Finding an air conditioner for side opening window setups can be a challenge in many American homes, especially in apartments, condos, and older houses with sliding or casement windows. This comprehensive guide explores the best options, installation considerations, top products, and essential tips, helping you choose the right cooling solution for your unique window type. Enhance comfort this summer without expensive modifications or permanent installations.
| AC Type | Best For | Key Features | Installation |
|---|---|---|---|
| Portable AC | Sliding/Casement Windows | Flexible, easy to move, vent hose | Window vent kit, no permanent hardware |
| Casement Window AC | Vertical/Side-Opening Windows | Vertical orientation, secure fit | Special frame, some installation skills needed |
| Mini Split AC | Permanent, no window use | Quiet, energy efficient | Professional installation |
| Ventless AC | Temporary cooling | Evaporative cooler, no window vent | Plug and go, best in dry areas |
Why Traditional Window ACs Don’t Fit Side Opening Windows
Traditional window air conditioners are designed for double-hung windows that open vertically. With side opening, sliding, or casement windows, these units simply won’t fit, and attempting to force them can cause leaks, safety risks, or window damage. Homeowners must therefore seek alternatives tailored for non-standard frames.
Types Of Air Conditioners Suitable For Side Opening Windows
Portable Air Conditioners
Portable AC units are among the most popular solutions for side opening windows. These units sit on the floor and use an exhaust hose which vents hot air outside through a window kit. These kits are typically adjustable, making them compatible with vertically sliding or casement windows.
- Easy to Move: Portable, flexible for different rooms or apartments.
- Adjustable Window Kits: Most manufacturers provide kits for both vertical and horizontal openings.
- Minimal Installation: Little or no permanent modification is needed – great for renters.
- Variety of Sizes: Ranging from compact 8,000 BTU units to powerful 14,000 BTU models.
Casement Window Air Conditioners
Casement window ACs are specifically designed for windows that open sideways. They are tall and narrow, fitting perfectly in the vertical orientation of a side-hinged window. Historically rarer in the US, but recent demand has increased options from major brands.
- Vertical Design: Engineered to fit casement/sliding windows with minimal modification.
- Stable Installation: Included mounting kits ensure safety and efficiency.
- Limited Models: Usually available in 8,000-10,000 BTU sizes, suitable for small to medium rooms.
- Window Integrity: No need to permanently alter or remove window panes.
Mini Split Air Conditioners
For those seeking a permanent cooling solution with maximum efficiency, ductless mini split systems are an excellent choice. These require installation of both indoor and outdoor units – no need for a window, making them ideal if you want to retain full use of your side-opener windows.
- No Window Needed: Wall-mounted design frees up window space and view.
- Quieter Operation: Indoor unit is much quieter than window ACs or portables.
- High Efficiency: Lower energy consumption and zoned cooling.
- Professional Installation Required: Not suitable for temporary settings.
Ventless (Evaporative) Coolers
Evaporative (or “swamp”) coolers offer a windowless option. These units do not require venting out a window, but work best in dry climates. They add moisture to the air while lowering temperatures, making them less effective for regions with high humidity.
- No Installation: Unbox, fill water, and plug in.
- Climate-Specific: Ideal for places like the Southwest, less useful in the Southeast or Midwest.
- Lowest Energy Use: Consumes much less power than standard AC units.
How To Choose The Best Air Conditioner For Your Side Opening Window
Measure Your Window
Accurate measurement is crucial. Measure the width and height of the openable portion, as this will determine which models and installation kits will fit. Casement ACs need a vertical clearance of 21-24 inches. Portable AC window kits are usually adjustable, fitting widths between 18 and 48 inches.
Call 888-906-9139 for Free Local HVAC Quotes – No Obligation, Just Savings!
Determine Cooling Needs (BTU Sizing)
British Thermal Units (BTUs) indicate an AC’s cooling capacity. Standard guidelines suggest 20 BTUs per square foot of living space. For example, a 350-square-foot room needs a 7,000 BTU unit. Take into account sun exposure, ceiling height, room use, and occupancy for more precise sizing.
| Room Size (sq ft) | Recommended BTU |
|---|---|
| 150 – 250 | 6,000 – 7,000 |
| 250 – 350 | 8,000 – 10,000 |
| 350 – 500 | 10,000 – 12,000 |
| 500 – 700 | 12,000 – 14,000 |
Power Source And Location
Most portable and casement ACs require a standard 115V outlet, but higher-capacity or mini split systems may need special wiring. Ensure your outlet can handle the extra load and that the AC is positioned to evenly cool the space.
Noise Level
Consider where the AC will be installed. Portable and casement window ACs usually produce 50-60 dB, which is comparable to normal conversation or background music. If you’re sensitive to sound or installing it in a bedroom, seek quieter models or consider a mini split system.
Energy Efficiency
Look for the Energy Efficiency Ratio (EER) or Energy Star label. An EER of 10 or higher is optimal. Modern ACs feature settings like ECO mode and programmable timers to further cut energy use and costs.
Best Portable Air Conditioners For Side Opening Windows
Whynter ARC-14S Dual Hose Portable Air Conditioner
This powerful 14,000 BTU dual-hose portable AC is ideal for rooms up to 500 square feet. Its dual-hose design allows for faster and more efficient cooling, while the adjustable window kit fits both horizontal and vertical openings. Includes a built-in dehumidifier (71 pints/day) and activated carbon filter for better air quality.
Honeywell HL10CESWW Portable AC
This 10,000 BTU model covers areas up to 350 square feet. Its flexible window bracket easily fits most sliding and casement windows. The unit emphasizes quiet, consistent cooling (52-55 dB), programmable timer, and a washable filtration system.
