Quick Answer: If your window cranks or slides open instead of raising up, most window ACs simply won’t fit — you need a dedicated casement/slider unit. The Frigidaire FFRS1022R1 (10,000 BTU nameplate, ~$499–649) is the best overall pick and the easiest to find in stock. The Koldfront CAC8000W (8,000 BTU, ~$410–559) is the quietest and most efficient. Before you buy on BTU alone, know this: several of these units’ real DOE-rated cooling capacity runs far below their nameplate number — check the spec sheet, not just the box.
Casement, crank-out, and horizontal sliding windows are the one category a normal window AC can’t solve. There’s no sash to slide the unit into and no sill for it to rest on, so a standard window unit has nothing to seal against. We rounded up the dedicated casement/vertical window air conditioners that actually work in these openings, and the one spec most sites skip: the gap between the advertised BTU and the number the DOE actually certifies.
Casement AC facts, by the numbers
| Metric | Figure | Source |
|---|---|---|
| Frigidaire FFRS1022R1: nameplate vs. DOE-rated BTU | 10,000 nameplate / 5,100 DOE | Home Depot product listing |
| Koldfront CAC8000W efficiency | 11.0 EER, Energy Star certified | Koldfront spec sheet |
| Typical casement AC price premium vs. standard window unit | ~$150–300 more at the same BTU | Retailer pricing (Home Depot, Walmart, Sylvane) |
| Typical cabinet width for a casement/vertical unit | ~15–16 inches, adjustable panels up to ~3 ft tall | Manufacturer install guides (Koldfront, Frigidaire) |
The single biggest gap in this category shows up on the spec sheet, not the showroom floor: Home Depot’s own listing for the “10,000 BTU” Frigidaire FFRS1022R1 shows a DOE-rated cooling capacity of just 5,100 BTU — less than half the number in the product name. That’s because the DOE’s newer test procedure accounts for heat the unit itself adds back into the room, and casement units — with their narrower, taller cabinets — often take a bigger hit than standard window ACs of the same class. It’s the same “nameplate vs. real” gap this site tracks for portable ACs (SACC vs. ASHRAE), just less talked about here. Shop the DOE number when a retailer publishes it.
Our top picks at a glance
| Unit | Best for | Nameplate BTU | Efficiency | Price |
|---|---|---|---|---|
| Frigidaire FFRS1022R1 | Best overall / easiest to find | 10,000 | CEER ~9.4 | ~$499–649 |
| Koldfront CAC8000W | Quietest + most efficient | 8,000 | 11.0 EER, Energy Star | ~$410–559 |
| Soleus Air Exclusive Series | Best value | 8,000 | CEER 11.5, ~47 dB | ~$420 |
| Perfect Aire 4PASC10000 | Best for larger rooms | 10,000 | R-32, 450 sq ft rated | ~$500–540 |
1. Frigidaire FFRS1022R1 — Best Overall
Frigidaire FFRS1022R1 (10,000 BTU nameplate)
- The most widely stocked dedicated casement/slider window AC, with adjustable side panels for a range of window widths.
- Nameplate 10,000 BTU, but Home Depot's own DOE-rated listing shows 5,100 BTU real-world capacity — size your room off that number.
- Included remote with digital thermostat, on par with Frigidaire's standard window-unit controls.
Don’t sweat the heat wave — Prime delivers your portable AC in two days. Try it free for 30 days.
The Frigidaire FFRS1022R1 is the default pick for a casement or sliding window because it’s the one you can actually buy — this category has far fewer models and far less retailer stock than standard window ACs, and Frigidaire’s slider/casement line is the one that shows up reliably at Home Depot, Walmart, and Sylvane. The catch is the BTU math: don’t size your room off the 10,000 in the product name. Home Depot’s own spec listing certifies it at 5,100 DOE-rated BTU, which is a meaningfully smaller room than the nameplate number implies. Treat it like an 8,000-BTU-class unit when you’re deciding if it’ll cool your space, not a true 10K. Our Frigidaire lineup guide covers the rest of the brand’s window and portable models if this one doesn’t fit.
