Do I need a professional to install the Keystone 12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat?

Not to replace a unit, but usually yes for a new opening. Sliding it into an existing wall sleeve it fits is a job you can do yourself (it is heavy, so plan on two people), with no refrigerant work. A new installation means cutting an opening through an exterior wall and fitting a sleeve, which is contractor work and usually needs a building permit. It runs on 230 volts, so it needs a matching 230-volt outlet on its own circuit, and adding one is a job for an electrician.

Through-the-wall unit Heats too

Keystone · Model KSTAT12-2HD

12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat

Name: Keystone 12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat
Brand: Keystone
Price: 649.99 USD
Availability: InStock

A through-the-wall air conditioner rated at 12,000 BTU for rooms up to 550 sq ft. It heats in winter too and installs in a wall sleeve.

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Will it cool your room?

Room size (assumed)550 sq ft ≈ 51.1 m²

Fits a 51.1 m² room

This unit's cooling matches a 550 sq ft room. Set your room size to check the fit for your space.

At a glance

Best for replacing a through-the-wall unit in an existing wall sleeve.

Cooling

3.5 kW

Size

Average

Noise

56.5 dB

Audible

Install: Slides into a wall sleevePermission: A new wall opening usually needs a permit

Performance

Cooling capacity: 12,000 BTU · 3.5 kW
Heating capacity: 10,600 BTU
Room coverage: up to 550 sq ft
Energy Star: Not published
CEER: Not published
Annual energy (cooling): Not published

Noise, size & features

Model number: KSTAT12-2HD
Indoor noise: 56.5 dB(A)about as loud as a dishwasher
Outdoor noise: Not published
Indoor unit: 24.2 x 14.5 x 20.3 in
Outdoor unit: None
Refrigerant: R-32
Wi-Fi / app: Not published
Outdoor unit needed: No
Wall sleeve: Fits 25½ to 27 in. sleeves
Warranty: 5-Year Limited Warranty

Will it fit your wall sleeve?

Keystone's installation manual lists the existing sleeves it fits, from Frigidaire, GE/Hotpoint, Whirlpool, Fedders/Emerson, Sears/Kenmore, Carrier and Friedrich (25½ to 27 inches wide), and the old rear grille is replaced by the one in the kit. Keystone's own sleeve for a new installation is the KSTSLV1, sold as a 26-inch sleeve (its spec sheet gives 25½ x 15¼ x 17½ in.), for walls up to 17¾ inches thick. Source: Keystone installation manual

Every through-the-wall AC and PTAC by the sleeve it fits

Installation & the rules that apply

This is a through-the-wall air conditioner. It sits in a sleeve built into an exterior wall, so the window-unit mounting and bracket rules do not apply to it. Swapping it into an existing sleeve is a like-for-like replacement; cutting a new opening changes the building's exterior wall, which usually needs a building permit and, in a condo, co-op or historic building, approval first.

Installation

Slides into a wall sleeve

Refrigerant

R-32

GeneralRenters: get written landlord consent firstReviewed June 2026Often blocks install

GeneralCondo / HOA: exterior changes need approvalReviewed June 2026Permit required

GeneralHistoric / listed buildings: consent before any exterior unitReviewed June 2026Permit required

MassachusettsMassachusetts: local historic district approval (MGL c.40C)Reviewed June 2026Permit required

United StatesUS: local mechanical and electrical permits (vary by city)Reviewed June 2026Permit required

See full rules by region

Common questions about the Keystone 12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat

How loud is the Keystone 12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat?: 56.5 dB(A) indoors, about as loud as a dishwasher.
What size room does the Keystone 12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat cool?: It is rated to cool a room up to 550 sq ft (12,000 BTU · 3.5 kW).
Do I need a professional to install the Keystone 12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat?: Not to replace a unit, but usually yes for a new opening. Sliding it into an existing wall sleeve it fits is a job you can do yourself (it is heavy, so plan on two people), with no refrigerant work. A new installation means cutting an opening through an exterior wall and fitting a sleeve, which is contractor work and usually needs a building permit. It runs on 230 volts, so it needs a matching 230-volt outlet on its own circuit, and adding one is a job for an electrician.
Does the Keystone 12,000 BTU Through-The Wall 230V Air Conditioner - Cool/Heat heat as well as cool?: Yes. It also heats, rated 10,600 BTU of heating output.