A through-the-wall (TTW) air conditioner installs in a permanent metal sleeve cut into an exterior wall, delivering the same cooling as a window AC without occupying a window. The best TTW unit in 2026 is the Friedrich WCT12A30A (12,000 BTU, EER 11.3, 44 dB), priced at approximately $680 plus $80 for the wall sleeve.
Through-the-wall units are ideal for rooms without suitable windows, buildings where window ACs are prohibited, and permanent installations where seasonal removal isn't desired. Total installation cost typically ranges from $650–$1,500 including the unit, sleeve, and professional labor.
How Through-the-Wall ACs Differ from Window ACs
The internal refrigeration system is identical — both use vapor-compression with an evaporator, condenser, and compressor. The key differences are mounting and airflow:
| Feature | Window AC | Through-the-Wall AC |
|---|---|---|
| Installation location | Window opening | Dedicated wall opening |
| Mounting | Sits on windowsill, sash holds in place | Slides into permanent metal sleeve |
| Rear airflow direction | Straight back (outdoor) | Straight back through wall |
| Side ventilation | Some models vent from sides | Never — sides sealed by wall sleeve |
| Seasonal removal | Easy (20 minutes) | Not typically removed |
| Interchangeability | Any brand in any window | Must match sleeve dimensions |
A window AC and a through-the-wall AC are NOT interchangeable. Window ACs vent from the sides and back; TTW units vent only from the rear because the wall sleeve blocks side airflow. Installing a window AC in a wall sleeve restricts airflow and can cause compressor overheating and failure. Always buy a unit specifically rated for through-the-wall installation.
Top Through-the-Wall ACs Ranked
| Rank | Model | BTU | EER/CEER | Noise | Heat? | Sleeve Size | Price (Unit) | Price (Sleeve) |
|---|---|---|---|---|---|---|---|---|
| 1 | Friedrich WCT12A30A | 12,000 | 11.3 EER | 44 dB | No | 26"×16.5" | $680 | $80 |
| 2 | Friedrich WET12A33A | 12,000 | 10.5 EER | 45 dB | Yes (3,500 BTU) | 26"×16.5" | $780 | $80 |
| 3 | LG LT1237HNR | 12,000 | 10.2 EER | 46 dB | Yes (11,200 BTU) | 26"×17" | $720 | $90 |
| 4 | Friedrich WCT10A10A | 10,000 | 11.0 EER | 43 dB | No | 26"×16.5" | $580 | $80 |
| 5 | Frigidaire FHTE123WA2 | 12,000 | 10.4 EER | 47 dB | Yes (10,600 BTU) | 26.5"×16.5" | $620 | $75 |
| 6 | Keystone KSTAT10B | 10,000 | 10.5 EER | 48 dB | No | 26"×16.5" | $480 | $70 |
| 7 | GE AJCQ12DCH | 12,000 | 10.0 EER | 48 dB | No | 26.5"×16.5" | $550 | $85 |
Wall Sleeve Specifications
The wall sleeve is a metal chassis permanently mounted in the wall opening. The AC unit slides into it like a drawer.
Standard Sleeve Dimensions
| Sleeve Type | Width | Height | Depth Range | Fits Wall Thickness |
|---|---|---|---|---|
| Standard residential | 26"–27" | 16"–17.5" | 16"–20" | 4"–16" |
| PTAC-style (commercial) | 42" | 16" | 16"–20" | 4"–16" |
| Compact residential | 24" | 15" | 14"–18" | 4"–12" |
Most residential TTW ACs use a 26"×16.5" sleeve. Always buy the sleeve specified by the AC manufacturer to ensure proper fit, airflow, and weathersealing.
Installation Requirements
| Requirement | Detail | Cost |
|---|---|---|
| Wall opening | Rectangular hole through exterior wall, sized to sleeve | Included in labor |
| Structural assessment | Verify no load-bearing elements will be cut | $0–$200 (separate inspection) |
| Framing | Wood header and jack studs around opening | Included in labor |
| Insulation | Seal around sleeve perimeter | $10–$30 materials |
| Exterior weatherproofing | Flashing, caulk, trim | $20–$50 materials |
| Electrical | Dedicated outlet near installation | $150–$300 if not existing |
| Total professional installation | Cut, frame, sleeve, seal, electrical | $200–$600 labor |
Example 1: Hotel Renovation — The Bayshore Inn replaced 48 aging PTAC units with Friedrich WET12A33A through-the-wall models. Each unit slides into the existing wall sleeve, providing both cooling and heating. Room-by-room temperature control with no ductwork. Installation per room: 2 hours, $180 labor.
Example 2: Brownstone Without Window Access — The Lees' Brooklyn brownstone had ornamental windows that couldn't accommodate a window AC. They installed a Friedrich WCT12A30A through a side wall for $1,350 total (unit + sleeve + professional installation). The unit cools their 500 sq ft living area without touching any windows.
Example 3: Condo with HOA Window Restrictions — Maria's condo HOA bans window-mounted ACs for aesthetic reasons. She installed an LG through-the-wall unit ($720 + $90 sleeve + $400 installation = $1,210 total). The wall-mounted unit sits flush against the exterior and doesn't violate the HOA's rules. Heat pump mode provides supplemental winter heating.
TTW vs. Window AC: Cost Comparison
| Factor | Window AC | Through-the-Wall AC |
|---|---|---|
| Unit cost (12K BTU) | $400–$520 | $580–$780 |
| Sleeve/mounting | $0 (uses window) | $70–$100 |
| Installation labor | $0 (DIY) | $200–$600 |
| Total upfront | $400–$520 | $850–$1,480 |
| Efficiency (12K BTU) | CEER 11.5–15.15 | EER 10.0–11.3 |
| Annual electricity | $64–$84 | $86–$97 |
| Seasonal removal | Required in cold climates | Not needed |
Through-the-wall units cost 2–3x more upfront and are slightly less efficient than the best window ACs. Their value proposition is: permanent installation, no window blockage, and suitability for rooms without compatible windows.
Key Takeaways
- TTW units are functionally identical to window ACs but mount in a wall sleeve instead of a window.
- Friedrich dominates the TTW market with the widest selection and best build quality.
- Never install a window AC in a wall sleeve — side airflow blockage causes overheating and compressor failure.
- Total installation costs $650–$1,500 (unit + sleeve + labor). Budget $200–$600 for professional wall cutting and framing.
- TTW units with heat (Friedrich WET, LG HNR, Frigidaire FHTE) provide year-round climate control in a single unit.
- Best for: rooms without windows, HOA-restricted buildings, permanent installations, and hotel/commercial use.