2. Koldfront CAC8000W — Quietest + Most Efficient
Koldfront CAC8000W (8,000 BTU)
- 11.0 EER and an Energy Star certification — the most efficient dedicated casement AC we found.
- Runs quieter than the Frigidaire on paper, with a built-in dehumidify mode.
- Availability and pricing swing hard between retailers — confirm current stock before you commit to it over the Frigidaire.
If efficiency and quiet running matter more to you than raw availability, the Koldfront CAC8000W is the better casement AC. An 11.0 EER and Energy Star badge are genuinely strong numbers for this specialized a category, and it adds a built-in dehumidify function the Frigidaire doesn’t emphasize. The tradeoff is that Koldfront’s casement line has less consistent retail stock than Frigidaire’s — prices we found ranged from about $410 at big-box retailers up past $550 elsewhere, so shop around and confirm current availability before you plan a purchase around it specifically.
3. Soleus Air Exclusive Series — Best Value
Soleus Air Exclusive Series (8,000 BTU)
- CEER 11.5 and a rated ~47 dB — competitive efficiency and noise for meaningfully less than the Frigidaire.
- Same adjustable vertical side-panel install as the rest of this category.
- Smaller brand than Frigidaire or Koldfront, so parts and support are less established.
The Soleus Air Exclusive Series undercuts both the Frigidaire and the Koldfront on price while still posting a competitive 11.5 CEER and a quiet ~47 dB rating. It installs the same way as every unit on this page — adjustable vertical panels filling the fixed section of the window frame — so you’re not giving up functionality, just brand recognition. Worth a look if you want the efficiency of the Koldfront without quite the price tag, and you’re comfortable buying a less household-name brand.
4. Perfect Aire 4PASC10000 — Best for Larger Rooms
Perfect Aire 4PASC10000 (10,000 BTU)
- Rated by Perfect Aire for up to 450 sq ft, the largest coverage claim of the units here.
- Follow-Me remote sensor reads temperature from where you're sitting rather than at the unit.
- R-32 refrigerant, in line with the newer, lower-GWP standard other brands are shifting to.
If your casement or slider window is cooling a bigger space — a converted sunroom, an open living area — the Perfect Aire 4PASC10000 carries the largest manufacturer coverage rating in this guide at 450 sq ft. Like the Frigidaire, check for a DOE-rated figure before you rely on the nameplate 10,000 BTU number; Perfect Aire doesn’t publish one as prominently as Frigidaire’s retailers do, so size conservatively. The Follow-Me remote is a genuine nice-to-have, reading room temperature from wherever you place the remote rather than from the hot air right next to the unit itself.
How to buy a casement window AC
- Confirm your window type first. If your window cranks outward or slides horizontally with no lower sash that raises, you’re in this category — a standard window AC (including this site’s usual top pick, the Midea U) has nothing to rest on or seal against.
- Size off the DOE-rated BTU, not the nameplate. As the Frigidaire FFRS1022R1 shows, the real number can be roughly half the advertised one. Look up the DOE figure on a big-box retailer’s spec tab before you buy.
- Measure both the width and the height. Casement units use tall, narrow adjustable panels — typically a 15–16 inch cabinet with panels extending up to about 3 feet — rather than the wide, short panels a standard window unit uses.
- Consider a portable AC instead. If a casement AC in your price range doesn’t cool enough real square footage, a portable air conditioner vents through a slim window kit that works in almost any window type, casement included, without needing a specialized cabinet at all.
The bottom line
For a casement, crank-out, or sliding window, the Frigidaire FFRS1022R1 is the best air conditioner of 2026 to actually find in stock — just size it off its 5,100 DOE-rated BTU, not the 10,000 on the box. Want quieter, more efficient running and don’t mind hunting for stock? The Koldfront CAC8000W is the better unit. And if none of these cool enough space for your room, a portable AC sidesteps the casement problem entirely.