conditioners, often referred to as window AC units, are a popular solution for those looking to cool smaller spaces. They are designed to fit into the window of a room, providing efficient cooling without taking up valuable floor space.

When you turn on your window air conditioner, the blower starts, followed by the compressor. The compressor lowers the temperature in the evaporating coils. These coils absorb the heat from your room’s air, which causes the room’s temperature to drop. In addition to cooling the air, the evaporator coils also remove moisture, making the air less humid.

Window AC units consist of two air cycles: the room air cycle and the hot air cycle. The room air cycle focuses on cooling the air inside, while the hot air cycle expels the heat absorbed from the room to the outdoors. This process keeps your room at a comfortable temperature.

Window AC units are typically more affordable than central air systems and are also energy-efficient, making them an ideal choice for those on a budget. Installation is relatively simple, requiring minimal tools and knowledge.

Remember, window air conditioners work best in smaller spaces and may struggle to efficiently cool larger areas. To ensure optimal cooling, carefully consider the size of the room and the capacity of the AC unit before making a purchase.

Why do you have to vent a window AC outside?

Air conditioners, especially window AC units, need proper venting to function efficiently. This is because one of their main functions is the process of removing warm air from your room and expelling it outside.

Here are a few reasons why venting a window AC outside is crucial:

  1. Heat removal: Air conditioners work by absorbing the heat from the room’s air and transferring it outside. An exhaust hose helps to accomplish this task efficiently. If you don’t vent your window AC unit outside, the warm air cannot be expelled, and the temperature in the room will not decrease.
  2. Proper airflow: Ventilation is essential for the efficient operation of the AC unit. The window AC unit needs a constant supply of fresh air to work effectively. By venting the exhaust hose outside, you ensure proper airflow for the unit.
  3. Condensation control: As the air conditioner cools your room, it also removes moisture from the air. This moisture is usually expelled out of the unit through the exhaust hose. Without proper ventilation, the condensed water can accumulate, leading to mold, mildew, and other moisture-related problems.
  4. Energy efficiency: If your window AC unit is not properly vented outside, it will struggle to cool your room and maintain the desired temperature. This extra effort often results in higher energy consumption and increased utility bills.

To ensure the optimal performance of your window AC unit, it’s essential to have a proper ventilation system in place. Venting your window AC outside with an exhaust hose enables efficient heat removal, adequate air flow, efficient condensation control, and maintains energy efficiency.

Potential Problems with Venting a Window AC through Alternative Means

When attempting to use a window air conditioner without an actual window, you might face some challenges in creating an alternative venting system.

Here are some potential problems that could arise during this process.

  • Misdirected airflow: Without proper placement of the exhaust hose, hot air created by the AC unit will just find its way back into the room you are trying to cool, negating the effect.
  • Insufficient ventilation: Creating an alternative venting system requires making sure there’s enough air circulation to release the hot air outside. This could lead to an increased workload for your AC unit, reduced efficiency, and a less comfortable indoor environment.
  • Hose positioning and stability: To ensure the efficient operation of the air conditioner, the exhaust hose should be as short and straight as possible. Long or curved hoses could cause a backflow of warm air, reduce efficiency, or even damage the AC unit due to overheating.
  • Safety concerns: In some cases, making modifications to a window air conditioner or altering the ventilation system could create safety hazards. For example, if you drill holes through walls to vent the exhaust hose, it might put your home’s structural integrity at risk, cause electrical issues, or contribute to water leakage problems.

While it is possible to use a window air conditioner without a window by creating an alternative venting system, it’s essential to consider these potential issues. Evaluate your options carefully and consult with a professional if necessary to ensure that your solution is not only efficient but also safe for you and your home.

Can you use a window AC without a window? 4 Alternatives to consider

Yes, you can use a window air conditioner without a window. Although it’s not as common, there are alternative methods to install your window AC unit.

Here are a few practical options:

  1. Venting through a wall
  2. Venting up through a chimney
  3. Venting into the attic
  4. Venting through an exterior door

Keep in mind that none of these solutions (except maybe the wall option) would be considered a permanent way to install your window AC unit but they could all be used in a pinch if you don’t have any other options.

