LG LW1823HRSM 18,000 BTU Window AC with Heat Review: ThinQ
An 18,000 BTU 230V window air conditioner with supplemental heat for rooms up to 1,000 sq. ft., with LG ThinQ app control, Alexa and Hey Google support, a remote, 24-hour timer and 4-way air deflection.
By Daniel Brooks
Updated October 8, 2026
The LG LW1823HRSM 18,000 BTU Window Air Conditioner with Heat is a 230V cooling and supplemental heating unit for medium and large rooms up to 1,000 square feet. LG gives an example room of 40 by 25 feet. It adds LG ThinQ Wi-Fi control and works with Alexa and Hey Google. Among large conventional window air conditioners, it is one of the few smart units with heat, with 3.6 stars from 32 ratings.
It also includes a remote, a 24-hour timer, 4-way air deflection and auto restart. The main points to check are the 230V outlet requirement and the 132 pound weight. We evaluated it based on the manufacturer’s specifications.
Our Verdict
This LG is a strong pick for a large living room, open-plan space or apartment that needs serious cooling and some warmth on cooler days. Its strongest points are the 1,000 square foot coverage, supplemental heat, ThinQ app control with Alexa and Hey Google, the remote, the 24-hour programmable timer, 4-way air deflection, auto restart, Energy Saver mode and a check filter alert.
The trade-offs are significant for some homes. It needs a 230V outlet, weighs 132 pounds and has only 2 cooling, heating and fan speeds. The listed noise level is 61 dB, and there is no inverter. If your room is large and you already have, or can add, a 230V outlet, it is worth considering.
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Key Specifications
| Feature | Specification |
|---|---|
| Brand | LG |
| Model | LW1823HRSM |
| Type | Window air conditioner with heat |
| Cooling Capacity | 18,000 BTU |
| Heating | Supplemental heat |
| Room Size (listed) | Up to 1,000 sq. ft. |
| Efficiency | 11.1 (listed as SEER) |
| Noise Level | 61 dB |
| Voltage / Power | 230V, 3670W |
| Window Fit | 29″ to 41″ wide, 18″ minimum height |
| Dimensions | 30.5″D x 25.5″W x 16.83″H |
| Weight | 132 pounds |
| Speeds | 2 cooling, heating and fan speeds |
| Controls | Electronic panel, remote, ThinQ app, Alexa, Hey Google |
| Airflow | 4-way air deflection |
| Filter | Removable, washable, check filter alert |
| Compressor | No inverter |
| Refrigerant | R-32 |
| Warranty | 1 year limited |
Cooling Capacity and Room Size
LG rates the LW1823HRSM at 18,000 BTU for rooms up to 1,000 square feet, using a 40 by 25 foot room as its example. That covers a large living room, an open kitchen and dining area or a small apartment.
The 4-way air deflection lets you direct airflow where it is needed most, whether you are cooling, heating or circulating air. In a long room, aim the airflow toward the far end so the area farthest from the window does not stay warm.
With only 2 cooling speeds, there is less fine control than on some units. Use the timer and Energy Saver mode to manage comfort and running time.
ENERGY STAR publishes this general guide for sizing a room air conditioner by floor area:
| Room Size (sq ft) | Cooling Capacity (BTU/hr) |
|---|---|
| 100 to 150 | 5,000 |
| 150 to 250 | 6,000 |
| 250 to 300 | 7,000 |
| 300 to 350 | 8,000 |
| 350 to 400 | 9,000 |
| 400 to 450 | 10,000 |
| 450 to 550 | 12,000 |
| 550 to 700 | 14,000 |
| 700 to 1,000 | 18,000 |
Adjust for your room: reduce capacity by 10 percent for a heavily shaded room, increase it by 10 percent for a very sunny room, add 600 BTU for each regular occupant beyond two, and add 4,000 BTU if the unit cools a kitchen. Source: ENERGY STAR.
At its listed 18,000 BTU, it lines up with rooms of about 700 to 1,000 square feet, which matches LG’s coverage claim. In a room well under 700 square feet, a smaller unit is usually a better fit.
Heating Performance
LG describes the heat as supplemental, meant to add warmth on cooler days rather than replace a full heating system. It works best in spring and autumn or in a room that a central system does not heat well.
