Home / Comparisons / 18,000 BTU wall-mounted heat pumps
GREE EXTRÊME R32 and LG ARTCOOL PRESTIGE R32, 18,000 BTU on the label
Two R-32 wall units sold as 18,000 BTU, ENERGY STAR cold-climate certified and offered by AirGreen. The figure on the label is their cooling capacity. In heating, NEEP certifies a maximum capacity well above 18,000 BTU/h for each in mild weather, then less and less as the cold deepens. This page shows how much each one keeps, at what temperature, and what the certificates do not let you compare.
GREEEXTRÊME R32 18,000 BTU
GWH18AVEXF-D6DNA1B/I / GWH18AVEXF-D6DNA1B/O · AHRI 215386340
Same model numbers as the 18,000 BTU GREE AIRY R32 (AIRY brochure); NEEP files this certificate under the “Airy” series.
View the product page
LGARTCOOL PRESTIGE R32 18,000 BTU
KNSAL181A / KUSAL181A · AHRI 215828275
Sold in the United States as the Art Cool Premier (LG KSSAL181A submittal sheet). No other known name for this certificate in AirGreen’s lineup.
View the product pageWhat the electricity costs, in dollars, winter and summer
AirGreen estimate for the same 18,000 BTU/h zone in Montréal, on Hydro-Québec Rate D, taxes included. Both heat pumps are calculated exactly the same way, with the same method as on all our comparison pages; only their certified efficiencies change. Electric baseboards serve as the reference point.
How this amount is calculated
- Heat needed over the winter. A zone whose heat loss reaches 18,000 BTU/h ( kW) at −23.1 °C, Montréal’s design temperature: kW × 24 h × 4,167 degree-days ÷ (18 − (−23.1)) = kWh of heat for round-the-clock heating, all winter. Heating degree-days (base 18 °C) and design temperature: Natural Resources Canada, HOT2000 climate data, Montréal Intl station. With fewer hours a day (“Heating” slider), the heat is reduced in the same proportion, for the heat pump as for the baseboards: a simplification that does not account for recovery after a temperature setback.
- Electricity for heating. Heat pump: heat × 3.412 ÷ Region V HSPF2, the AHRI certificate value published by NEEP. Region V is the coldest in the standard, and its calculation includes the electric backup expected when the heat pump is no longer enough. Electric baseboards: 1 kWh of electricity for 1 kWh of heat.
- Electricity for cooling. 18,000 BTU/h ÷ SEER2 × hours a day × 60 days ÷ 1,000: the method of Hydro-Québec’s air-conditioning calculator, with the seasonal SEER2 efficiency from the AHRI certificate. The number of hours is a scenario, adjustable above from 1 to 24 h. At 24 h, the calculation assumes rated capacity all day long: that is a maximum, since a variable-speed unit slows down once the room is at the right temperature.
- Price. Hydro-Québec Rate D in effect April 1, 2026: 7.065¢ per kWh up to 40 kWh a day, 11.142¢ beyond; the average price, 9.104¢, is the one Hydro-Québec’s calculators use. GST and QST included. Network access charges, the same with or without a heat pump, are not counted.
AirGreen method v1.1, November 9, 2026. An estimate is for comparing units under the same conditions. The actual bill depends on the house, insulation, settings and use; this amount is not a promise.
18,000 BTU on the label: how much heat, at what temperature
The dotted line marks 18,000 BTU/h, the rated cooling capacity of both units. Each bar is a published maximum heating capacity, at its exact temperature; the pale part is what exceeds the label. The two manufacturers do not have their coldest point certified at the same temperature: where only one figure exists, the other unit shows the two published values on either side, or the limit of its stated range.
NEEP-certified values (records 389441 and 385473), accessed November 9, 2026. −18 °C: LG ARTCOOL PRESTIGE R32 brochure (2025), not certified. Percentages calculated by AirGreen on 18,000 BTU/h; LG also expresses its capacities as percentages, but of its rated heating capacity of 21,600 BTU/h (100% at −15 °C, 68% at −25 °C).
