The units, honestly reviewed
Frigidaire FHSC082WB1
$589 MSRP — no longer sold by Frigidaire as of 2026-07-12
The category's reference unit — now discontinued. Frigidaire no longer sells either casement model (its site lists them as support-only pages, verified July 2026). The 8,000 BTU chassis is still what the category gets judged by: purpose-built, R-32 refrigerant, fill panels that make a tall opening look finished. If residual retailer stock surfaces at a clear discount, it can still be a fine buy.
- Type
- Casement/slider window AC
- Cooling Btu
- 8,000 BTU
- Coverage
- Up to 350 sq ft
- Window Fit
- 14.5 in min width × 20.25 in min height
- Speeds
- 3
- Refrigerant
- R-32
Where it earns its price
- Purpose-built for vertical openings — no plexiglass fabrication, no compromise seal
- 350 sq ft of real refrigerated cooling, which no 'ventless' workaround matches
- Frigidaire's support pages, manuals and parts listings are still up
Where it doesn't
- Discontinued — Frigidaire no longer sells it, so any remaining retailer stock is the end of the line
- At 60-plus pounds, installation is a two-person job
- If your opening is narrower than 14.5 inches, nothing in this category fits — go to the slide-kit path below
Skip it if: you want a unit with a future — the Keystone KSTSW08B below is the 8K casement unit still in production.
Sold out — no active buy link (restock TBC)
Frigidaire no longer sells this model direct — its page is support-only as of 2026-07-12 (user-spotted). Remaining dealer stock may exist; verify before buying.
Frigidaire FHSC102WB1
$639 MSRP — no longer sold by Frigidaire as of 2026-07-12
The same discontinued story at 10,000 BTU, for rooms up to 450 square feet. Frigidaire no longer sells it; if you find residual stock, buy it only if your room actually needs the extra capacity.
- Type
- Casement/slider window AC
- Cooling Btu
- 10,000 BTU
- Coverage
- Up to 450 sq ft
- Window Fit
- Same 14.5 in × 20.25 in chassis
- Speeds
- 3
- Weight
- 72 lb
Where it earns its price
- 450 sq ft of true refrigerated cooling in a vertical chassis
- Same 14.5-inch chassis — the extra BTU doesn't demand a wider window
- Three fan speeds with a 24-hour programmable timer
Where it doesn't
- Discontinued — no restock coming; remaining units sell at whatever retailers ask
- At 72 lb it's the heaviest lift here
- Oversized for bedrooms under ~350 sq ft — an 8K unit dehumidifies better in smaller rooms
Skip it if: your room is under 350 sq ft, or you can't find stock — the Keystone KSTSW10B is a 10K unit still being made.
Sold out — no active buy link (restock TBC)
Frigidaire no longer sells this model direct — its page is support-only as of 2026-07-12. Remaining dealer stock may exist; verify before buying. (24-hr timer; CFM 264/294/323.)
Keystone KSTSW08B
$464–500 (retailer-dependent) as of 2026-07-12
With Frigidaire out, this is the only 8,000 BTU casement unit still in production — no longer just the value pick. Same vertical form factor and 8K rating as the discontinued Frigidaire, with a dehumidifier mode and 4-way louvers, at a street price of $464–500 as of July 12 — up sharply from the $365–430 spread a week earlier, which is what a category with almost no makers left looks like.
- Type
- Casement/slider window AC
- Cooling Btu
- 8,000 BTU
- Coverage
- Up to 350 sq ft
- Speeds
- 3
- Extras
- Dehumidifier mode, 4-way louvers, remote
Where it earns its price
- The cheaper of the two Keystone casements still in production
- Dehumidifier mode is genuinely useful in shoulder seasons
- In production and widely stocked (Amazon, Home Depot, Walmart, Best Buy)
Where it doesn't
- Brand support network is thinner than Frigidaire's
- Prices are climbing now that Frigidaire is out ($365–430 on July 4, $464–500 on July 12) — shop around or you'll overpay
- We could not verify per-speed noise figures from the manufacturer
Skip it if: your room is over 350 sq ft — step up to the 10K KSTSW10B below instead.
Sold out — no active buy link (restock TBC)
Keystone's own page lists it at $463.99 (Amazon) and $479.99 (Home Depot, Walmart) against a $499.99 list, and Best Buy's price API confirmed $479.99 in-stock — all checked 2026-07-12. Prices moved up from the $365–430 spread we saw on 2026-07-04, so shop around.
