The best dual-hose portable air conditioners

Portables are the least efficient way to cool a room and sometimes the only available one. If you are in that position, the hose count is the decision that matters most.

Every air conditioner needs two air streams: one passing over the cold evaporator to be cooled, and one passing over the hot condenser to carry heat away. A window unit gets these naturally — the indoor half faces in, the outdoor half faces out.

A portable sits entirely indoors, so both halves are in the room.

• Single hose: it draws room air across the condenser and blows it out of the window. The room is now short of that air, so it sucks replacement air in through every gap in the building — warm outdoor air, loft air, crawl space air. You are cooling one stream while importing another.
• Dual hose: one hose draws outdoor air in for the condenser, the other pushes it back out. The condenser loop is sealed off from the room, so indoor pressure stays neutral and no infiltration is created.

That is the whole difference, and it is structural rather than a matter of degree. A single-hose unit does not merely perform worse — it creates a problem the dual-hose unit does not have.

The effect is worst in a small room (infiltration is a larger share of the volume) and in a loft conversion (the make-up air comes from a roof void).

Portables carry two capacity numbers and only one of them is honest.

The box BTU is measured under ASHRAE-128 and ignores two real-world losses: heat radiating from the exhaust duct back into the room, and infiltration. DOE SACC — seasonally adjusted cooling capacity — subtracts both.

One thing worth stating plainly, because it is widely assumed and is not true: the size of the haircut is not predicted by hose count. Across the published pairs we hold, dual-hose models appear at both 14.3% and 32.1%. Two hoses is the right buy for the infiltration reason, not because it guarantees a smaller SACC gap. What SACC measures.

Window and through-the-wall units are covered by a certification program that publishes tested CEER and modeled annual kWh for every model. You can look any of them up and cost it exactly.

Portables are not in that program. There is no certified list, no tested efficiency figure, and no annual energy estimate for any portable air conditioner.

What that means in practice:

• Running cost has to be reconstructed from wattage, which some manufacturers publish and some do not. One of the two units here states none at all.
• No independent efficiency comparison exists between two portables. Any ranking — including ours — is working from capacity and manufacturer claims.
• Noise figures are uncertified dBA, measured however each brand chose.
• The ENERGY STAR logo you sometimes see on a portable listing is not for the air conditioner category, because that category does not exist here.

1. Insulate the exhaust hose. It runs hot, and every bit of that heat radiates back into the room it just left. This is the cheapest meaningful improvement available.
2. Keep the hose short and straight. Coiled hose is more surface area radiating indoors and more resistance to airflow.
3. Seal the window kit properly. The supplied panels are usually the weakest part of the installation, and gaps there undo the sealed loop you paid for.
4. Close the room. A portable sized for one room and asked to cool a floor will run continuously and never get there.
5. Measure the draw. A plug-in energy meter costs very little and settles what the machine actually uses — which for one of these is otherwise unknowable.
6. Reconsider a window unit annually. Circumstances change, and the running cost difference is large enough to be worth revisiting.