Same label, two different footprints outdoors
The two outdoor units are almost the same width. LG’s is 6.2 in taller, 40.6 lb heavier, and its circuit holds more refrigerant. These are manufacturer data; they describe the unit, not its performance, which is in the certificates above.
Outdoor unit weight
To plan for the wall bracket or the ground base.
R-32 factory charge
Both are precharged for 24.6 ft of piping; beyond that, GREE specifies 0.4 oz/ft and LG 0.32 oz/ft.
Pipe diameter
The gas line is the same; LG’s liquid line is one size larger. The installer follows the published diameter for each unit.
The coldest point of each
Five degrees separate the two tests. NEEP does not publish the EXTRÊME R32 at −25 °C or the ARTCOOL PRESTIGE at −30 °C, and LG states a heating range that stops at −25 °C: these two figures describe each unit, they do not compare with each other.
Below −15 °C: every published figure, at its exact temperature
NEEP certifies both units at −15 °C, then each at its own cold point: −30 °C for the EXTRÊME R32, −25 °C for the ARTCOOL PRESTIGE. LG adds a capacity at −18 °C in its brochure. Between two figures, the table shows the two published values on either side of the temperature.
What each manufacturer writes, line by line
GREE Canada EXTRÊME R32 brochure (document 032025) and GREE AIRY R32 brochure, which carries the same model numbers; LG ARTCOOL PRESTIGE R32 brochure (2025) and LG KSSAL181A submittal sheet. Base pan heater: data each manufacturer declared to NEEP.
EXTRÊME R32: heating stated down to −30 °C; 96 W base pan heater, runs below 1 °C outdoors or during defrost.
ARTCOOL PRESTIGE R32: LGRED heating technology; heating stated down to −25 °C; 90 W base pan heater, runs at 0 °C and below, in heating mode.
EXTRÊME R32: down to −29 °C outdoors.
ARTCOOL PRESTIGE R32: down to 14 °F (−10 °C) outdoors; down to 0 °F (−18 °C) with the optional ZLABGP04B wind baffle.
EXTRÊME R32: “G-AI Learning”; vertical and horizontal louver swing; sleep and timer functions (AIRY brochure).
ARTCOOL PRESTIGE R32: Jet Cool and Jet Heat, sleep mode, 24-hour timer, 4-way auto swing, automatic changeover between heating and cooling.
EXTRÊME R32: Built-in Wi-Fi (app not named); wireless remote.
ARTCOOL PRESTIGE R32: Built-in Wi-Fi, LG ThinQ app, Smart Diagnosis; wireless remote; wired controllers, remote sensor and gateways optional.
EXTRÊME R32: “low-voltage start-up” and automatic voltage adaptation (AIRY brochure).
ARTCOOL PRESTIGE R32: automatic restart after a power outage (submittal sheet).
EXTRÊME R32: washable filters, auto-clean; “G10 Inverter”, two-stage variable-speed compressor; anti-corrosion coated fins.
ARTCOOL PRESTIGE R32: self-cleaning indoor coil; GoldFin fins; twin rotary variable-speed compressor.
A2L refrigerant leak sensor included: stated in the GREE AIRY R32 brochure (same model numbers); the LG documents consulted do not mention one.
How loud each one is, per its manufacturer
GREE publishes seven levels for the 18,000 BTU EXTRÊME R32, with no speed names. LG publishes four cooling speeds for the ARTCOOL PRESTIGE, from the slowest (“very low”) to “high”. Both give a sound pressure in dB(A).
How to read these figures. dB(A) measures a noise level as the ear perceives it: the lower the figure, the quieter the unit. Each point is a fan speed published by the manufacturer, from the slowest to the fastest.
Why this is not a ranking. LG measures in an anechoic chamber to ISO 3745, without publishing the distance. GREE publishes neither the distance nor the measurement conditions in its brochure. A difference of a few dB(A) can come from the method as much as from the unit.
Indoor unit, in the room
Cooling, every published speed
Outdoor unit, outside
Highest published speed
Measurements taken by each manufacturer with its own method: read them separately, not as a ranking.