Keystone KSTSW10B
$529.99 as of 2026-07-12
Keystone's 10,000 BTU version for bigger rooms — one of only two 10K casement units still being made (the other is Perfect Aire's 4PASC10000, $569 in stock at Sylvane as of 2026-07-12). Same honest math: buy capacity for the room you have, not the room you imagine.
- Type
- Casement/slider window AC
- Cooling Btu
- 10,000 BTU
- Coverage
- Up to 450 sq ft
- Speeds
- 3
- Extras
- 4-way louvers, remote
Where it earns its price
- The remaining path to 450 sq ft of casement cooling
- Same fit dimensions as its 8K sibling
- $529.99 list price at Keystone (as of 2026-07-12)
Where it doesn't
- Some retailers showed it on backorder in early July — confirm stock before scheduling an install
- Pricier per BTU than the 8K at street prices
Skip it if: you can't wait out a backorder — the Perfect Aire below is in stock, or the portable-AC-plus-slide-kit path works this week.
No direct buy link we earn on — search “Keystone KSTSW10B” at your usual retailer and confirm stock before you count on it.
No buy link here on purpose: Keystone sells only through retailers and we couldn't verify a direct product page that reliably works — search 'KSTSW10B' at your preferred retailer and check stock before planning an install date.
Perfect Aire 4PASC10000
$569.00 as of 2026-07-12
The other 10K casement unit still in production — and as of July 12 the one you can actually buy today: in stock at Sylvane at $569, server-verified 2026-07-12, while the Keystone 10K sat on backorder at several retailers. Follow Me remote thermostat (the remote doubles as the temperature sensor, so it cools to how the room feels where you sit), plus dry mode and an energy-saver cycle.
- Type
- Casement/slider window AC
- Cooling Btu
- 10,000 BTU
- Coverage
- Up to 450 sq ft
- Window Fit
- 15.5–16.25 in wide × 21.25–39.5 in tall
- Speeds
- 3
- Extras
- Follow Me remote thermostat, dry mode, energy saver, 24-hr timer
Where it earns its price
- In stock when we checked — the rest of the 10K casement field was backordered or discontinued
- Follow Me remote thermostat reads the temperature at your seat, not at the window
- Runs on a standard 125V/15A outlet — no special wiring
Where it doesn't
- Narrowest fit window on this page: the opening must be 15.5–16.25 inches wide — measure before ordering
- $569 is the priciest 10K path here as of July 12
- We could not verify manufacturer noise figures
Skip it if: your opening is narrower than 15.5 inches — the Keystone pair fits tighter openings, or take the slide-kit path below.
Sold out — no active buy link (restock TBC)
Amazon buy box live, server-verified 2026-07-22 (also listed at $569.00 at Sylvane on 2026-07-12). Fit is narrower than it looks: the opening must be 15.5–16.25 inches wide — measure before ordering. 125V/15A NEMA 5-15P plug (standard outlet).
Soleus Air WS4-08EW-301 (saddle)
$609.99 (sale) / $629.99 (reg.) as of 2026-07-12
A different idea entirely: the saddle unit drapes over the windowsill like a saddlebag, leaving most of the window usable and putting the weight on the wall rather than the glass. Clever, quiet in concept — and back in stock at Sylvane as of July 12 after a spotty season.
- Type
- Saddle window AC (straddles the sill)
- Cooling Btu
- 8,000 BTU
- Window Fit
- 24–48 in wide, 16 in min height, wall ≤12.5 in
- Extras
- Wi-Fi / voice control
Where it earns its price
- Window stays mostly usable, and no side-panel wall of plastic
- Fits a wide range of openings (24–48 inches) — works where casement units don't
- Wi-Fi and voice control, unusual in this category
Where it doesn't
- $609.99 even on sale — the priciest way to 8,000 BTU on this page
- Availability has been spotty all season — it was backordered as recently as early July
- Needs a wall under 12.5 inches thick and a 16-inch height clearance — measure the sill, not just the window
Skip it if: your wall is thicker than 12.5 inches, or you need a unit you can buy this week — the WS5-10HW-301 below is the same idea with a live buy box.
Sold out — no active buy link (restock TBC)
Back IN STOCK at Sylvane as of 2026-07-12 (live Add to cart, user-verified in a real browser; was backordered since early July). Sale price $609.99 against a $629.99 list — the earlier $689.99 list has come down.
Soleus Air WS5-10HW-301 (saddle, heat pump)
$699.99 as of 2026-07-22
The saddle idea, upsized and actually buyable: 10,000 BTU of cooling plus a 10,000 BTU heat pump, so one unit handles summer and the shoulder-season chill. Same over-the-sill design as the WS4 — it rests on the wall, leaves most of the glass clear, and can't fall out — but this is the model with a live buy box (Amazon, verified 2026-07-22) while the 8K WS4 and the Keystone casements sit on backorder or have no working cart.