In general, it would be best to consider replacing your window AC unit with a portable AC unit that is meant to be used indoors and has additional options for venting.

Remember, regardless of the method you choose, safety and maintaining the efficiency of your air conditioner are crucial. It’s essential to follow the manufacturer’s guidelines and consult a professional if you’re unsure about any of the installation steps.

Below is a table that summarizes the key points from the article for easier reference:

Venting MethodKey ConsiderationsLongevityChallenges & RisksSkill Level Required
Venting through a wallClose to electrical outlet, non-obstructiveLong-termRequires professional installation, may violate building codes, drainage & moisture concernsHigh
Venting up through a chimneyChimney should not be in use for other purposes, near an electrical outletTemporaryCould result in inefficiencies, hazards like carbon monoxide build-up, and may violate codes or void warrantyMedium
Venting into the atticAdequate attic ventilation, run hose to attic without obstructionsNot AdvisableMay lead to moisture, mold, structural damage, potentially violates building codes, efficiency may be compromisedMedium
Venting through an exterior doorClose to an electrical outlet, easy access for maintenanceTemporaryMust keep door closed for efficiency, sealing challenges, condensation drainage requiredMedium


  • Key Considerations: Factors to consider when selecting the venting method, such as location requirements and usability.
  • Longevity: How sustainable is the venting method over a long period.
  • Challenges & Risks: Potential problems or hazards associated with each venting method.
  • Skill Level Required: The level of technical skill required to implement each venting method.

Each venting method has its own set of challenges and considerations. It’s important to follow safety guidelines and consult professionals when uncertain about installation steps.

Vent your window AC unit through a wall

Installing a window AC unit in a room without a window by venting it through a wall is possible but comes with several challenges.

Venting a window AC through a wall is complex and may require professional installation, potentially violating building codes and voiding the unit’s warranty. Drainage and moisture control are also concerns, and the alteration may compromise the wall’s structural integrity and insulation. The cost can be higher than other cooling options designed for rooms without windows. Electrical placement and outdoor space limitations should also be considered.

If you have the skills necessary to do this, installing a window AC unit in the wall is actually a pretty viable option, even in the long term. However, it will require a pretty significant amount of skill and effort.

Given these factors, alternative cooling solutions like portable AC units or ductless mini-splits might be more practical.

How to vent your window AC through a wall

Yes, you can use a window air conditioner without placing it in a window if you vent it through a wall. Here is a step-by-step guide on how to do so:

  1. Choose a suitable location: Pick a spot in your room where you want to install the air conditioner, keeping in mind that it should be close to an electrical outlet and not obstruct any doorway or window.
  2. Measure and mark the wall: Measure your window AC unit’s dimensions and mark the outline on the wall where you want to install it. Don’t forget to leave some space around the outline for proper insulation.
  3. Cut the hole: Use a saw to carefully cut the marked outline on the wall. Make sure to wear proper safety gear like gloves and goggles while cutting.
  4. Install a support frame: Build a wooden frame that fits the hole snugly and secure it to the studs in the wall using screws.
  5. Insert the air conditioner: Carefully place the window AC unit into the hole and secure it to the support frame with appropriate brackets and screws.
  6. Seal the gap: Insulate the gap between the wall and the air conditioner using foam weatherstripping to prevent drafts and energy loss.
  7. Attach the ventilation duct: Connect a ventilation duct to the exhaust of the air conditioner and route it to the other side of the wall or the outside. Secure the duct with clamps and seal any joints using duct tape.
  8. Install an exterior vent cover: To protect your duct from weather and debris, install a vent cover on the other side of the wall where the duct exhausts the hot air.

Remember to follow the manufacturer’s instructions and safety guidelines while installing the air conditioner.

Vent your window AC unit up a chimney

Venting a window AC unit up a chimney is generally not recommended, but it could be possible in a pinch.

Chimneys are designed for a specific purpose—venting hot gases from a fireplace or furnace—and modifying this system for an air conditioner could result in inefficiencies or even hazards like carbon monoxide build-up if the chimney is also being used for its original purpose. Additionally, you could face issues with moisture control and potentially violate local building codes or void the AC unit’s warranty.