Sources: GREE Canada EXTRÊME R32 brochure (document 032025), 18,000 BTU column; LG ARTCOOL PRESTIGE R32 brochure (2025) and KSSAL181A submittal sheet, which specifies ISO 3745 and a tolerance of ±1 dB(A).
On the wall, in the piping, outdoors
Is your wall wide enough?
Unit width only, to scale. The side clearances required by the installation manual come on top; the installer confirms them on site.
Piping length
Colored band: precharged length. Dark mark: published maximum. Additions per the manufacturer: 0.4 oz/ft (GREE, AIRY 18,000 BTU brochure) and 0.32 oz/ft (LG).
Indoor units to scale
Width × height × depth per the manufacturers. The EXTRÊME R32 is 1.98 in wider; the ARTCOOL PRESTIGE is taller (14 3/16 vs 13 21/32 in).
| Installation | EXTRÊME R32 | ARTCOOL PRESTIGE R32 |
|---|---|---|
| Maximum piping length | 131.2 ft | 164.0 ftMinimum 9.8 ft. |
| Precharged length | 24.6 ftGREE AIRY R32 brochure, 18,000 BTU column; add 0.4 oz/ft beyond that. The EXTRÊME brochure does not give it. | 24.6 ftAdd 0.32 oz/ft beyond that. |
| Maximum height difference | 82 ft | 98.4 ft |
| Liquid – gas line diameters | 1/4 – 5/8 in | 3/8 – 5/8 in, flare fittings |
| Outdoor unit W × H × D, weight | 37 23/32 × 25 63/64 × 15 53/64 in, 94.8 lb | 37 13/32 × 32 3/16 in (L × H), 135.4 lbThe brochure prints a depth of 10 7/16 in, the same value as the indoor unit: to be confirmed at quote time. |
| Indoor unit, weight | 38.6 lb | 37.7 lb |
| Electrical protectionPer the manufacturer | MOP 25 A (MCA 20 A) | MOP 30 A (MCA 19 A) |
| Dehumidification | 1.8 L/h | 2.0 L/hPrinted as 4.23 pints/h. |
| Outdoor unit base pan heaterDeclared by the manufacturer to NEEP | Yes, 96 WRuns below 1 °C outdoors or during defrost. | Yes, 90 WRuns at 0 °C and below, stops at 1 °C, in heating mode. |
| Refrigerant and factory charge | R-32, 47.6 oz | R-32, 65.3 oz |
| Stated heating / cooling range | −30 to 30 °C / −29 to 50 °C | −25 to 18 °C / −10 to 48 °CHeating in wet bulb, per the LG brochure. |
What people ask about these two 18,000 BTU wall units
Which one heats more at −15 °C?
NEEP certifies 21,600 BTU/h at maximum for the ARTCOOL PRESTIGE and 18,000 BTU/h for the EXTRÊME R32 at −15 °C. At −8.3 °C: 24,300 and 20,100 BTU/h. These are temperatures where both are measured under the same conditions.
And in extreme cold, at −25 or −30 °C?
The two coldest points are not at the same temperature: 14,780 BTU/h at −25 °C for the ARTCOOL PRESTIGE, 10,800 BTU/h at −30 °C for the EXTRÊME R32. NEEP does not publish the other unit at those temperatures, and LG states a heating range that stops at −25 °C. These figures do not compare directly.
What does “18,000 BTU” on the label mean?
It is the certified rated cooling capacity, at 35 °C outdoors, the same for both. In heating, each unit has its own certified capacity at each temperature: from 23,000 to 10,800 BTU/h at most for the EXTRÊME R32, from 27,400 to 14,780 BTU/h for the ARTCOOL PRESTIGE, depending on the point.
Which one costs less to run?
The estimate at the top of the page applies the same method to both. Winter is calculated with the Region V HSPF2: 8.2 for the ARTCOOL PRESTIGE and 8.0 for the EXTRÊME R32. Summer, with the SEER2: 27.5 for the EXTRÊME R32 and 24.0 for the ARTCOOL PRESTIGE. The sliders show how the gap changes with hours of use.
Which one is quieter?