Heat mode is controlled the same way as cooling, from the panel, remote, app or voice. The 24-hour timer lets you warm the room before you get home or before you wake up.
Installation and Fit
The window opening must be 29 to 41 inches wide with a minimum height of 18 inches. A window installation kit and window curtain panels are included.
The cabinet measures 30.5 inches deep, 25.5 inches wide and 16.83 inches tall, and weighs 132 pounds. That is a two-person job at the very least, and the window, sill and support bracket must be able to carry the load. Many buyers will want professional installation.
It runs on 230V power. A standard household outlet will not work, so check that you have the right outlet near the window before buying. The listed wattage is 3670 watts. Check the manual for the circuit and plug requirements.
Noise, Energy Use and Efficiency
The listed noise level is 61 dB, which is on the louder side. That is typical for a unit of this capacity, and it suits a living area more than a bedroom.
The listing gives an efficiency figure of 11.1, labeled as SEER. Energy Saver mode is LG’s main tool for reducing energy use. There is no inverter compressor, so the unit cycles on and off to hold the set temperature.
Controls and Smart Features
LG ThinQ lets you start or stop cooling, change the mode or set the temperature from your phone while you are away. Alexa and Hey Google support lets you change settings with simple voice commands.
The electronic controls and included remote cover day-to-day use from across the room. The 24-hour programmable timer lets you build a schedule, so the room can be cool or warm when you get home.
Auto restart turns the unit back on automatically when power is restored after an outage. For a large room that is used every day, that keeps comfort steady without a manual reset.
Maintenance and Drainage
The filter is removable and washable, and a check filter alert reminds you when it is time to clean it. Slide it out, rinse it, let it dry fully and slide it back in. A clean filter keeps airflow steady, which matters in a large room.
The listing does not describe condensate drainage. Check the manual for how water is handled and for the steps to store the unit at the end of the season.
Pros and Cons
| Pros | Cons |
|---|---|
| Cools rooms up to 1,000 sq. ft. | Needs a 230V outlet |
| Supplemental heat for cooler days | Very heavy at 132 pounds |
| ThinQ app, Alexa and Hey Google | Only 2 cooling, heating and fan speeds |
| Remote and 24-hour timer | Listed noise level of 61 dB |
| Auto restart and check filter alert | No inverter compressor |
Who Should Buy It
| Who Should Buy It? | Who Should Look Elsewhere? |
|---|---|
| Rooms of about 700 to 1,000 sq. ft. | Homes without a 230V outlet |
| Homes that want cooling and some heat | Rooms well under 700 sq. ft. |
| Smart home users with Alexa or Google | Bedrooms and light sleepers |
| Buyers who want a schedule and remote | Anyone wanting a DIY one-person install |
| Large windows 29″ to 41″ wide | Buyers set on an inverter compressor |
Final Verdict
The LG LW1823HRSM 18,000 BTU Window Air Conditioner with Heat combines coverage for rooms up to 1,000 square feet with supplemental heat, ThinQ app and voice control, a remote, a 24-hour timer, 4-way air deflection and auto restart. The compromises are a 230V outlet requirement, a 132 pound cabinet and a listed 61 dB. You can check the current price and details for the LG LW1823HRSM 18,000 BTU Window Air Conditioner with Heat, or compare other 18,000 BTU window air conditioners.
Frequently Asked Questions
What size room is the LG LW1823HRSM for?
LG rates it for rooms up to 1,000 square feet. On the ENERGY STAR chart, 18,000 BTU fits rooms of about 700 to 1,000 square feet.
Does it need a special outlet?
Yes. It runs on 230V power, so it needs a higher-voltage outlet rather than a standard household one.
Can I control it with my phone?
Yes. LG ThinQ lets you control it from your phone, and it works with Alexa and Hey Google.
What window size does it fit?
The opening must be 29 to 41 inches wide with a minimum height of 18 inches.
About the author
Daniel Brooks is a home cooling editor at WikiCooling, covering window, portable, through-the-wall and mini-split air conditioners, fans, and dehumidifiers. He researches cooling capacity, energy efficiency, noise levels, installation requirements, and buyer feedback to help homeowners choose the right unit for their room size, climate, and budget.