How to vent your window AC up a chimney

If you have a window AC unit and are hesitant to install it in a window, you may have other options, such as venting it up a chimney.

  1. Inspect the chimney: Check for any obstructions, debris, or buildup. If the chimney is not in good condition or is being used by other appliances, such as a water heater or furnace, do not proceed.
  2. Measure and prepare: Measure the diameter of the exhaust hose on your window AC unit and purchase a flexible vent hose of the same size. Also, gather tools and materials such as wire, a ladder, and gloves for safe installation.
  3. Install the chimney vent connector: Attach the flexible vent hose to the exhaust port on your window AC unit. Secure it tightly with the provided clamp or zip tie.
  4. Position the AC unit: Place the window AC unit on a stable surface near the chimney. Make sure it’s level and secure. If necessary, use a support bracket to hold the weight of the unit.
  5. Route the vent hose up the chimney: Carefully feed the vent hose up the chimney until it reaches the flue vent. Attach the vent hose to the flue vent using a piece of wire to ensure the warm air from the AC unit can be easily exhausted up the chimney.
  6. Secure the vent hose: Double-check the vent hose connections and make sure they are secure. Ensure the hose isn’t kinked or obstructed, which could impede airflow.
  7. Turn on the AC: Plug your window AC unit into an outlet and test its functionality. It should be able to efficiently cool the room while the warm air is vented up the chimney.

Keep in mind that this setup is more suitable for those who do not intend to use the chimney for its original purpose, as utilizing both the fireplace and AC vent at the same time could cause issues.

Vent your window AC unit into the attic

Venting a window AC unit into an attic is not advisable for several reasons.

First, the hot air expelled by the AC unit will accumulate in the attic, potentially leading to issues with moisture, mold, and even structural damage. Second, this method of venting could violate local building codes and void your AC unit’s warranty.

Finally, because attics are typically not well-ventilated areas, the efficiency of the air conditioner will likely be compromised, making it a less effective and potentially more costly cooling solution.

How to vent your window AC into the attic

To effectively vent your window air conditioning (AC) unit into an attic, follow the outlined steps below:

  1. Measure the ventilation space: Ensure that there is adequate ventilation in the attic to handle the hot air expelled by the AC unit. Insufficient ventilation can result in poor performance, so make sure your attic is large enough to accommodate the hot air.
  2. Determine the hose route: Plan a route to run the exhaust hose from your AC unit to the attic, ensuring that there are no obstructions or sharp bends.
  3. Install a duct or vent: There may be existing vents in your attic that can be reused to help facilitate airflow. If not, you may need to install a new vent or duct, making sure it is properly sealed and insulated to prevent air leakage and heat transfer.
  4. Secure the exhaust hose: Run the exhaust hose from the AC unit to the vent or duct in the attic. You’ll want to make sure it’s properly secured, keeping in mind any bends or turns in your hose route.
  5. Monitor attic temperature: After installation, it’s crucial to monitor the temperature in your attic on hot days. Extremely high temperatures can negatively impact the performance of your AC unit and potentially lead to damage. If needed, consider adding additional ventilation or insulation.

By venting your window AC unit into the attic, you can effectively use it without placing it directly in a window. Just ensure that the necessary steps are taken to establish proper ventilation for optimal performance.

Vent your window AC unit through an exterior door

Venting a window AC unit through an exterior door or a doggy door is technically possible but comes with some challenges.

The door will need to remain closed to keep the unit operating efficiently, which could be inconvenient. Additionally, there may be issues with sealing the exhaust properly, leading to inefficiency and potential loss of cool air. You’ll also need to ensure proper drainage for any condensation created by the unit.