GREE publishes 35 to 49 dB(A) for the EXTRÊME R32; LG publishes 30 to 49 dB(A) in cooling for the ARTCOOL PRESTIGE, measured to ISO 3745. GREE does not publish its measurement conditions. These figures place each unit; they do not rank them.
Why are the pipes not the same?
LG calls for a 3/8 in liquid line and GREE for 1/4 in; both use a 5/8 in gas line. Each manufacturer sets the diameter of its circuit, and the installer follows it. If an existing line set is reused, its diameters must match the unit chosen.
GREE EXTRÊME and GREE AIRY 18,000 BTU: what is the difference?
The GREE AIRY R32 brochure carries the same model numbers as the 18,000 BTU EXTRÊME R32, and NEEP files certificate 215386340 under the “Airy” series. The indoor unit, remote, app and warranty can differ by name.
Are they eligible for rebates?
Eligibility depends on the official list in effect on the date of purchase. This page promises no amount; the current list is checked at quote time.
All AHRI and NEEP values
| Certified value | EXTRÊME R32 | ARTCOOL PRESTIGE R32 |
|---|---|---|
| Cooling | ||
| Rated capacity at 35 °C | 18,000 BTU/h | 18,000 BTU/h |
| Cooling capacity min. / max. at 35 °CBTU/h | 4,100 / 25,590 | 3,070 / 28,000 |
| SEER2 | 27.5 | 24.0 |
| EER2 | 14.3 | 14.4 |
| Heating, same conditions | ||
| HSPF2 Region IV / V | 10.0 / 8.0 | 11.0 / 8.2 |
| 8.3 °C: min. / rated / max.BTU/h | 5,000 / 18,600 / 23,000 | 3,070 / 21,600 / 27,400 |
| 8.3 °C: COP min. / rated / max. | 5.23 / 4.01 / 3.24 | 1.36 / 4.11 / 2.84 |
| −8.3 °C: min. / rated / max.BTU/h | 8,000 / 19,500 / 20,100 | 2,934 / 13,100 / 24,300 |
| −8.3 °C: COP min. / rated / max. | 2.61 / 1.90 / 1.90 | 1.34 / 2.91 / 2.08 |
| −15 °C: min. / rated / max.BTU/h | 6,800 / 18,000 / 18,000 | 2,730 / 21,600 / 21,600 |
| −15 °C: COP min. / rated / max. | 2.49 / 1.80 / 1.80 | 1.33 / 1.90 / 1.90 |
| Coldest point — different temperatures, not highlighted | ||
| Test temperature | −30 °C (−22 °F) | −25 °C (−13 °F) |
| Capacity min. / max. | 5,100 / 10,800 BTU/h | 2,218 / 14,780 BTU/h |
| COP at maximum capacity | 1.23 | 1.44 |
| Power at maximum capacity | 2.57 kW | 3.01 kW |
| Listings and refrigerant | ||
| ENERGY STAR / cold climate (NEEP) | Yes / Yes | Yes / Yes |
| AHRI certificate · NEEP record | 215386340 · 389441 | 215828275 · 385473 |
| RefrigerantGWP per the IPCC (AR4); ASHRAE 34 class | R-32 · GWP 675 · A2L | R-32 · GWP 675 · A2L |
higher marks the highest value for the same measurement, under the same conditions. It is not a recommendation. Capacities and COPs per point are not highlighted: the order changes depending on the value read (minimum, rated or maximum).
Both are on the AirGreen website.
To choose for your room, talk to our team: bring the room dimensions, the available wall width, the distance to the planned outdoor location and your current heating.
Where each figure comes from
Data checked November 9, 2026. Performance: AHRI certificates and the NEEP database. Dimensions, sound, piping and features: per the manufacturer. When a source contradicts the AHRI certificate, the certificate prevails.
Trademarks. GREE, EXTRÊME, LG, ARTCOOL and LGRED are trademarks of their respective owners. Logos are used only to identify the products compared. AirGreen is a dealer for both brands; this page is not produced, sponsored or endorsed by the manufacturers.
Photos: AirGreen and manufacturers, for identification.
Does a figure look wrong? Write to us : any data point reported is checked again.