- Type
- Saddle window AC with heat (straddles the sill)
- Cooling Btu
- 10,000 BTU
- Coverage
- Up to 450 sq ft
- Window Fit
- 24–48 in wide, wall/sill ≤12.5 in thick
- Extras
- 10,000 BTU heat pump, Wi-Fi / app, dehumidifier mode, MyTemp sensor, remote
Where it earns its price
- Buy box live when we checked — the one saddle unit here you can order today
- Heat pump: cools rooms up to ~450 sq ft in summer, warms them in spring and fall
- Sits over the sill, so the view stays mostly clear and no weight hangs on the glass
Where it doesn't
- $699.99 list at Sylvane (backordered there) — the priciest unit on this page; check the Amazon price before you buy
- Needs a wall/sill no thicker than 12.5 inches and a 24–48 inch window — measure the sill, not just the glass
- 10,000 BTU is oversized for a bedroom under ~350 sq ft, where it cools fast but dehumidifies worse
Skip it if: your room is under 350 sq ft — an oversized unit leaves it cold and clammy; size down or take the slide-kit path below.
Sold out — no active buy link (restock TBC)
Amazon buy box live, server-verified 2026-07-22 (Sylvane lists it at $699.99 but is backordered there — Amazon is the in-stock path). The saddle design sits on the windowsill so it never blocks your view and can't fall out; it's a heat pump, so it cools in summer and warms in the shoulder season. Needs a sill/wall no thicker than 12.5 inches and a window 24–48 inches wide — measure the sill, not just the window.
The path most pages bury: a portable AC plus a $40 panel
Casement units are excellent and expensive. The alternative: any decent single-hose portable AC vented through a TURBRO slide-kit panel ($39.99 as of 2026-07-12), which fits vertical and horizontal sliders from 11 to 61 inches. Total cost lands near the Keystone, but the AC rolls to another room in winter, and nothing permanent touches the window — which is why it's usually the renter's answer. The trade-offs are honest ones: a portable AC gives up some efficiency to a window unit, takes floor space, and the hose is a look. Our venting guide covers the details, including sliding-door panels for rooms with no usable window at all.
The panel for this path
TURBRO slide kit — $39.99
Sold out — no active buy link (restock TBC)
One caution while shopping this route: you will see the discontinued Koldfront CAC8000W/CAC10000W casement units at retailers — that's residual stock of a line the manufacturer ended, fine if the price is right but with no future parts support. We don't link them.
Questions people actually ask
Can you put a regular window air conditioner in a sliding window?
Sideways, no — a standard unit is engineered to drain and mount horizontally, and turning it on its side damages the compressor. In a horizontal slider a standard unit can sometimes work upright with a filler panel; in a vertical slider or casement window you need a purpose-built vertical unit or a portable AC with a slide-kit vent panel.
What is the difference between a casement AC and a saddle AC?
A casement (vertical) unit fills the window opening top to bottom, like a window unit rotated into a tall narrow box. A saddle unit hangs over the sill in a U-shape, resting on both sides of the wall, leaving most of the glass clear. Casement suits narrow tall openings; saddle needs a 24–48 inch opening and a wall under 12.5 inches thick.
How many BTU do I need for my room?
Roughly: 8,000 BTU for up to 350 sq ft, 10,000 BTU for up to 450 sq ft. Add capacity for uninsulated spaces, big sun-facing glass, or kitchens; subtract nothing for "just in case" — an oversized AC cools the air faster than it removes moisture and leaves the room cold but clammy.
Are Midea U-shaped air conditioners safe to buy in 2026?
The design is popular and quiet, but check the June 2025 CPSC recall first: about 1.7 million U/U+ units (also badged Frigidaire, Keystone, Danby, Insignia, Comfort Aire, Mr. Cool, Perfect Aire, Sea Breeze, LBG) were recalled for a mold risk, with a free repair or prorated refund as the remedy. We could not confirm whether new 2026 stock ships already fixed, so verify your unit's serial against the CPSC notice either way. Note U-shaped units are for double-hung windows — they don't solve the sliding-window problem this page covers.
Can I install a casement AC without drilling?
Mostly yes: the Frigidaire and Keystone units clamp and seal into the opening with included panels, though both manuals call for a support bracket or screws for security and most windows benefit from added weatherstripping. Renters should read the lease's alteration clause; the truly zero-drilling route is the portable-AC-plus-slide-kit path.