LG LT1237HNR Review: 11,200 BTU Wall AC with Supplemental Heat
LG's established heat and cool wall unit, rated 11,200 BTU for rooms up to 550 sq ft, with supplemental electric heat, a 230/208V NEMA 6-20 plug and a 55 dB listing.
By Daniel Brooks
Updated October 22, 2026
The LG LT1237HNR is one of the most established heat and cool wall units on the market. It is an 11,200 BTU through-the-wall air conditioner for rooms up to 550 square feet that adds supplemental electric heat for cooler days, so one unit covers summer cooling and spring and fall warmth. It runs on a 230/208 volt circuit with a NEMA 6-20 plug and has a 3.7 out of 5 average from 75 ratings, the most of any heat model in our through-the-wall air conditioners with heat category.
Parts of the product description refer to 11,800 BTU and 520 square feet. LG’s title, model name and specifications list 11,200 BTU and 550 square feet, and we use those figures here.
Our Verdict
The LT1237HNR is a dependable all-season wall unit for a bedroom, living room, apartment or office that already has a 230 volt sleeve outlet. It cools a medium room of about 25 by 22 feet, lists 55 dB, and covers the essentials with two cooling, heating and fan speeds, 4-way air deflection, a 24 hour timer, auto restart, a filter reminder and a remote. The thermostat runs from 60 to 86 degrees F in both modes.
Treat the heat as supplemental, which is how LG describes it. It takes the chill off a room on cool days, but it is not designed to replace central heat in a cold winter. The sleeve is sold separately, and there is no Wi-Fi.
LG LT1237HNR 11,200 BTU Through the Wall Air
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Key Specifications
| Feature | Specification |
|---|---|
| Brand | LG |
| Model | LT1237HNR |
| Type | Through-the-wall air conditioner with supplemental heat |
| Cooling Capacity | 11,200 BTU |
| Room Size | Up to 550 sq ft |
| Power | 230/208 volts, NEMA 6-20 LCDI plug |
| Max Wattage (listed) | 3500 watts |
| Efficiency | 9.7 (listed) |
| Noise Level | 55 dB (listed) |
| Thermostat Range | 60 to 86 degrees F |
| Fan Speeds | 2 cooling, heating and fan speeds |
| Dimensions | 24 x 14.41 x 20.09 inches (W x H x D) |
| Weight | 82 pounds |
| Wall Sleeve | Sold separately |
| Warranty | 1 year parts and labor |
Cooling Capacity and Room Size
LG rates the LT1237HNR for rooms up to 550 square feet and describes it as ideal for medium rooms of 25 by 22 feet. In the ENERGY STAR chart below, 11,200 BTU sits between the 10,000 and 12,000 BTU rows, so it is a realistic match for a medium living room, a large bedroom, an office or the main room of an apartment.
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.
Supplemental Heat
The heat mode is the reason to choose this unit over LG’s cooling-only wall models. On cooler days, the electric heater adds warmth to the room using the same fan and louvers as the air conditioner, and the same 60 to 86 degree F thermostat range applies. That is ideal for spring and fall mornings, a chilly home office, or a room that the central heating system does not reach well.
Electric resistance heat is simple and reliable, but it is not cheap to run for hours on end. LG lists a maximum of 3500 watts for this unit, which reflects the extra load of the heating element. Use it to supplement a main heating system rather than as the only heat source in a cold climate. In mild climates, or in a well-insulated apartment, it can comfortably handle many cool evenings on its own.
Power Requirements
The LT1237HNR requires a special 230/208 volt LCDI plug of the NEMA 6-20 type. That receptacle is common in apartment buildings with wall units, but it is different from a standard household outlet. Check the outlet beside your sleeve before ordering, and do not try to adapt the plug.
Installation and Sleeve Fit
The chassis measures 24 inches wide, 14.41 inches tall and 20.09 inches deep, the same 24 inch width as LG’s cooling-only wall units, so it fits the same family of sleeves. The sleeve is sold separately. In the box you get a remote, a mesh filter, a trim kit and the manual. At 82 pounds, this is a two-person installation.
Noise and Efficiency
LG lists 55 dB, which is reasonable for a unit of this size and lower than several rivals with heat. It is comfortable in a living room and workable in a bedroom. The listed efficiency figure of 9.7 is typical for a conventional heat and cool wall unit. An energy saving option and the 24 hour timer help keep running costs down in both seasons.
Controls and Everyday Use
The digital control panel and remote handle two cooling, heating and fan speeds, the timer and the mode switch. Four-way air deflection directs air up, down, left or right, which is especially useful in heat mode, because warm air tends to stay near the ceiling unless you aim it downward. Auto restart returns the unit to its previous settings after a power outage, and the filter light reminds you to rinse the washable filter.
Who It Suits Best
The LT1237HNR suits medium rooms up to 550 square feet with a 230/208 volt sleeve outlet, in homes that want cooling in summer and extra warmth on cool days. It is a natural replacement for older LG heat and cool wall units. It is less suited to homes with only standard outlets, smart home users, or anyone who needs a primary heat source for a cold winter.
Pros and Cons
| Pros | Cons |
|---|---|
| Cooling and supplemental heat in one unit | Needs a NEMA 6-20 outlet |
| 75 ratings, a long track record | Heat is supplemental only |
| 55 dB listed sound level | Only 2 fan speeds |
| Fits LG’s 24 inch chassis sleeves | Sleeve sold separately |
| Auto restart and 24 hour timer | No Wi-Fi |
Who Should Buy It
| Who Should Buy It? | Who Should Look Elsewhere? |
|---|---|
| Apartments with a 230V sleeve outlet | Homes with only standard outlets |
| Rooms that run cool in spring and fall | Cold climates needing primary heat |
| Replacements for older LG heat units | Smart home users |
| Medium rooms up to 550 sq ft | Small bedrooms |
For more choices, see our picks for the best through-the-wall air conditioners with heat and the best 230V through-the-wall air conditioners with heat.
Final Verdict
The LG LT1237HNR is a proven, relatively quiet heat and cool wall unit for rooms up to 550 square feet. If you have a NEMA 6-20 outlet and want one appliance for summer cooling and shoulder-season warmth, it is an easy recommendation. You can check the current price and details for the LG LT1237HNR 11,200 BTU Through the Wall Air Conditioner with Heat.
Frequently Asked Questions
Does the LG LT1237HNR heat a room?
Yes. It has a supplemental heat option for cooler days, with the same 60 to 86 degree F thermostat range.
What plug does it need?
It requires a 230/208V LCDI plug of the NEMA 6-20 type.
What size room does it cool?
LG rates it for rooms up to 550 square feet.
Is the wall sleeve included?
No. The sleeve is sold separately.
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.