How to vent your window AC through an exterior door

  1. Find the right location: Choose an exterior door that is near a power outlet and can be easily accessed for installation and maintenance. Avoid using front doors that could create safety concerns or inconvenience for household members and guests.
  2. Measure the door: Measure the width and height of the chosen door to ensure your window AC unit will fit properly. Be sure to account for any door molding or trim when making these measurements.
  3. Purchase necessary materials: You’ll need a venting kit, insulation materials, and additional tools for this project. Venting kits are available online or at local hardware stores and should include a hose, vent, and attachments. Make sure the kit is compatible with the size of your AC unit and door measurements.
  4. Create an opening: Follow the venting kit instructions to properly cut an opening in your door. This may require the use of power tools and assistance from another person for safety and precision. Always wear protective gear when using power tools.
  5. Install the vent: Secure the vent according to the kit instructions, then connect the hose to the window AC unit. Ensure the connection is tight and secure to prevent air leakage.
  6. Insulate the opening: Properly insulate the opening around the vent to prevent drafts and improve energy efficiency. Insulation materials may include weatherstripping, foam, or caulking, depending on the door type and specific project needs.
  7. Secure the AC unit: If necessary, find a method to secure your window AC unit near the door to prevent it from tipping or shifting. Some creative solutions might include using a small table, shelf, or custom-built support structure.

By following these steps, you can effectively vent your window AC unit through an exterior door without having to install it in a window. Remember to periodically check and maintain your vent setup to ensure optimal performance and energy efficiency.

Would portable air conditioners or a windowless air conditioner make more sense?

In most cases, it would make more sense to use a portable air conditioner rather than trying to adapt a window AC unit for a room without a window.

Portable AC units are designed for more flexible placement and typically come with kits that allow you to vent the exhaust through a smaller hole in a wall or even a door. They are generally easier to install and remove, making them more versatile for different living situations.

Using a portable AC avoids many of the challenges and potential code violations associated with modifying a window unit, such as compromised efficiency, moisture control issues, and voiding the warranty.

Overall, a portable air conditioner is usually a more practical and less complicated solution for cooling a room without a window.

Important Aspects of Heating and Cooling Efficiency for Window AC Units

BTU Ratings

BTUs (British Thermal Units) gauge your window AC’s cooling capacity. Higher BTUs mean more cooling power. For a 100-square-foot room, aim for a 5000 BTU unit; a 250-square-foot space needs around 8000 BTUs.

Climate Control Features

Look for adjustable fan speeds, temperature settings, and air-flow direction to optimize comfort and efficiency. Some units also offer heating modes for year-round climate control.

Energy Efficiency

Check the SEER (Seasonal Energy Efficiency Ratio) and EER (Energy Efficiency Rating) to assess the unit’s energy performance. Higher ratings equal better efficiency and lower utility bills. Units with the “Energy Star Most Efficient” label can cut energy use by up to 50%.

When choosing an AC unit, prioritize BTU rating, climate control features, and energy efficiency indicators like SEER and EER to maximize comfort and cost-efficiency.

Important Maintenance and Safety Tips for Window AC Units

Filter and Water Reservoir Maintenance

It’s essential to keep your window AC unit’s filter clean for efficient performance. Be sure to remove the filter and wash it in warm, soapy water monthly when the unit is in use. Additionally, some units have a built-in dehumidifier with a water reservoir that needs emptying periodically. Make sure to clean the condenser coil and fins to remove any dust or debris that may have accumulated, ensuring proper airflow.

Safety Measures for Use

Your safety while using a window air conditioner is crucial. Follow these guidelines to minimize risks:

  • Unplug the unit: Always unplug your AC unit before performing any maintenance to avoid electric shock.
  • Proper installation: Ensure that the AC unit is securely and correctly installed in the window to prevent it from falling out and causing accidents.
  • Avoid overheating: Keep the area around the compressor and condenser coil well-ventilated to avoid overheating, which could lead to a refrigerant leak or other malfunctions.
  • Inspect cords: Regularly check the power cords for any signs of wear or damage, and replace them if needed.

Dealing with Noise

Window AC units can produce noise from the compressor, fan, and other internal components. To reduce the noise level:

  1. Ensure the unit is correctly installed and tightly secured to minimize vibrations.
  2. Keep the filter clean and maintain proper airflow to prevent the unit from working harder, causing increased noise.
  3. If the noise persists, consider bringing your unit to a professional for inspection and possible repairs.

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