LG H18S1D (18,000 BTU, 5 kW) - DUALCOOL Deluxe wall-mounted inverter air conditioner rated A+++

H18S1D: an 18 000 BTU machine rated A+++ in cooling

The H18S1D is the third capacity step of the DUALCOOL S1 Deluxe series: 5.0 kW of cooling, 5.8 kW of heating, 18 000 BTU and up to 50 m² on the card. The indoor unit differs from the smaller models of the series: 998 by 345 mm at a depth of 210 mm and weighing 13.5 kg, so wider and taller but slimmer than the 9 000 BTU unit with its 235 mm. The outdoor module has grown substantially - 870 by 650 by 330 mm and 38 kg - and this is the point where brackets and base are no longer chosen by eye. The series keeps class A+++ in cooling and A++ in heating even at this capacity, which is not common for an 18 000 BTU machine. Rated indoor noise is 23 dB(A), higher than the 19 dB(A) of the smaller models, but very quiet for a machine of this output.

5 kW for 50 m²: when the figure is real and when it is not

The 50 m² on the card assumes one thing: a regularly shaped space with one or two external walls and ceilings up to 2.7 m. In a long narrow room or a space broken up by partitions a wall unit physically cannot throw air to the far corner, and there 50 m² becomes 35 m² of comfort plus a stagnant zone. The throw of an 18 000 BTU unit reaches 9-11 metres along the ceiling, so the unit goes on the shorter wall, sending air down the length of the room rather than across it. For a kitchen-living space with a hob, an oven and a large window, 5 kW is a sensible minimum rather than a margin: appliances and sunlight easily add a couple of kilowatts of heat gain. If the space has several separate zones or a second level, the right answer is not a bigger wall unit but a CL18R cassette (item 1826) or a CT18R ducted unit (item 1836).

A 1/2 inch gas line and runs up to 25 metres

From this capacity upwards the installation changes: the liquid line stays at 1/4 inch while the gas line grows to 1/2 inch (12.7 mm), the maximum run becomes 25 m and the height difference 15 m. A 1/2 inch tube is stiffer and is not bent by hand: radii are formed with a bender, and in tight spots ready-made elbows are used. A long run buys freedom in placing the outdoor unit - on the roof of an extension, say, or on the far side of the house - but it requires topping up the R32 charge by weight at the specified rate per metre. Where the gas line rises more than 5-6 metres, oil traps are formed so that oil returns to the compressor; without them compressor life degrades invisibly and irreversibly. Insulation goes over each pipe separately rather than both in one sleeve: otherwise the liquid line warms the gas line and the machine loses capacity.

A 38 kg outdoor unit: base and access

Thirty-eight kilograms is a weight nobody lifts one-handed, and brackets for it are chosen with at least a twofold margin. The best arrangement in a detached house is a ground platform on vibration mounts, raised 30-40 cm above snow level, with 50 cm of free space in front of the grille and 15 cm behind. On the facade of an apartment block such a unit goes only into anchors in a load-bearing wall, never into insulation or hollow brick. The outdoor module is rated 60 dB(A), as across the whole series, so in dense housing its place is chosen away from windows rather than where the pipe run is shortest. Access for servicing is planned in advance too: the coil needs washing once a season, and that calls for a person with a washer reaching the unit, not just a ladder.

Electrics: what 18 000 BTU requires

The machine is single-phase, 220-240 V, 50 Hz, and at full cooling it draws roughly 1.5-1.7 kW, around 7-8 A of running current. It needs a dedicated circuit: 2.5 mm² copper with a breaker chosen to the design, and 4 mm² on long runs so that voltage is not lost in the cable. Class A+++ means that for most of the season the machine works between 20 and 50 per cent of capacity, so average consumption lands far below the peak. An inverter start produces no current surge, which matters in houses with a generator: an 18 000 BTU machine with direct starting would demand a generator with a large margin, while this one ramps up smoothly. Where mains voltage is unstable a protection relay is mandatory - the inverter board of a machine this size costs more than any relay in a junction box.

Control, maintenance and seasonal preparation

Control is by infrared remote and through LG ThinQ over Wi-Fi on the 2.4 GHz band, with scheduling, remote switching and consumption tracking in the app. Scheduling is especially useful for a 50 m² space: there is no point cooling a kitchen-living room or an office overnight, and in the morning the unit reaches temperature in 10-15 minutes. The coarse filters on a 998 mm unit have a large area and need rinsing every two or three weeks in season - at this capacity a clogged filter leads to icing quickly. Before the heating season it is worth checking drainage: in heating mode condensate forms on the outdoor unit, and if the water does not drain away, ice builds up beneath it. A full service clean of both coils once a year is no formality for this size: in a larger room the machine moves far more air, and far more dust with it.

Which jobs it fits and where it is out of place

The H18S1D belongs in a large living room, a kitchen-living space, an office for 8-12 desks, a small cafe or a shop with a regularly shaped sales floor, wherever the electricity bill matters. It also suits a detached house whose ground floor is one large volume opening onto a terrace: 5.8 kW of heating noticeably helps there in the shoulder seasons. Where the model is out of place: spaces of complex shape, several separate offices, halls with high ceilings - a wall unit creates a cold zone beside itself and stagnant air in the far corner. For those cases the catalogue has cassette, ducted and ceiling-floor units of the CL, CT and UV series, which distribute air evenly. And a server room or any space cooled year round needs a machine with a low-ambient kit, not a residential series.

How it differs from neighbouring models in this catalogue

The H12S1D (item 1801) is the 12 000 BTU machine of this series: 3.5 kW of cooling, up to 35 m², a 3/8 inch gas line and a 15 m run - a simpler and cheaper installation. The H24S1D (item 1803) is the 24 000 BTU version at 6.6 kW of cooling for 70 m², with a 5/8 inch line, runs up to 30 m and a 46 kg outdoor unit. The WZ18AWN (item 1806) is the simpler 18 000 BTU option in class A++ at 29 dB(A) instead of 23 dB(A), with an outdoor unit of the same 38 kg. The PC18SQ (item 1808) is the Standard Plus machine of the same 5.0 kW output with a 25 m run: simpler than Deluxe, rated A++ and with Wi-Fi. The S18EQ (item 1810) is the same as the PC18SQ without Wi-Fi, controlled only by the infrared remote: a rational choice where phone control is not needed.

Send us a floor plan with dimensions and mark where the outdoor unit could stand, and we will say whether one 5 kW wall unit is enough or a cassette is the better answer.