EcoFlow Wave 3

The EcoFlow Wave 3 is a small dual-duct portable that cools, heats and dehumidifies, and it can run from an optional clip-on battery. For home use, treat it as a premium answer for a box room, a compact home office or one of the garden rooms where a conventional portable is awkward to vent. Both ducts run outside, so it never draws warm air in from the rest of the house to replace what it blows out, and in sleep mode it drops to a quoted 44 dB, a gentle hum you can sleep beside. Its 6,100 BTU (1.8 kW) of cooling is modest, though, so it suits rooms of roughly 10 to 15 m² rather than a living room.

The catch is the money. At £799 for the unit alone it costs about twice as much as the MeacoCool Pro 9000, which gives you 9,000 BTU, and the add-on battery takes the bundle to £1,299. You also have two ducts to route and seal rather than one, a small condensate reservoir to empty or drain in humid weather, and a full-power setting of up to 58 dB that is too loud for a bedroom. If you can see a genuine use for the battery, in a garden room with no socket, through a power cut or on the odd camping trip, the premium starts to make sense; buy it purely for indoor cooling and a bigger conventional portable, or the Midea PortaSplit for a larger room, is better value. It is a well-made, versatile little unit that is hard to justify on cooling per pound alone.

EcoFlow made its name with portable power stations, and the Wave 3 is built around the same idea: an air conditioner you can run from the mains or from a battery. Unlike a standard single-hose portable, it has two insulated ducts, one drawing outside air in to cool its internal workings and one pushing the waste heat back out, so the room is not left pulling warm air in under the doors to make up the difference. Run the cycle the other way and it becomes a small heat pump, rated at 2,000 W of heat for about 645 W of electricity. Nothing needs fitting and no F-Gas engineer is involved; you set it down, run the ducts out through a window or a panel and plug it in.

Size it carefully. 1.8 kW of cooling is about two-thirds of what a typical 9,000 BTU portable offers, so it is happiest in a box room, a nursery, a small study or a well-insulated garden room of up to about 12 m². In a room of 15 m² or more, or a sunny loft, it takes the edge off rather than making the room cool, and that is where a bigger unit earns its keep; working out what size air conditioning you need before you buy saves a disappointing summer. It uses R290 refrigerant, which has a far lower climate impact than older types, and at 15.6 kg it is light enough to carry between rooms, though the battery adds another 9.7 kg.

It suits renters and anyone who cannot have a split system fitted, and it is a sensible option for rooms where a standard portable's wide hose and window kit are a poor fit. You still need a route outside for both ducts, though: three adapter covers and a cutting template come in the box for making a panel to suit a part-open window, and the first setup takes more planning than a single hose. Camping, campervans and off-grid cabins are where the battery comes into its own, but for most homes the mains-powered unit on its own does the job. As a niche product it has a shorter track record than the mainstream portables, and the 2-year warranty is standard rather than generous.

The Wave 3 lists at £799 for the unit alone and £1,299 with the 1,024 Wh add-on battery, so the battery is roughly a £500 extra. EcoFlow discounts it regularly, and the unit has dipped to around £699 in past sales, so it is worth waiting for a deal if you can. Stock is patchy in October 2026, with EcoFlow's own listing showing pre-order and some specialist sellers back-ordered into the new year, so check delivery dates as well as price. For context, a conventional 9,000 BTU portable costs around £400.

Running costs are low, because the unit is small. It is rated at 690 W on full cooling, which at the October 2026 Ofgem price cap of 26.32p per kWh works out at about 18p an hour, or roughly £1.45 for an eight-hour stint at full power. On eco or sleep mode, drawing around 250 to 300 W once the room is down to temperature, it is nearer 7p to 8p an hour. That is cheaper than most portables, but it also does less cooling, so the fair comparison is what it costs to keep your particular room comfortable.

Heating is the better value story. At about 645 W for 2,000 W of heat it costs around 17p an hour, against about 53p an hour for a 2 kW fan heater, which makes it a cheap way to take the chill off a small garden office in spring and autumn. Running from the battery costs a little more, since charging loses roughly a tenth of the energy, unless you top it up from solar panels or cheaper off-peak electricity. Prices correct as of October 2026; electricity rates updated for the October to December 2026 price cap. The energy price cap changes quarterly, so check current rates before budgeting.