BLACK+DECKER BPACT08WT Portable Air Conditioner
This compact 8,000 BTU portable AC is great for small bedrooms and home offices. It operates quietly and comes with a simple installation kit suitable for windows as narrow as 18″ or as wide as 48″.
Call 888-906-9139 for Free Local HVAC Quotes – No Obligation, Just Savings!
Best Casement Window Air Conditioners
Frigidaire FFRS0822SE Casement AC
This purpose-built 8,000 BTU model is one of the most reliable casement window ACs. Its vertical build is specifically for sliding and crank-out windows, includes a mounting kit, and provides multi-speed fans for adjustable comfort.
KEEPOWN Casement Window AC
Another solid choice for side-opening windows, this 10,000 BTU unit cools larger rooms with a vertical profile and safety locks. Multiple operating modes and remote control make it user-friendly.
Installing An Air Conditioner In A Side Opening Window
For Portable ACs
- Attach the exhaust hose to the AC unit.
- Install the adjustable window kit into the open side-opening window.
- Connect the hose to the window kit panel and seal any gaps with included or aftermarket insulation strips.
- Close the window snugly against the panel for a tight fit and plug in the unit.
Tip: Most manufacturers supply foam or plastic padding to prevent air leaks.
For Casement Window ACs
- Open the window fully and set up the mounting frame (supplied by the AC manufacturer).
- Lift the AC into the window, carefully centering it on the frame and sash bracket.
- Expand and secure the adjustable side panels along the window frame for a tight seal.
- Lock the AC according to the installation manual and secure the window with supplied brackets or locks.
- Plug in the AC, ensuring a dedicated power circuit if required.
Safety Note: Casement window ACs are heavier. Two-person installation is recommended.
For Mini Splits
Mini split installations must be performed by a licensed HVAC professional. These units involve mounting the indoor head, connecting refrigerant lines, mounting the outdoor condenser, and running electrical connections. While more expensive upfront, the efficient cooling and long-term value make them ideal for homeowners not wishing to alter their windows.
Pros And Cons: Air Conditioners For Side Opening Windows
| AC Type | Pros | Cons |
|---|---|---|
| Portable AC | Easy installation, flexible, no permanent alteration | Can take up floor space, requires vent hose management |
| Casement Window AC | Strong cooling, secure window fit, less intrusive than portables | More challenging to install, fewer model options |
| Mini Split | Very quiet, high efficiency, preserves view | High initial cost, professional installation only |
| Evaporative Cooler | Low power, no window venting, easy setup | Depends on climate, less powerful than ACs |
Security And Safety Considerations
Securing your window after installation is crucial, especially at ground-level or in urban settings. Use window stops, locks, or adjustable security bars to prevent tampering. Ensure venting is properly sealed to prevent rain, pests, and air leakage.
Alternative Cooling Options For Side Opening Windows
- Ceiling And Box Fans: Cost-effective for smaller rooms, but less effective in heat waves.
- Whole Room Air Circulators: Modern fans like the Vornado help distribute cooled air from another room where AC is installed.
- Thermal Curtains: Reflect heat during the day and retain coolness at night, reducing AC load.
- Smart Home Integration: Use smart thermostats and sensors to optimize cooling cycles and save energy.
Maintenance Tips For Your AC Unit
- Clean Filters Regularly: Dirty filters block airflow and sap efficiency. Clean or replace every 1-2 months as needed.
- Check Window Seals: Reapply weatherstripping or sealant if gaps appear, particularly after seasonal changes.
- Inspect Exhaust/Vent Hoses: Ensure there are no blockages or pinched hoses, which can impede airflow and cause overheating.
- Schedule Professional Service: For mini split systems, annual check-ups keep your system running optimally.
Frequently Asked Questions: Air Conditioners For Side Opening Windows
Can I Use A Regular Window AC In A Sliding Or Casement Window?
No, regular window AC units are designed for vertically opening windows. For slides and casements, use a specially designed casement window AC or a portable AC with an appropriate window kit.
Call 888-906-9139 for Free Local HVAC Quotes – No Obligation, Just Savings!
Do Portable ACs Cool As Well As Window Units?
When properly vented and sized correctly, portable ACs provide comparable cooling for small to medium rooms. However, they may be slightly less efficient because of exhaust hose heat loss.
Are There DIY Kits For Converting Standard ACs To Side Windows?
Some third-party DIY window sealing kits can adapt regular window ACs, but these modifications often void warranties and can reduce safety. Use products specified for the window style to ensure effective cooling and security.
How Can I Reduce Energy Use With My AC?
Maximize energy efficiency by closing blinds, using ceiling fans, sealing windows, and setting the thermostat to 78°F when home. ECO modes and scheduling features are also helpful for reducing electricity costs.
Can Mini Splits Be Installed In Rented Apartments?
Mini splits generally require landlord permission, plus significant wall modifications. For renters, portable or casement ACs remain preferable unless the building already supports mini split upgrades.
Where To Buy Air Conditioners For Side Opening Windows
Major retailers and online platforms like Home Depot, Lowe’s, Amazon, and Best Buy offer a selection of suitable models. HVAC specialists can advise on mini splits and professional installation. Always check return policies and compatibility requirements before purchasing for your side-opening window.
Future Innovations: Smart AC Solutions For Non-Standard Windows
The market is rapidly evolving as more Americans live in apartments or houses with side opening windows. Expect more cost-effective, energy-efficient, and aesthetically pleasing options—such as smart WiFi-enabled models, quieter operation, and custom-fit installation kits—to continue emerging year after year.