How loud is the Keystone 18,000 BTU Window Air Conditioner - With Heat?

54 dB(A) indoors, about as loud as a dishwasher.

What size room does the Keystone 18,000 BTU Window Air Conditioner - With Heat cool?

It is rated to cool a room up to 1,000 sq ft (18,000 BTU · 5.3 kW).

Do I need a professional to install the Keystone 18,000 BTU Window Air Conditioner - With Heat?

No. It is a window unit you can fit yourself, no professional needed. Usually no permit.

Does the Keystone 18,000 BTU Window Air Conditioner - With Heat heat as well as cool?

Yes. It also heats, rated 16,000 BTU of heating output.

Window unit Heats too

Keystone · Model KSTHW18B

18,000 BTU Window Air Conditioner - With Heat

Name: Keystone 18,000 BTU Window Air Conditioner - With Heat
Brand: Keystone
Price: 849.99 USD
Availability: InStock

A window air conditioner rated at 18,000 BTU for rooms up to 1,000 sq ft. It heats in winter too and self-installs in a window.

$849.99

Buy at Sylvane In stock

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Will it cool your room?

Room size (assumed)861 sq ft ≈ 80 m²

Fits a 80 m² room

This unit's cooling matches a 861 sq ft room. Set your room size to check the fit for your space.

At a glance

Best for renters and rooms where you cannot install a fixed unit.

Cooling

5.3 kW

Size

Large

Noise

54 dB

Audible

Install: Self-fit, no pro neededPermission: Usually no permit

Performance

Cooling capacity: 18,000 BTU · 5.3 kW
Heating capacity: 16,000 BTU
Room coverage: up to 1,000 sq ft
Energy Star: Not published
CEER: Not published
Annual energy (cooling): Not published

Noise, size & features

Model number: KSTHW18B
Indoor noise: 54 dB(A)about as loud as a dishwasher
Outdoor noise: Not published
Indoor unit: 23.6 x 17.9 x 25.4 in
Outdoor unit: None
Refrigerant: R-32
Wi-Fi / app: Not published
Outdoor unit needed: No
Warranty: 1-Year Warranty

What is good

Heats as well as cools, which 31 of the 157 window units we list offer.
Uses R-32 (GWP 675), the low-GWP class new US residential equipment moved to.

What to watch

At $850 it costs more than 13 of the 17 other 15,000-18,000 BTU window units we list with a live price.

Installation & the rules that apply

This is a window unit. No EPA Section 608 technician is needed: the refrigerant circuit is factory-sealed and never opened. A plug-in window unit needs no permit, so the friction is with your building rather than the government. Many HOAs restrict window units on appearance grounds, though an HOA regulating how you mount one stands on much firmer ground than one banning cooling outright. Landlords can set conditions, and the falling hazard is taken seriously: New York City, for instance, requires window units to be supported by brackets or mounting rails, and many building insurers and HOAs now require a bracket regardless of city.

Installation

Self-fit, no pro needed

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 18,000 BTU Window Air Conditioner - With Heat

How loud is the Keystone 18,000 BTU Window Air Conditioner - With Heat?: 54 dB(A) indoors, about as loud as a dishwasher.
What size room does the Keystone 18,000 BTU Window Air Conditioner - With Heat cool?: It is rated to cool a room up to 1,000 sq ft (18,000 BTU · 5.3 kW).
Do I need a professional to install the Keystone 18,000 BTU Window Air Conditioner - With Heat?: No. It is a window unit you can fit yourself, no professional needed. Usually no permit.
Does the Keystone 18,000 BTU Window Air Conditioner - With Heat heat as well as cool?: Yes. It also heats, rated 16,000 BTU of heating output.